Note: Descriptions are shown in the official language in which they were submitted.
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RAIL ROAD CAR TRUCK AND BOLSTER THEREFOR
Field of the Invention
This invention relates to the field of rail road cars, and, more particularly,
to the field of
three piece rail road car trucks for rail road cars.
Background of the Invention
Rail road cars in North America commonly employ double axle swivelling trucks
known
as "three piece trucks" to permit them to roll along a set of rails. The three
piece terminology
refers to a truck bolster and pair of first and second sideframes. In a three
piece truck, the truck
bolster extends cross-wise relative to the sideframes, with the ends of the
truck bolster protruding
through the sideframe windows. Forces are transmitted between the truck
bolster and the
sideframes by spring groups mounted in spring seats in the sideframes. The
sideframes carry
forces to the sideframe pedestals. The pedestals seat on bearing adapters,
whence forces are
carried in turn into the bearings, the axle, the wheels, and finally into the
tracks. The 1980 Car &
Locomotive Cyclopedia states at page 669 that the three piece truck offers
"interchangeability,
structural reliability and low first cost but does so at the price of mediocre
ride quality and high
cost in terms of car and track maintenance."
Ride quality can be judged on a number of different criteria. There is
longitudinal ride
quality, where, often, the limiting condition is the maximum expected
longitudinal acceleration
experienced during humping or flat switching, or slack run-in and run-out.
There is vertical ride
quality, for which vertical force transmission through the suspension is the
key determinant.
There is lateral ride quality, which relates to the lateral response of the
suspension. There are also
other phenomena to be considered, such as truck hunting, the ability of the
truck to self steer, and,
whatever the input perturbation may be, the ability of the truck to damp out
undesirable motion.
These phenomena tend to be inter-related, and the optimization of a suspension
to deal with one
phenomenon may yield a system that may not necessarily provide optimal
performance in dealing
with other phenomena.
In terms of optimizing truck performance, it may be advantageous to be able to
obtain a
relatively soft dynamic response to lateral and vertical perturbations, to
obtain a measure of self
steering, and yet to maintain resistance to lozenging (or parallelogramming).
Lozenging, or
parallelogramming, is non-square deformation of the truck bolster relative to
the side frames of the
truck as seen from above. Self steering may tend to be desirable since it may
reduce drag and may
tend to reduce wear to both the wheels and the track, and may give a smoother
overall ride.
Among the types of truck discussed in this application are swing motion
trucks. An earlier
patent for a swing motion truck is US Patent 3,670,660 of Weber et al., issued
June 20, 1972. This
truck has unsprung lateral cross bracing, in the nature of a transom that
links the sideframes
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together. By contrast, the description that follows describes several
embodiments of truck that do
not employ lateral unsprung cross-members, but that may use damper elements
mounted in a four-
cornered arrangement at each end of the truck bolster. An earlier patent for
dampers is US Patent
3,714,905 of Barber, issued February 6, 1973.
Summary of the Invention
The present invention may provide a rail road car truck with bi-directional
rocking at the
sideframe pedestal to wheelset axle end interface. It may also provide a truck
that has self steering
that is proportional to the weight carried by the truck. It may further have a
longitudinal rocker at
the sideframe to axle end interface. Further it may provide a swing motion
truck with self
steering. It may also provide a swing motion truck that has the combination of
a swing motion
lateral rocker and an elastomeric bearing adapter pad.
In an aspect of the invention, there is a wheelset-to-sideframe interface
assembly for a
railroad car truck. The interface assembly has a bearing adapter and a mating
pedestal seat. The
bearing adapter has first and second ends that form an interlocking insertion
between a pair of
pedestal jaws of a railroad car sideframe. The bearing adapter has a first
rocking member. The
pedestal seat has a second rocking member. The first and second rocking
members are matingly
engageable to permit lateral and longitudinal rocking between them. There is a
resilient member
mounted between the bearing adapter and pedestal seat. The resilient member
has a portion
formed that engages the first end of the bearing adapter. The resilient member
has an
accommodation formed to permit the mating engagement of the first and second
rocking
members.
In a feature of that aspect of the invention, the resilient member has the
first and second
ends formed for interposition between the bearing adapter and the pedestal
jaws of the sideframe.
In another feature, the resilient member has the form of a Pennsy Pad with a
relief formed to
define the accommodation. In a further feature, the resilient member is an
elastomeric member.
In yet another feature, the elastomeric member is made of rubber material. In
still another feature,
the elastomeric member is made of a polyurethane material. In yet a further
feature, the
accommodation is formed through the elastomeric material and the first rocking
member protrudes
at least part way through the accommodation to meet the second rocking member.
In an
additional feature, the bearing adapter is a bearing adapter assembly which
includes a bearing
adapter body surmounted by the first rocker member. In another additional
feature, the first rocker
member is formed of a different material from the bearing body. In a further
additional feature,
the first rocker member is an insert.
In yet another additional feature, the first rocker member has a footprint
with a profile
conforming to the accommodation. In still another additional feature, the
profile and the
accommodation are mutually indexed to discourage mis-orientation of the first
rocker member
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relative to the bearing adapter. In yet a further additional feature, the body
and the first rocker
member are keyed to discourage mis-orientation between them. In a further
feature, the
accommodation is formed through the resilient member and the second rocking
member protrudes
at least part way through said accommodation to meet the first rocking member.
In another further
feature, the pedestal seat includes an insert with the second rocking member
formed in it. In yet
another further feature, the second rocker member has a footprint with a
profile conforming to the
accommodation.
In still a further feature, the portion of the resilient member that is formed
to engage the
first end of the bearing adapter, when installed, includes elements that are
interposed between the
first end of the bearing adapter and the pedestal jaw to inhibit lateral and
longitudinal movement
of the bearing adapter relative to the jaw.
In another aspect of the invention the ends of the bearing adapter includes an
end wall
bracketed by a pair of corner abutments. The end wall and corner abutments
define a channel to
permit the sliding insertion of the bearing adapter between the pedestal jaw
of the sideframe. The
portion of the resilient member that is formed to engage the first end of the
bearing adapter is the
first end portion. The resilient member has a second end portion that is
formed to engage the
second end of the bearing adapter. The resilient member has a middle portion
that extends
between the first and second end portions. The accommodation is formed in the
middle portion of
the resilient member. In another feature, the resilient member has the form of
a Pennsy Pad with a
central opening formed to define the accommodation.
In another aspect of the invention, a wheelset-to-sideframe interface assembly
for a rail
road car truck has an interface assembly that has a bearing adapter, a
pedestal seat and a resilient
member. The bearing adapter has a first end and a second end that each have a
end wall
bracketted by a pair of corner abutments. The end wall and corner abutments co-
operate to define
a channel that permits insertion of the bearing adapter between a pair of
thrust lugs of a sidewall
pedestal. The bearing adapter has a first rocking member. The pedestal seat
has a second rocking
member to make engagement with the first rocking member. The first and second
rocking
members, when engaged, are operable to rock longitudinally relative to the
sideframe to permit the
rail road car truck to steer. The resilient member has a first end portion
that is engageable with the
first end of the bearing adapter for interposition between the first end of
the bearing adapter and
the first pedestal jaw thrust lug. The resilient member has a second end
portion that is engageable
with the second end of the bearing adapter for interposition between the
second end of the bearing
adapter and the second pedestal jaw thrust lug. The resilient member has a
medial portion lying
between the first and second end portions. The medial portion is formed to
accommodate mating
rocking engagement of the first and second rocking members.
In another feature, there is a resilient pad that is used with the bearing
adapter which has a
,
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rocker member for mating and the rocking engagement with the rocker member of
the pedestal
seat. The resilient pad has a first portion for engaging the first end of the
bearing adapter, a
second portion for engaging a second end of the bearing adapter and a medial
portion between the
first and second end portions. The medial portion is formed to accommodate
mating engagement
of the rocker members.
In a feature of the aspect of the invention there is a wheelset-to-sideframe
assembly kit that
has a pedestal seat for mounting in the roof of a rail road car truck
sideframe pedestal. There is a
bearing adapter for mounting to a bearing of a wheelset of a rail road car
truck and a resilient
member for mounting to the bearing adapter. The bearing adapter has a first
rocker element for
engaging the seat in rocking relationship. The bearing adapter has a first end
and a second end,
both ends having an endwall and a pair of abutments bracketing the end wall to
define a channel,
that permits sliding insertion of the bearing adapter between a pair of
sideframe pedestal jaw
thrust lugs. The resilient member has a first portion that conforms to the
first end of the bearing
adapter for interpositioning between the bearing adapter and a thrust lug. The
resilient member
has a second portion connected to the first portion that, as installed, at
least partially overlies the
bearing adapter.
In another feature, the wheelset-to-sideframe assembly kit has a second
portion of the
resilient member with a margin that has a profile facing toward the first
rocker element. The first
rocker element is shaped to nest adjacent to the profile. In a further
feature, wheelset-to-sideframe
assembly kit has a bearing adapter that includes a body and the first rocker
element is separable
from that body. In still another feature, the wheelset-to-sideframe assembly
kit has a second
portion of the resilient member with a margin that has a profile facing toward
the first rocker
element which is shaped to nest adjacent the profile. In yet still another
feature, the wheelset-to-
sideframe assembly kit has a profile and first rocker element shaped to
discourage mis-orientation
of the first rocker element when installed. In another feature, the wheelset-
to-sideframe assembly
kit has a first rocker element with a body that is mutually keyed to
facilitate the location of the
first rocker element when installed. In still another feature, the wheelset-to-
sideframe assembly
kit has a first rocker element and body that are mutually keyed to discourage
mis-orientation of the
rocker element when installed. In yet still another feature, the wheelset-to-
sideframe assembly kit
has a first rocker element and a body with mutual engagement features. The
features are mutually
keyed to discourage mis-orientation of the rocker element when installed.
In a further feature, the kit has a second resilient member that conforms to
the second end
of the bearing adapter. In another feature, the wheelset-to-sideframe assembly
kit includes a
pedestal seat engagement fitting for locating the resilient feature relative
to the pedestal seat on the
assembly. In yet still another feature, the resilient member includes a second
end portion that
conforms to the second end of the bearing adapter.
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In an additional feature, there is a bearing adapter for transmitting load
between the
wheelset bearing and a sideframe pedestal of a railroad car truck. It has at
least a first and second
land for engaging the bearing and a relief formed between the first and second
land. The relief
extends predominantly axially relative to the bearing. In another additional
feature, the lands are
arranged in an array that conforms to the bearing and the relief is formed at
the apex of the array.
In still another additional feature, the bearing adapter includes a second
relief that extends
circumferencially relative to the bearing. In yet still another additional
feature, the axially
extending relief and the circumferentially extending relief extends along a
second axis of
symmetry of the bearing adapter.
In a further feature, the radially extending relief extends along a first axis
of symmetry of
the bearing adapter and the circumferentially extending relief extends along a
second axis of
symmetry of the bearing adapter. In still a further feature, the bearing
adapter has lands that are
formed on a circumferencial arc. In yet still another feature, the bearing
adapter has a rocker
element that has an upwardly facing rocker surface. In yet still a further
feature, the bearing
adapter has a body with a rocker element that is separable from the body.
In another aspect of the invention, there is a bearing adapter for
installation in a rail road car
truck sideframe pedestal. The bearing adapter has an upper portion engageable
with a pedestal seat,
and a lower portion engageable with a bearing casing. The lower portion has an
apex. The lower
portion includes a first land for engaging a first portion of the bearing
casing, and a second land
region for engaging a second portion of the bearing casing. The first land
lies to one side of the apex.
The second land lies to the other side of the apex. At least one relief
located between the first and
second lands.
In an additional feature, the relief has a major dimension oriented to extend
along the apex in
a direction that runs axially relative to the bearing when installed. In
another feature, the relief is
located at the apex. In another feature there are at least two the reliefs,
the two reliefs lying to either
side of a bridging member, the bridging member running between the first and
second lands.
In another aspect of the invention there is a kit for retro-fitting a railroad
car truck having
elastomeric members mounted over bearing adapters. The kit includes a mating
bearing adapter and
a pedestal seat pair. The bearing adapter and the pedestal seat have co-
operable bi-directional rocker
elements. The seat has a depth of section of greater than 1/2 inches.
In another aspect of the invention, there is a railroad car truck having a
bolster and a pair of
co-operating sideframes mounted on wheelsets for rolling operation along
railroad tracks. Truck has
rockers mounted between the sideframes to permit lateral swinging of the
sideframes. The truck is
free of lateral unsprung cross-bracing between the sideframes. The sideframes
each have a lateral
pendulum height, L, measured between a lower location at which gravity loads
are passed into the
sideframe, and an upper location at the rocker where a vertical reaction is
passed into the sideframes.
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The rocker includes a male element having a radius of curvature, r1, and a
ratio of ri: L is less than 3.
In a further feature of that aspect, the rocker has a female element in mating
engagement with
the male element. The female element has a radius of curvature R1 that is
greater than r1, and the
factor [ (1 / L) / ((1 / r1) ¨(1 / Ri))] is less than 3. In another further
feature, R1 is at least 4/3 as
large as r1, and r1 is greater than 15 inches.
In an aspect of the present invention, there is a rail road car truck that has
a self steering
capability and friction dampers in which the co-efficients of static and
dynamic friction are
substantially similar. It may include the added feature of lateral rocking at
the sideframe pedestal
to wheelset axle end interface. It may include self steering proportional to
the weight carried by
the truck. It may further have a longitudinal rocker at the sideframe to axle
end interface. Further
it may provide a swing motion truck with self steering. It may also provide a
swing motion truck
that has the combination of a swing motion lateral rocker and an elastomeric
bearing adapter pad.
In another feature, the truck may have dampers lying along the longitudinal
centerline of the
spring groups of the truck suspensions. In another feature, it may include
dampers mounted in a
four cornered arrangement. In another feature it may include dampers having
modified friction
surfaces on both the friction bearing face and on the obliquely angled face of
the damper that seats
in the bolster pocket.
In another aspect of the invention, a three piece rail road car truck has a
truck bolster mounted
transversely between a pair of sideframes. The truck bolster has ends, each of
the ends being
resiliently mounted to a respective one of the sideframes. The truck has a set
of dampers mounted in
a four cornered damper arrangement between each the bolster end and its
respective sideframe. Each
damper has a bearing surface mounted to work against a mating surface at a
friction interface in a
sliding relationship when the bolster moves relative to the sideframes. Each
damper has a seat
against which to mount a biasing device for urging the bearing face against
the mating surface. The
bearing surface of the damper has a dynamic co-efficient of friction and a
static co-efficient of
friction when working against the mating surface. The static and dynamic co-
efficients of friction are
of substantially similar magnitude.
In a further feature of that aspect of the invention, the co-efficients of
friction have respective
magnitudes within 10 % of each other. In another feature, the co-efficients of
friction are
substantially equal. In another feature the co-efficients of friction lie in
the range of 0.1 to 0.4. In
still another feature, the co-efficients of friction lie in the range 0.2 to
0.35. In a further feature, the
co-efficients of friction are about 0.30 (+/- 10 %). In still another feature,
the dampers each include a
friction element mounted thereto, and the bearing surface is a surface of the
friction element. In yet
still another feature, the friction element is a composite surface element
that includes a polymeric
material.
In another feature of that aspect of the invention, the truck is a self-
steering truck. In another
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feature, the truck includes a bearing adapter to sideframe pedestal interface
that includes a self-
steering apparatus. In another feature, the self-steering apparatus includes a
rocker. In a further
feature, the truck includes a bearing adapter to sideframe pedestal interface
that includes a self-
steering apparatus having a force-deflection characteristic varying as a
function of vertical load. In
still another feature, the truck has a bearing adapter to sideframe pedestal
interface that includes a bi-
directional rocker operable to permit lateral rocking of the sideframes and to
permit self-steering of
the truck.
In another feature of that aspect of the invention, each damper has an oblique
face for seating
in a damper pocket of a truck bolster of a rail road car truck, the bearing
face is a substantially vertical
face for bearing against a mating sideframe column wear surface, and, in use,
the seat is oriented to
face substantially downwardly. In another feature, the oblique face has a
surface treatment for
encouraging sliding of the oblique face relative to the damper pocket. In
still another feature, the
oblique face has a static coefficient of friction and a dynamic co-efficient
of friction, and the co-
efficients of static and dynamic friction of the oblique face are
substantially equal. In a further
feature, the oblique face and the bearing face both have sliding surface
elements, and both of the
sliding surface elements are made from materials having a polymeric component.
In yet a further
feature, the oblique face has a primary angle relative to the bearing surface,
and a cross-wise
secondary angle.
In another aspect of the invention, there is a three piece railroad car truck
having a bolster
transversely mounted between a pair of sideframes, and wheelsets mounted to
the sideframes at
wheelset to sideframe interface assemblies. The wheelset to sideframe
interface assemblies are
operable to permit self steering, and include apparatus operable to urge the
wheelsets in a lengthwise
direction relative to the sideframes to a minimum potential energy position
relative to the sideframes.
The self-steering apparatus has a force deflection characteristic that is a
function of vertical load.
In a further aspect of the invention, there is a bearing adapter for a
railroad car truck. The
bearing adapter has a body for seating upon a bearing of a rail road truck
wheelset, and a rocker
member for mounting to the body. The rocker member has a rocking surface, the
rocking surface
facing away from the body when the rocker member is mounted to the body, and
the rocker being
made of a different material from the body.
In a further feature of that aspect, the rocker member is made from a tool
steel. In another
feature of that aspect of the invention, the rocker member is made from a
metal of a grade used for
the fabrication of ball bearings. In another feature, the body is made of cast
iron. In another feature,
the rocker member is a bi-directional rocker member. In still another feature,
the rocking surface of
the rocking member defines a portion of a spherical surface.
In another aspect of the invention, there is a three piece railroad car truck
having rockers for
self steering. In still another aspect, there is a railroad car truck having a
sideframe, an axle bearing,
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and a rocker mounted between the sideframe and the axle bearing. The rocker
has a transverse axis to
permit rocking of and the bearing lengthwise relative to the sideframe.
In another aspect of the invention there is a three piece railroad car truck
having a bolster
mounted transversely to a pair of sideframes. The side frames have pedestal
fittings and wheelsets
mounted in the pedestal fittings. The pedestal fittings include rockers. Each
rocker has a transverse
axis to permit rocking in a lengthwise direction relative to the sideframes.
In another aspect of the invention there is a three piece railroad car truck
having a truck
bolster mounted transversely to a pair of side frames, each sideframes has
fore and aft pedestal seat
interface fittings, and a pair of wheelsets mounted to the pedestal seat
interface fittings. The pedestal
seat interface fittings include rockers operable to permit the truck to self
steer.
In another aspect of the invention there is a railroad car truck having a
sideframe, an axle
bearing, and a bi-directional rocker mounted between the sideframe and the
axle bearing. In still
another aspect of the invention, there is a railroad car truck having a truck
bolster mounted
transversely between a pair of sideframes, and wheelsets mounted to the
sideframes to permit rolling
operation of the truck along a set of rail road tracks. The truck includes
rocker elements mounted
between the sideframes and the wheelsets. The rocker elements are operable to
permit lateral
swinging of the sideframes and to permit self-steering of the truck.
In another aspect of the invention there is a railroad car truck having a pair
of sideframes, a
pair of wheelsets having ends for mounting to the sideframes, and sideframe to
wheelset interface
fittings. The sideframe to wheelset interface fittings include rocking members
having a first degree of
freedom permitting lateral swinging of the sideframes relative to the
wheelsets, and a second degree
of freedom permitting longitudinal rocking of the wheelset ends relative to
the sideframes.
In another aspect of the invention there is a railroad car truck having
rockers formed on a
compound curvature, the rockers being operable to permit both a lateral
swinging motion in the truck
and self steering of the truck. In still another aspect of the invention,
there is a railroad car truck
having a pair of sideframes, a pair of wheelsets having ends for mounting to
the sideframes, and
sideframe to wheelset interface fittings. The sideframe to wheelset interface
fittings include rocking
members having a first degree of freedom permitting lateral swinging of the
sideframes relative to the
wheelsets, a second degree of freedom permitting longitudinal rocking of the
wheelset ends relative
to the sideframes. The wheelset to sideframe interface fittings being
torsionally compliant about a
predominantly vertical axis.
In aspect of the invention there is a swing motion rail road car truck
modified to include
rocking elements mounted to permit self-steering. In yet another aspect there
is a swing motion rail
road car truck having a transverse bolster sprung between a pair of side
frames, and a pair of
wheelsets mounted to the sideframes at wheelset to sideframe interface
fittings. The wheelset to
sideframe interface fittings include swing motion rockers and elastomeric
members mounted in series
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with the swing motion rockers to permit the truck to self-steer.
In another aspect of the invention, there is a rail road car truck having a
truck bolster mounted
transversely between a pair of sideframes, and wheelsets mounted to the
sideframes at wheelset to
sideframe interface fittings. The wheelset to sideframe interface fittings
include rockers for
permitting lateral swinging motion of the sideframes. The rockers have a male
element and a mating
female element. The male and female rocker elements are engaged for co-
operative rocking
operation. The female element has a radius of curvature in the lateral
swinging direction of less than
25 inches. The wheelset to sideframe interface fittings are also operable to
permit self steering.
In still another aspect of the invention there is a rail road car truck having
a truck bolster
mounted transversely between a pair of sideframes, and wheelsets mounted to
the sideframes at
wheelset to sideframe interface fittings. The wheelset to sideframe interface
fittings include rockers
for permitting lateral swinging motion of the sideframes. The rockers have a
male element and a
mating female element. The male and female rocker elements are engaged for co-
operative rocking
operation. The sideframes have an equivalent pendulum length, Leg, when
mounted on the rocker, of
greater than 6 inches. The wheelset to sideframe interface fittings include an
elastomeric member
mounted in series with the rockers to permit self steering.
In yet another aspect of the invention there is a rail road car truck having a
truck bolster
mounted transversely between a pair of sideframes, and wheelsets mounted to
the sideframes at
wheelset to sideframe interface fittings. The wheelset to sideframe interface
fittings include rockers
for permitting self steering of the truck. The rockers have a male element and
a mating female
element. The male and female rocker elements are engaged for co-operative
rocking operation, and
the wheelset to sideframe interface fittings include an elastomeric member
mounted in series with the
rockers.
In still another aspect of the invention there is a rail road car truck having
a transverse bolster
sprung between two sideframes, and wheelsets mounted to the sideframes at
wheelset to sideframe
interface fittings, the truck having a spring groups and dampers seated in the
bolster and biased by the
spring groups to ride against the sideframes. The spring groups include a
first damper biasing spring
upon which a first damper of the dampers seats. The first damper biasing
spring has a coil diameter.
The first damper has a width of more than 150 % of the coil diameter.
In another aspect of the invention there is a rail road car truck having a
bolster having ends
sprung from a pair of sideframes, and wheelsets mounted to the sideframes at
wheelset to sideframe
interface fittings. The wheelset to sideframe interface fittings include bi-
directional rocker fittings for
permitting lateral swinging of the sideframes and for permitting self steering
of the wheelsets. The
truck has a four cornered arrangement of dampers mounted at each end of the
bolster. In a further
feature of that aspect of the invention the interface fittings are torsionally
compliant about a
predominantly vertical axis.
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In another aspect there is a railroad car truck having a bolster transversly
mounted between a
pair of sideframes, and wheelsets mounted to the sideframes. The rail road car
truck has a bi-
directional longitudinal and lateral rocking interface between each sideframe
and wheelset, and four
cornered damper groups mounted between each sideframe and the truck bolster.
In an additional
feature of that aspect of the invention the rocking interface is torsionally
compliant about a
predominantly vertical axis. In another additional feature, the rocking
interface is mounted in series
with a torsionally compliant member.
In yet another aspect of the invention there is a self-steering rail road car
truck having a
transversely mounted bolster sprung between two sideframes, and wheelsets
mounted to the
sideframes. The sideframes are mounted to swing laterally relative to the
wheelsets. The truck has
friction dampers mounted between the bolster and the sideframes. The friction
dampers have co-
efficients of static friction and dynamic friction. The co-efficients of
static and dynamic friction
being substantially the same.
In still another aspect there is a self-steering rail road car truck having a
transversely mounted
bolster sprung between two sideframes, and wheelsets mounted to the
sideframes. The sideframes
are mounted to swing laterally relative to the wheelsets. The truck has
friction dampers mounted
between the bolster and the sideframes. The friction dampers have co-
efficients of static friction and
dynamic friction. The co-efficients of static and dynamic friction differ by
less than 10 %. Expressed
differently, the friction dampers having a co-efficient of static friction, uõ
and a co-efficient of
dynamic friction, uk, and a ratio of us/uk lies in the range of 1.0 to 1.1. In
another aspect of the
invention, the truck has friction dampers mounted between the bolster and the
sideframes in a sliding
friction relationship that is substantially free of stick-slip behaviour. In
another feature of that aspect
of the invention the friction dampers include friction damper wedges having a
first face for engaging
one of the sideframes, and a second, sloped, face for engaging a bolster
pocket. The sloped face is
mounted in the bolster pocket in a sliding friction relationship that is
substantially free of stick-slip
behaviour.
In another aspect of the invention there is a self-steering rail road car
truck having a bolster
mounted between a pair of sideframes, and wheelsets mounted to the sideframes
for rolling motion
along railroad tracks. The wheelsets are mounted to the sideframes at wheelset
to sideframe interface
fittings. Those fittings are operable to permit lateral rocking of the
sideframes. The truck has a set of
friction dampers mounted between the bolster and each of the sideframes. The
friction dampers have
a first face in sliding friction relationship with the sideframes and a second
face seated in a bolster
pocket of the bolster. The first face, when operated in engagement with the
sideframe, has a co-
efficient of static friction and a co-efficient of dynamic friction, the co-
efficients of static and
dynamic friction of the first face differing by less than 10 %. The second
face, when mounted within
the bolster pocket, has a co-efficient of static friction, and a co-efficient
of dynamic friction, and the
CA 02488960 2004-12-03
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co-efficients of static and dynamic friction of the second face differing by
less than 10 %.
In yet another aspect of the invention there is a self-steering rail road car
truck having a
bolster mounted between a pair of sideframes, and wheelsets mounted to the
sideframes for rolling
motion along railroad tracks. The wheelsets are mounted to the sideframes at
wheelset to sideframe
interface fittings. The interface fittings are operable to permit lateral
rocking of the sideframes. The
truck has a set of friction dampers mounted between the bolster and each of
the sideframes. The
friction dampers have a first face in slidable friction relationship with the
sideframes and a second
face seated in a bolster pocket of the bolster. The first face and the side
frame are co-operable and are
in a substantially stick-slip free condition. The second face and the bolster
pocket are also in a
to substantially stick-slip free condition.
In another aspect of the invention there is a rocker for a bearing adapter of
a rail road car
truck. The rocker has a rocking surface for rocking engagement with a mating
surface of a pedestal
seat of a sideframe of a railroad car truck. The rocking surface has a
compound curvature to permit
both lengthwise and sideways rocking. In a complementary aspect of the
invention, there is a rocker
for a pedestal seat of a sideframe of a rail road car truck. The rocker has a
rocking surface for rocking
engagement with a mating surface of a bearing adapter of a railroad car truck.
The rocking surface
has a compound curvature to permit both lengthwise and sideways rocking.
In an aspect of the invention there is a sideframe pedestal to axle bearing
interface
assembly for a three piece rail road car truck, the interface assembly having
fittings operable to
rock both laterally and longitudinally.
In an additional feature of that aspect of the invention the assembly includes
mating
surfaces of compound curvature, the compound curvature including curvature in
both lateral and
horizontal directions. In another feature, the assembly includes at least one
rocker element and a
mating element, the rocker and mating elements being in point contact with a
mating element, the
element in point contact being movable in rolling point contact with the
mating element. In still
another feature, the element in point contact is movable in rolling point
contact with the mating
element both laterally and longitudinally. In yet another feature, the
fittings include rockingly
matable saddle surfaces.
In another feature, the fittings include a male surface having a first
compound curvature
and a mating female surface having a second compound curvature in rocking
engagement with
each other, and one of the surfaces includes at least a spherical portion. In
a further feature, the
fittings include a non-rocking central portion in at least one direction. In
still another feature,
relative to a vertical axis of rotation, rocking motion of the fittings
longitudinally is torsionally de-
coupled from rocking of the fittings laterally. In a yet further feature the
fittings include a force
transfer interface that is torsionally compliant relative to torsional moments
about a vertical axis.
In still another feature, the assembly includes an elastomeric member.
CA 02488960 2004-12-03
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In another aspect of the invention, there is a swing motion three piece rail
road car truck
having a laterally extending truck bolster, a pair of longitudinally extending
sideframes to which
the truck bolster is resiliently mounted, and wheelsets to which the side
frames are mounted.
Damper groups are mounted between the bolster and each of the sideframes. The
damper groups
each have a four-cornered damper layout, and wheelset to sideframe pedestal
interface assemblies
operable to permit lateral swinging motion of the sideframes and longitudinal
self-steering of the
wheelsets.
In a further aspect there is a rail road car truck having a truck bolster
mounted between
sideframes, and wheelsets to which the sideframes are mounted, and wheelset to
sideframe
interface assemblies by which to mount the sideframes to the wheelsets. The
sideframe to
wheelset interface assemblies include rocking apparatus to permit the
sideframes to swing
laterally. The rocking apparatus includes first and second surfaces in rocking
engagement. At
least a portion of the first surface has a first radius of curvature of less
than 30 inches. The
sideframe to wheelset interface includes self steering apparatus.
In a feature of that aspect of the invention, the self steering apparatus has
a substantially
linear force deflection characteristic. In another feature, the self steering
apparatus has a force-
deflection characteristic that varies with vertical loading of the sideframe
to wheelset interface
assembly. In a further feature, the force-deflection characteristic varies
linearly with vertical
loading of the sideframe to wheelset interface assembly. In another feature,
the self steering
apparatus includes a rocking element. In still another feature, the rocking
element includes a
rocking member subject to angular displacement about an axis transverse to one
of the sideframes.
In another feature, the self steering apparatus includes male and female
rocking elements,
and at least a portion of the male rocking element has a radius of curvature
of less than 45 inches.
In still another feature, the self steering apparatus includes male and female
rocking elements, and
at least a portion of the female rocking element has a radius of curvature of
less than 60 inches. In
still another feature the self steering apparatus is self centering. In a
further feature, the self
steering apparatus is biased toward a central position.
In yet another feature, the self steering apparatus includes a resilient
member. In a further
feature of that further feature, the resilient member includes an elastomeric
element. In another
further feature, the resilient member is an elastomeric adapter pad assembly.
In another feature,
the resilient member is an elastomeric adapter assembly having a lateral force-
displacement
characteristic and a longitudinal force-displacement characteristic, and the
longitudinal force-
displacement characteristic is different from the lateral force-displacement
characteristic. In
another feature, the elastomeric adapter assembly is stiffer in lateral shear
than in longitudinal
shear. In again another feature, a rocker element is mounted above the
elastomeric adapter pad
assembly. In another feature, a rocker element is mounted directly upon the
elastomeric adapter
_
_______________________________________________________________________________
___
CA 02488960 2004-12-03
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pad assembly. In a still further feature, the elastomeric adapter pad assembly
includes and integral
rocker member. In another feature, the three piece truck is a swing motion
truck and the self
steering apparatus includes an elastomeric bearing adapter pad.
In still another feature, the wheelsets have axles, and the axles have axes of
rotation, and
ends mounted beneath the sideframes, and, at one end of one of the axles, the
self steering
apparatus has a force deflection characteristic of at least one of the
characteristics chosen from the
set of force-deflection characteristic consisting of
(a) linear characteristic between 3000 lbs per inch and 10,000 pounds per
inch of
longitudinal deflection, measured at the axis of rotation at the end of the
axle when
the self steering apparatus bears one eighth of a vertical load of between
45,000
and 70,000 lbs.;
(b) linear characteristic between 16,000 lbs per inch and 60,000 pounds per
inch of
longitudinal deflection, measured at the axis of rotation at the end of the
axle when
the self steering apparatus bears one eighth of a vertical load of between
263,000
and 315,000 lbs.; and
(c) a linear characteristic between 0.3 and 2.0 lbs per inch of
longitudinal deflection,
measured at the axis of rotation at the end of the axle per pound of vertical
load
passed into the one end of the one axle.
In another aspect of the invention there is a three piece rail road freight
car truck having
self steering apparatus, wherein the passive steering apparatus includes at
least one longitudinal
rocker.
In an aspect of the invention, there is a three piece rail road freight car
truck having passive
self steering apparatus, the self steering apparatus having a linear force-
deflection characteristic,
and the force-deflection characteristic varying as a function of vertical
loading of the truck.
In an additional feature of that aspect of the invention, the force-
displacement
characteristic varies linearly with vertical loading of the truck. In another
feature, the self steering
apparatus includes a rocker mechanism. In another feature, the rocker
mechanism is displaceable
from a minimum energy state under drag force applied to a wheel of one of the
wheelsets. In still
another feature, the force-deflection characteristic lies in the range of
between about 0.4 lbs and
2.0 lbs per inch of deflection, measured at a center of and end of an axle of
a wheelset of the truck
per pound of vertical load passed into the end of the axle of the wheelset. In
a further feature, the
force deflection characteristic lies in the range of 0.5 to 1.8 lbs per inch
per pound of vertical load
passed into the end of the axle of the wheelset.
In yet another aspect of the invention there is a three piece rail road
freight car truck
having a transversely extending truck bolster, a pair of side frames mounted
at opposite ends of
the truck bolster, and resiliently connected thereto, and wheelsets. The
sideframes are mounted to
CA 02488960 2004-12-03
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the wheelsets at sideframe to wheelset interface assemblies. At least one of
the sideframe to
wheelset interface assemblies is mounted between a first end of an axle of one
of the wheelsets,
and a first pedestal of a first of the sideframes. The wheelset to sideframe
interface assembly
includes a first line contact rocker apparatus operable to permit lateral
swinging of the first
sideframe and a second line contact rocker apparatus operable to permit
longitudinal displacement
of the first end of the axle relative to the first sideframe.
In a feature of that aspect of the invention, the first and second rocker
apparatus are
mounted in series with a torsionally compliant member, the torsionally
complaint member being
compliant to torsional moments applied about a vertical axis. In another
feature, a torsionally
compliant member is mounted between the first and second rocker apparatus, the
torsionally
compliant member being torsionally compliant about a vertical axis.
In a further aspect of the invention, there is a bearing adapter for a three
piece rail road
freight car truck, the bearing adapter having a rocking contact surface for
rocking engagement
with a mating surface of a sideframe pedestal fitting, the rocking contact
surface of the bearing
adapter having a compound curvature.
In another feature of that aspect of the invention, the compound curvature is
formed on a
first male radius of curvature and a second male radius of curvature oriented
cross-wise thereto.
In another feature, the compound curvature is saddle shaped. In a further
feature, the compound
curvature is ellipsoidal. In a further feature, the curvature is spherical.
In a still further aspect there is a railroad car truck having a laterally
extending truck
bolster. The truck bolster has first and second ends. First and second
longitudinally extending
sideframes are resiliently mounted at the first and second ends of the bolster
respectively. The
side frames are mounted on wheelsets at sideframe to wheelset mounting
interface assemblies. A
four cornered damper group is mounted between each end of the truck bolster
and the respective
side frame to which that end is mounted. The sideframe to wheelset mounting
interface
assemblies are torsionally compliant about a vertical axis.
In a feature of that aspect of the invention, the truck is free of unsprung
lateral cross-
members between the sideframes. In another feature, the sideframes are mounted
to swing
laterally. In still another feature, the sideframe to wheelset mounting
interface assemblies include
self steering apparatus.
In another aspect of the invention, there is a railroad freight car truck
having wheelsets
mounted in a pair of sideframes, the sideframes having sideframe pedestals for
receiving the
wheelsets. The sideframe pedestals have sideframe pedestal jaws. The sideframe
pedestal jaws
include sideframe pedestal jaw thrust blocks. The wheelsets have bearing
adapters mounted thereto
for installation between the jaws. The sideframe pedestals have respective
pedestal seat members
rockingly co-operable with the bearing adapter. The truck has members mounted
intermediate the
CA 02488960 2004-12-03
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jaws and the bearing adapters for urging the bearing adapter to a centered
position relative to the
pedestal seat. In another aspect, there is a member for placement between the
thrust lug of a railroad
car sideframe pedestal jaw and the end wall and corner abutments of a bearing
adapter, the member
being operable to urge the bearing adapter to an at rest position relative to
the sideframe.
In another aspect of the invention there is a sideframe pedestal to axle
bearing interface
assembly for a three piece rail road car truck. The interface assembly has
fittings operable to rock
both laterally and longitudinally, and the interface assembly includes a
bearing assembly having
one of the rocking surface fittings defined integrally thereon.
In an additional feature of that aspect of the invention the bearing assembly
includes a
to
rocking surface of compound curvature. In another feature, the fittings
include rockingly matable
saddle surfaces. In yet another feature, the fittings include a male surface
having a first compound
curvature and a mating female surface having a second compound curvature in
rocking
engagement with each other. One of the surfaces includes a spherical portion.
In still another
feature, relative to a vertical axis of rotation, rocking motion of the
fittings longitudinally is
torsionally de-coupled from rocking of the fittings laterally. In still yet
another feature, the fittings
include a force transfer interface that is torsionally compliant relative to
torsional moments about a
vertical axis. In a further feature, the assembly includes a resilient biasing
member.
In an aspect of the invention there is a sideframe pedestal to axle bearing
interface
assembly for a three piece rail road car truck. The interface assembly has
fittings operable to rock
both laterally and longitudinally, and the interface assembly includes a
bearing assembly having
one of the rocking surface fittings defined integrally thereon.
In an additional feature of that aspect of the invention, the bearing assembly
includes a
rocking surface of compound curvature. In another feature, the fittings
include rockingly matable
saddle surfaces. In still another feature, the fittings include a male surface
having a first
compound curvature and a mating female surface having a second compound
curvature in rocking
engagement with each other, and one of the surfaces includes at least a
spherical portion. In yet
another feature, relative to a vertical axis of rotation, rocking motion of
the fittings longitudinally
is torsionally de-coupled from rocking of the fittings laterally. In still yet
another feature, the
fittings include a force transfer interface that is torsionally compliant
relative to torsional moments
about a vertical axis. In a further feature, the assembly includes a resilient
biasing member.
In another aspect of the invention, there is a sideframe pedestal to axle
bearing interface
assembly for a three piece rail road car truck. The interface assembly has
mating rocking surfaces.
The assembly includes a bearing mounted to an end of a wheelset axle. The
bearing has an outer
ring, and one of the rocking surfaces is rigidly fixed relative to the
bearing.
In still another aspect of the invention, there is a bearing for mounting to
one end of an
axle of a wheelset of a three-piece railroad car truck. The bearing has an
outer member mounted
CA 02488960 2004-12-03
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in a position to permit the end of the axle to rotate relative thereto, and
the outer member has a
rocking surface formed thereon for engaging a mating rolling contact surface
of a pedestal seat
member of a sideframe of the three piece truck. In an additional feature of
that aspect of the
invention, the bearing has an axis of rotation coincident with a centerline
axis of the axle and the
surface has a region of minimum radial distance from the center of rotation
and a positive
derivative dr/a between the region and points angularly adjacent thereto on
either side.
In another feature, the surface is cylindrical. In yet another feature, the
surface has a
constant radius of curvature. In still another feature, the cylinder has an
axis parallel to the axis of
rotation of the bearing. In still yet another feature, when installed in the
three piece truck, the
surface has a local minimum potential energy position, the position of minimum
potential energy
being located between positions of greater potential energy. In yet another
feature, the surface is a
surface of compound curvature. In still yet another feature, the surface has
the form of a saddle.
In a further feature, the surface has a radius of curvature. The bearing has
an axis of rotation, and
a region of minimum radial distance from the axis of rotation. The radius of
curvature is greater
than the minimum radial distance.
In yet a further feature, there is a combination of a bearing and a pedestal
seat. In an
additional feature, the bearing has an axis of rotation. A first location on
the surface of the bearing
lies radially closer to the axis of rotation than any other location thereon;
a first distance, L is
defined between the axis of rotation and the first location. The surface of
the bearing and the
surface of the pedestal seat each have a radius of curvature and mate in a
male and female
relationship. One radius of curvature is a male radius of curvature ri. The
other radius of
curvature is a female radius of curvature, R2; r1 being greater than L, R2 is
greater than ri, and L,
ri and R2 conform to the formula L-1 - (r1-1 - R2-1) > 0. In another
additional feature, the rocking
surfaces are co-operable to permit self steering.
In still another aspect of the invention there is a three-piece railroad
freight car truck. It
has a bolster sprung between sideframes. The bolster is mounted to permit
limited lateral travel
thereof relative to the sideframes. The bolster has a first range of lateral
travel relative to the
sideframes when loaded under a first magnitude of vertical load, and a second,
different, range of
lateral travel relative to the sideframes under a second, different magnitude
of vertical load.
In another feature, of that aspect of the invention, the second magnitude of
vertical load is
greater than the first magnitude, and the second range of lateral travel is
greater than the first
range. In a further feature, the bolster has the first range of travel in a
light car condition, and the
second range of travel in a fully laden car condition, the second range of
travel being greater than
the first range of travel. In yet another feature, the range of travel varies
as a function of vertical
loading of the bolster. In still another feature, the range of travel varies
linearly as a function of
vertical loading of the bolster. In a yet further feature, the range of travel
increases linearly as a
CA 02488960 2004-12-03
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function of increasing vertical load on the bolster. In another feature, the
first range permits
lateral motion to either side of an at rest position through a maximum
amplitude, and the
maximum amplitude is in the range of 3/8 to 3/4 of an inch. In another
feature, the second range
permits lateral motion to either side of an at rest position through a maximum
amplitude, and the
maximum amplitude is in the range of 7/8 to 1 3/8 inches. In a still further
feature, the bolster has a
first end resiliently mounted to a first of the sideframes and a second end
resiliently mounted to a
second of the sideframes, and dampers are mounted in four-cornered groups to
act between each
of the bolsters ends and the sideframes respectively. In another feature, the
dampers have non-
metallic friction surfaces. In another feature, the truck is self-steering. In
another feature, the
truck has sideframe to wheelset interface fittings permitting lateral swinging
motion thereof. In
yet another further feature, the truck has respective four cornered, non-stick-
slip groups of
dampers acting between the bolster and each of the sideframes, the truck has
sideframe to
wheelset interface fittings permitting lateral swinging motion thereof, and
the truck is a self-
steering truck. In another feature, the truck has dampers acting between the
bolster and each of
the sideframes, and one of the dampers has a damper body and a friction member
mounted to the
damper body, the friction member being operably mounted to bear against a co-
operating wear
plate during displacement of the bolster relative to one of the sideframes,
and the friction member
has a mounting permitting angular displacement of the friction member about at
least two axes of
rotation relative to the damper body while the friction member remains in
engagement with the
wear plate.
In still another aspect of the invention, there is a railroad freight car
truck having a bolster
sprung between sideframes, the bolster being mounted to permit lateral travel
thereof relative to
the sideframes, the bolster having a range of lateral travel whose magnitude
is a function of
vertical displacement of the bolster. In another feature of that aspect of the
invention, the range of
travel is a linear function of vertical displacement of the bolster. In still
another feature, the range
of lateral travel of the bolster increases with increasing downward vertical
displacement of the
bolster relative to the sideframes. In yet another feature, the range of
lateral travel of the bolster
is a linear function of downward displacement of the bolster, wherein the
range of lateral travel of
the bolster increases in a range of proportion of between 3/16 inches and 5/16
inches of additional
lateral travel for every 1 inch of additional downward deflection of the
bolster at rest.
In another aspect of the invention, there is a three piece rail road car
truck. It has
sideframes mounted to a pair of wheelsets, and a bolster extending cross-wise
between the
sideframes. The bolster has first and second ends each resiliently mounted to
a respective one of
the sideframes. The bolster has gibs. The sideframes have stops positioned to
oppose the gibs.
Mating pairs of respective ones of the gibs and the stops are co-operatively
engageable to limit
transverse displacement of the bolster relative to the sideframes. The bolster
has a first at rest
CA 02488960 2004-12-03
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position relative to the sideframes under a first vertical loading condition,
and a second at rest
position relative to the sideframes under a second, different, vertical
loading condition. In the first
at rest position of the bolster there being a first gap distance between a
first bolster gib and its
paired stop. In the second at rest position of the bolster there is a second,
different, gap distance
between that same first bolster gib and its paired stop.
In another feature of that aspect of the invention, the sideframes are mounted
to the
wheelsets at respective sideframe to wheelset interface fittings, and those
fittings include rocker
members permitting the sideframes to swing laterally. In another feature, the
truck has a four
cornered arrangement of dampers mounted to act between each of the sideframes
and a respective
one of the ends of the bolster. In another feature, the first bolster gib has
an abutment surface for
mating its paired stop, and the abutment surface is not confined to a vertical
plane. In another
feature, the bolster gib has an abutment surface for mating with its paired
stop, the abutment
surface being inclined with respect to vertical. In another feature, the
paired stop of the first
bolster gib has an abutment surface for engaging the first bolster gib, and
the abutment surface is
not confined to a vertical plane. In another feature, the paired stop of the
first bolster gib has an
abutment surface for engaging the first bolster gib, and the abutment surface
is inclined with
respect to vertical. In another feature, the first bolster gib and its paired
stop having mating
abutment surfaces for limiting lateral travel of the bolster, the mating
abutment surfaces being
inclined with respect to vertical. In another feature, the outboard bolster
gib is inclined with
respect to vertical. In another feature, both the inboard bolster gib and the
outboard bolster gib are
tapered with respect to vertical.
In still another aspect of the invention, there is a damper assembly for
installation between
a truck bolster and a sideframe of a three piece railroad car truck. The
damper assembly has a
damper body and a friction member mountable to the damper body, the damper
body is seatable
in a bolster pocket and is engageable by a damper biasing member. The friction
member having a
friction surface for engagement with a wear plate; and the friction member
having at least two
rotational degrees of freedom relative to the damper body when mounted
thereto.
In another feature of that aspect of the invention, the damper body and the
friction member
have mutually engaging arcuate surfaces, those surfaces being formed on a body
of revolution. In
another feature, the damper body and the friction member have mutually
engaging arcuate
surfaces, those surfaces being formed on a spherical arc. In another feature,
the mutually
engaging surfaced are in a non-rocking relationship. In another feature, the
surfaces are mounted
in a sliding relationship. In another feature, the body includes members for
engaging a biasing
member. In another feature, the body includes a sloped face for seating
against an inclined face of
a damper pocket, and the slope face is free of a crown. In another feature,
the friction member
includes a first portion for engagement with the damper body, and a second
portion for
CA 02488960 2004-12-03
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engagement with a wear plate, and the second portion is made from a different
material than the
first portion. In another feature, the surface of the friction member is
formed on a bulging portion
thereof, and the damper body includes a cavity for accommodating the bulging
portion of the
friction member. In another feature, the friction surface has a circular
footprint.
These and other aspects and features of the invention may be understood with
reference to
the detailed descriptions of the invention and the accompanying illustrations
as set forth below.
Brief Description of the Figures
The principles of the invention may better be understood with reference to the
accompanying figures provided by way of illustration of an exemplary
embodiment, or
113 embodiments, incorporating principles and aspects of the present
invention, and in which:
Figure la shows an isometric view of an example of an embodiment of a railroad
car
truck;
Figure lb shows a top view of the railroad car truck of Figure la;
Figure le shows a side view of the railroad car truck of Figure la;
Figure ld shows an exploded view of a portion of a truck similar to that of
Figure la;
Figure le is an exploded, sectioned view of an example of an alternate three
piece truck
to that of Figure la, having dampers mounted along the spring group
centerlines;
Figure if shows an isometric view of an example of an alternate railroad car
truck
according to that of Figure la;
Figure lg shows a side view of the railroad car truck of Figure if;
Figure lb shows a top view of the railroad car truck of Figure if;
Figure li is a split view showing, in one half an end view of the truck of
Figure if, and
in the other half and a section taken level with the truck center;
Figure lj shows a spring layout for the truck of Figure if;
Figure 2a is an enlarged detail of a side view of a truck such as the truck of
Figure la,
lb, lc or le taken at the sideframe pedestal to bearing adapter interface;
Figure 2b shows a lateral cross-section through the sideframe pedestal to
bearing adapter
interface of Figure 2a, taken at the wheelset axle centerline;
Figure 2c shows the cross-section of Figure 2b in a laterally deflected
condition;
Figure 2d is a longitudinal section of the pedestal seat to bearing adapter
interface of
Figure 2a, on the longitudinal plane of symmetry of the bearing adapter;
Figure 2e shows the longitudinal section of Figure 2d as longitudinally
deflected;
Figure 2f shows a top view of the detail of Figure 2a;
Figure 2g shows a staggered section of the bearing adapter of Figure 2a, on
section
lines '2g ¨ 2g' of Figure 2a;
Figure 3a shows an exploded isometric view of an alternate sideframe pedestal
to bearing
CA 02488960 2004-12-03
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adapter interface to that of Figure 2a;
Figure 3b shows an alternate bearing adapter to pedestal seat interface to
that of Figure
3a;
Figure 3c shows a sectional view of the assembly of Figure 3b; taken on a
longitudinal-
vertical plane of symmetry thereof;
Figure 3d shows a stepped sectional view of a detail of the assembly of Figure
3b taken
on 3d ¨ 3d' of Figure 3c;
Figure 3e shows an exploded view of another alternative embodiment of bearing
adapter
to pedestal seat interface to that of Figure 3a;
Figure 4a shows an isometric view of a retainer pad of the assembly of Figure
3a, taken
from above, and in front of one corner;
Figure 4b is an isometric view from above and behind the retainer pad of
Figure 4a;
Figure 4c is a bottom view of the retainer pad of Figure 4a;
Figure 4d is a front view of the retainer pad of Figure 4a;
Figure 4e is a section on '4e ¨ 4e' of Figure 4d of the retainer pad of Figure
4a;
Figure 5 shows an alternate bolster, similar to that of Figure id, with a pair
of spaced
apart bolster pockets, and inserts with primary and secondary wedge angles;
Figure 6a is a cross-section of an alternate damper such as may be used, for
example, in
the bolster of the trucks of Figures la, lb, lc, id and if;
Figure 6b shows the damper of Figure 6a with friction modifying pads removed;
Figure 6c is a reverse view of a friction modifying pad of the damper of
Figure 6a;
Figure 7a is a front view of a friction damper for a truck such as that of
Figure la;
Figure 7b shows a side view of the damper of Figure 7a;
Figure 7c shows a rear view of the damper of Figure 7b;
Figure 7d shows a top view of the damper of Figure 7a;
Figure 7e shows a cross-sectional view on the centerline of the damper of
Figure 7a taken
on section '7e ¨ 7e' of Figure 7c;
Figure 7f is a cross-section of the damper of Figure 7a taken on section '7f¨
71' of Figure
7e;
Figure 7g shows an isometric view of an alternate damper to that of Figure 7a
having a
friction modifying side face pad;
Figure 7h shows an isometric view of a further alternate damper to that of
Figure 7a,
having a "wrap-around" friction modifying pad;
Figure 8a shows an exploded isometric installation view of an alternate
bearing adapter
assembly to that of Figure 3a;
Figure 8b shows an isometric, assembled view of the bearing adapter assembly
of Figure
CA 02488960 2004-12-03
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8a;
Figure 8c shows the assembly of Figure 8b with a rocker member thereof
removed;
Figure 8d shows the assembly of Figure 8b, as installed, in longitudinal cross-
section;
Figure 8e is an installed view of the assembly of Figure 8b, on section '8e ¨
8e' of Figure
8d;
Figure 8f shows the assembly of Figure 8b, as installed, in lateral cross
section;
Figure 9a shows an exploded isometric view of an alternate assembly to that of
Figure 3a;
Figure 9b shows an exploded isometric view similar to the view of Figure 9a,
showing a
bearing adapter assembly incorporating an elastomeric pad;
Figure 10a shows an exploded isometric view of an alternate assembly to that
of Figure
3a;
Figure 10b shows a perspective view of a bearing adapter of the assembly of
Figure 10a
from above and to one corner;
Figure 10c shows a perspective of the bearing adapter of Figure 10b from
below;
Figure 10d shows a bottom view of the bearing adapter of Figure 10b;
Figure 10e shows a longitudinal section of the bearing adapter of Figure 10b
taken on
section '10e ¨ 10e' of Figure 10d; and
Figure 10f shows a transverse section of the bearing adapter of Figure 10b
taken on section
'10f¨ 101÷ of Figure 10d;
Figure lla is an exploded view of an alternate bearing adapter assembly to
that of Figure
3a;
Figure lib shows a view of the bearing adapter of Figure ha from below and to
one
corner;
Figure 11c is a top view of the bearing adapter of Figure 11b;
Figure lid is a lengthwise section of the bearing adapter of Figure 11c on
'lid ¨ lid';
Figure lie is a cross-wise section of the bearing adapter of Figure 11c on
'lie¨ lie'; and
Figure llf is a set of views of a resilient pad member of the assembly of
Figure 11a;
Figure hg shows a view of the bearing adapter of Figure ha from above and to
one
corner;
Figure 12a shows an exploded isometric view of an alternate bearing adapter to
pedestal
seat assembly to that of Figure 3a;
Figure 12b shows a longitudinal central section of the assembly of Figure 12a,
as
assembled;
Figure 12c shows a section on '12c ¨ 12c' of Figure 12b; and
Figure 12d shows a section on '12d ¨ 12d' of Figure 12b;
Figure 13a shows a top view of an embodiment of bearing adapter and pedestal
seat
CA 02488960 2004-12-03
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such as could be used in a side frame pedestal similar to that of Figure 2a,
with
the seat inverted to reveal a female depression formed therein for engagement
with the bearing adapter;
Figure 13b shows a side view of the bearing adapter and seat of Figure 13a;
Figure 13c shows a longitudinal section of the bearing adapter of Figure 13a
taken on
section '13c ¨ 13c' of Figure 13d;
Figure 13d shows an end view of the bearing adapter and pedestal seat of
Figure 13a;
Figure 13e shows a transverse section of the bearing adapter of Figure 13a,
taken on
the wheelset axle centreline;
Figure 13f is a section in the transverse plane of symmetry of a bearing
adapter and
pedestal seat pair like that of Figure 13e, with inverted rocker and seat
portions;
Figure 13g shows a cross-section on the longitudinal plane of symmetry of the
bearing
adapter and pedestal seat pair of Figure 13f;
Figure 14a shows an isometric view of an alternate embodiment of bearing
adapter and
pedestal seat to that of Figure 13a having a fully curved upper surface;
Figure 14b shows a side view of the bearing adapter and seat of Figure 14a;
Figure 14c shows an end view of the bearing adapter and seat of Figure 14a;
Figure 14d shows a cross-section of the bearing adapter and pedestal seat of
Figure 14a
taken on the longitudinal plane of symmetry;
Figure 14e shows a cross-section of the bearing adapter and pedestal seat of
Figure 14a
taken on the transverse plane of symmetry;
Figure 15a shows a top view of an alternate bearing adapter and an inverted
view of an
alternate female pedestal seat to that of Figure 13a;
Figure 15b shows a longitudinal section of the bearing adapter of Figure 15a;
Figure 15c shows an end view of the bearing adapter and seat of Figure 15a;
Figure 16a shows an isometric view of a further embodiment of bearing adapter
and
seat combination to that of Figure 13a, in which the bearing adapter and
pedNal
seat have saddle shaped engagement interfaces;
Figure 16b shows an end view of the bearing adapter and pedestal seat of
Figure 16a;
Figure 16c shows a side view of the bearing adapter and pedestal seat of
Figure 16a;
Figure 16d is a lateral section of the adapter and pedestal seat of Figure
16a;
Figure 16e is a longitudinal section of the adapter and pedestal seat of
Figure 16a;
Figure 16f shows a transverse cross section of a bearing adapter and pedestal
seat pair
having an inverted interface to that of Figure 16a;
Figure 16g shows a longitudinal cross section for the bearing adapter and
pedestal seat
pair of Figure 16f;
_ _
CA 02488960 2004-12-03
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Figure 17a shows an exploded side view of a further alternate bearing adapter
and seat
combination to that of Figure 13a, having a pair of cylindrical rocker
elements,
and a pivoted connection therebetween;
Figure 17b shows an exploded end view of the bearing adapter and seat of
Figure 17a;
Figure 17c shows a cross-section of the bearing adapter and seat of Figure
17a, as
assembled, taken on the longitudinal centreline thereof;
Figure 17d shows a cross-section of the bearing adapter and seat of Figure
17a, as
assembled, taken on the transverse centreline thereof;
Figure 17e shows possible permutations of the assembly of Figure 17a;
Figure 18a is an exploded end view of an alternate version of bearing adapter
and seat
assembly to that of Figure 17a having an elastomeric intermediate member;
Figure 18b shows an exploded side view of the assembly of Figure 18a;
Figure 19a is a side view of alternate assembly to that of Figure 13a or 16a,
employing
an elastomeric shear pad and a laterally swinging rocker;
Figure 19b shows a transverse cross-section of the assembly of Figure 19a,
taken on
the axle center line thereof;
Figure 19c shows a cross section of the assembly of Figure 19a taken on the
longitudinal plane of symmetry of the bearing adapter;
Figure 19d shows a sectional view of the alternate assembly of Figure 19a, as
viewed
from above, taken on the staggered section indicated as `19d ¨ 19d';
Figure 19e shows an end view of an alternate rocker combination to that of
Figure 19a
employing an elastomeric pad;
Figure 19f shows a perspective view of the alternate pad combination of Figure
19e;
Figure 20a is a view of a bearing adapter for use in the assembly of Figure
19a;
Figure 20b shows a top view of the bearing adapter of Figure 20a;
Figure 20c shows a longitudinal cross-section of the bearing adapter of Figure
20a;
Figure 21a shows an isometric view of a pad adapter for the assembly of Figure
19a;
Figure 21b shows a top view of the pad adapter of Figure 21a;
Figure 21c shows a side view of the pad adapter of Figure 21a;
Figure 21d shows a half cross-section of the pad adapter of Figure 21a;
Figure 21e shows an isometric view of a rocker for the pad adapter of Figure
21a;
Figure 21f shows a top view of the rocker of Figure 21a;
Figure 21g shows an end view of the rocker of Figure 21a;
Figure 22a shows an end view of an alternate arrangement of wheelset to
pedestal irtfaze
assembly arrangement to that of Figure 2a, having mating bi- directionally
arcuate rocking
members, one being formed integrally as an outer portion of a bearing;
CA 02488960 2011-08-22
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Figure 22b shows a cross-section of the assembly of Figure 22a taken on '22b -
22b' of Figure
= 22a;
Figure 22c shows a cross-section of the assembly of Figure 22a as viewed in
the direction of
arrows '22c - 22c' of Figure 22b;
Figure 23a shows an end view of an alternate assembly to that of Figure 22a
incorporating a uni-
directionally fore-and-aft rocking member;
Figure 23b shows a cross-sectional view taken on '23b - 23b' of Figure 23a;
Figure 24a shows an isometric view of an alternate three piece truck to that
of Figure la;
Figure 24b shows a side view of the three piece truck of Figure 24a;
Figure 24c shows a top view of half of the three piece truck of Figure 24b;
Figure 24d shows a partial section of the truck of Figure 24b taken on '24d -
24d';
Figure 24e shows a partial isometric view of the truck bolster of the three
piece truck of Figure
24a showing friction damper seats;
Figure 24f shows a force schematic for four cornered damper arrangements
generally, such as,
for example, in the trucks of Figures la, if, and Figure 24a;
Figure 25a shows a side view of an alternate three piece truck to that of
Figure 24a;
Figure 25b shows a top view of half of the three piece truck of Figure 25a;
and
Figure 25c shows a partial section of the truck of Figure 25a taken on '25c -
25c';
Figure 25d shows an exploded isometric view of the bolster and side frame
assembly of Figure
25a, in which horizontally acting springs drive constant force dampers;
Figure 26a shows an alternate version of the bolster of Figure 24e, with a
double sized damper
pocket for seating a large single wedge having a welded insert;
Figure 26b shows an alternate dual wedge for a truck bolster like that of
Figure 26a;
Figure 27a shows an alternate bolster arrangement similar to that of Figure 5,
but having split
wedges;
Figure 27b shows a bolster similar to that of Figure 24a, having a wedge
pocket having primary
and secondary angles and a split wedge arrangement for use therewith;
Figure 27c shows an alternate stepped single wedge for the bolster of Figure
27b;
Figure 28a shows an alternate bolster and wedge arrangement to that of Figure
17b, having
secondary wedge angles;
Figure 28b shows an alternate, split wedge arrangement for the bolster of
Figure 28a;
Figure 29a shows a 3 dimensional view of a section through a sideframe of an
embodiment of a
truck such as shown in Figure la, if, or li showing a tapered gib arrangement;
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Figure 29b shows an orthogonal view of the gib arrangement of Figure 29a
looking pada
to the long axis of the sideframe in a light c-condition;
Figure 29c shows the gib arrangement of Figure 29b in a laded condition;
Figure 29d shows a top view of the gib arrangement of Figure 29a;
Figure 29e shows an alternate gib arrangement to that of Figure 29b, having
tapered inboard
and outboard gibs;
Figure 29f shows another alternate gib arrangement to that of Figure 29b;
Figure 30a shows an exploded three-dimensional view of an alternate damper
assembly such
as may be used in the truck of Figure la, or other trucks herein;
Figure 30b shows an isometric view of the damper assembly of Figure 30a from
in front,
above, and to one corner;
Figure 30c shows an opposite isometric view of the damper assembly of Figure
30b;
Figure 30d shows a front view of the damper assembly of Figure 30a;
Figure 30e shows a rear view of the damper assembly of Figure 30a;
Figure 30f shows a bottom view of the samper assembly of Figure 30a; and
Figure 30g shows a mid-sectional view on a vertical plane '30g ¨ 30g' of the
damper
assembly of Figure 30e.
Detailed Description of the Invention
The description that follows, and the embodiments described therein, are
provided by way
of illustration of an example, or examples, of particular embodiments of the
principles of aspects
of the present invention. These examples are provided for the purposes of
explanation, and not of
limitation, of those principles and of the invention. In the description, like
parts are marked
throughout the specification and the drawings with the same respective
reference numerals. The
drawings are not necessarily to scale and in some instances proportions may
have been
exaggerated in order more clearly to depict certain features of the invention.
In terms of general orientation and directional nomenclature, for each of the
rail road car
trucks described herein, the longitudinal direction is defined as being
coincident with the rolling
direction of the rail road car, or rail road car unit, when located on tangent
(that is, straight) track.
In the case of a rail road car having a center sill, the longitudinal
direction is parallel to the center
sill, and parallel to the side sills, if any. Unless otherwise noted,
vertical, or upward and
downward, are terms that use top of rail, TOR, as a datum. The term lateral,
or laterally outboard,
refers to a distance or orientation relative to the longitudinal centerline of
the railroad car, or car
unit. The term "longitudinally inboard", or "longitudinally outboard" is a
distance taken relative
to a mid-span lateral section of the car, or car unit. Pitching motion is
angular motion of a railcar
unit about a horizontal axis perpendicular to the longitudinal direction.
Yawing is angular motion
CA 02488960 2012-08-29
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about a vertical axis. Roll is angular motion about the longitudinal axis.
This description relates to rail car trucks and truck components. Several AAR
standard
truck sizes are listed at page 711 in the 1997 Car & Locomotive Cyclopedia. As
indicated, for a
single unit rail car having two trucks, a "40 Ton" truck rating corresponds to
a maximum gross car
weight on rail (GRL) of 142,000 lbs. Similarly, "50 Ton" corresponds to
177,000 lbs., "70 Ton"
corresponds to 220,000 lbs., "100 Ton" corresponds to 263,000 lbs., and "125
Ton" corresponds
to 315,000 lbs. In each case the load limit per truck is then half the maximum
gross car weight on
rail. Two other types of truck are the "110 Ton" truck for railcars having a
286,000 lbs. GRL and
the "70 Ton Special" low profile truck sometimes used for auto rack cars.
Given that the rail road
car trucks described herein tend to have both longitudinal and transverse axes
of symmetry, a
description of one half of an assembly may generally also be intended to
describe the other half as
well, allowing for differences between right hand and left hand parts.
This description refers to friction dampers for rail road car trucks, and
multiple
friction damper systems. There are several types of damper arrangements, some
being shown at
pp. 715-716 of the 1997 Car and Locomotive Cyclopedia. Each of the
arrangements of
dampers shown at pp. 715 to 716 of the 1997 Car and Locomotive Cyclopedia can
be modified
to employ a four cornered, double damper arrangement of inner and outer
dampers.
In terms of general nomenclature, damper wedges tend to be mounted within an
angled
"bolster pocket" formed in an end of the truck bolster. In cross-section, each
wedge may then
have a generally triangular shape, one side of the triangle being, or having,
a bearing face, a
second side which might be termed the bottom, or base, forming a spring seat,
and the third side
being a sloped side or hypotenuse between the other two sides. The first side
may tend to have a
substantially planar bearing face for vertical sliding engagement against an
opposed bearing face
of one ofthe sideframe columns. The second face may not be a face, as such,
but rather may have
the form of a socket for receiving the upper end of one of the springs of a
spring group. Although
the third face, or hypotenuse, may appear to be generally planar, it may tend
to have a slight
crown, having a radius of curvature of perhaps 60". The crown may extend along
the slope and
may also extend across the slope. The end faces of the wedges may be generally
flat, and may
have a coating, surface treatment, shim, or low friction pad to give a smooth
sliding engagement
with the sides of the bolster pocket, or with the adjacent side of another
independently slidable
damper wedge, as may be.
During railcar operation, the sideframe may tend to rotate, or pivot, through
a small range
of angular deflection about the end of the truck bolster to yield wheel load
equalisation. The slight
crown on the slope face of the damper may tend to accommodate this pivoting
motion by allowing
the damper to rock somewhat relative to the generally inclined face of the
bolster pocket while the
CA 02488960 2004-12-03
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planar bearing face remains in planar contact with the wear plate of the
sideframe column.
Although the slope face may have a slight crown, for the purposes of this
description it will be
described as the slope face or as the hypotenuse, and will be considered to be
a substantially flat
face as a general approximation.
In the terminology herein, wedges have a primary angle a, being the included
angle
between (a) the sloped damper pocket face mounted to the truck bolster, and
(b) the side frame
column face, as seen looking from the end of the bolster toward the truck
center. In some
embodiments, a secondary angle may be defined in the plane of angle a, namely
a plane
perpendicular to the vertical longitudinal plane of the (undeflected) side
frame, tilted from the
vertical at the primary angle. That is, this plane is parallel to the
(undeflected) long axis of the
truck bolster, and taken as if sighting along the back side (hypotenuse) of
the damper. The
secondary angle p is defined as the lateral rake angle seen when looking at
the damper parallel to
the plane of angle a. As the suspension works in response to track
perturbations, the wedge forces
acting on the secondary angle p may tend to urge the damper either inboard or
outboard according
to the angle chosen.
General Description of Truck Features
Figures la and if provide examples of trucks 20 and 22 may have the same, or
generally
similar, features and similar construction, although they may differ in
pendulum length, spring
stiffness, wheelbase, window width and height, and damping arrangement. That
is, truck 20 of
Figure if may tend to have a longer wheelbase (from 73 inches to 86 inches,
possibly between 80
¨ 84 inches for truck 20, as opposed to a wheelbase of 63 ¨ 73 inches for
truck 22), may tend to
have a main spring group having a softer vertical spring rate, and a four
cornered damper group
that may have different primary and secondary angles on the damper wedges.
Truck 20 may have
a 5 x 3 spring group arrangement, while truck 22 may have a 3 x3 arrangement.
While either
truck may be suitable for a variety of general purpose uses, truck 20 may be
optimized for
carrying relatively low density, high value lading, such as automobiles or
consumer products, for
example, whereas truck 22 may be optimized for carrying denser semi-finished
industrial goods,
such as might be carried in rail road freight cars for transporting rolls of
paper. The various
features of the two truck types may be interchanged, and are intended to be
illustrative of a wide
range of truck types. Notwithstanding possible differences in size, generally
similar features are
given the same part numbers. Trucks 20 and 22 are symmetrical about both their
longitudinal and
transverse, or lateral, centreline axes. In each case, where reference is made
to a sideframe, it will
be understood that the truck has first and second sideframes, first and second
spring groups, and so
on.
Trucks 20 and 22 each have a truck bolster 24 and sideframes 26. Each
sideframe 26 has a
generally rectangular window 28 that accommodates one of the ends 30 of the
bolster 24. The
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upper boundary of window 28 is defined by the sideframe arch, or compression
member identified
as top chord member 32, and the bottom of window 28 is defined by a tension
member identified
as bottom chord 34. The fore and aft vertical sides of window 28 are defined
by sideframe
columns 36. The ends of the tension member sweep up to meet the compression
member. At
each of the swept-up ends of sideframe 26 there are sideframe pedestal
fittings, or pedestal seats
38. Each fitting 38 accommodates an upper fitting, which may be a rocker or a
seat, as described
and discussed below. This upper fitting, whichever it may be, is indicated
generically as 40.
Fitting 40 engages a mating fitting 42 of the upper surface of a bearing
adapter 44. Bearing
adapter 44 engages a bearing 46 mounted on one of the ends of one of the axles
48 of the truck
adjacent one of the wheels 50. A fitting 40 is located in each of the fore and
aft pedestal fittings
38, the fittings 40 being longitudinally aligned so the sideframe can swing
sideways relative to the
truck's rolling direction.
The relationship of the mating fittings 40 and 42 is described at greater
length below. The
relationship of these fittings determines part of the overall relationship
between an end of one of
the axles of one of the wheelsets and the sideframe pedestal. That is, in
determining the overall
response, the degrees of freedom of the mounting of the axle end in the
sideframe pedestal involve
a dynamic interface across an assembly of parts, such as may be termed a
wheelset to sideframe
interface assembly, that may include the bearing, the bearing adapter, an
elastomeric pad, if used,
a rocker if used, and the pedestal seat mounted in the roof of the sideframe
pedestal. Several
different embodiments of this wheelset to sideframe interface assembly are
described below. To
the extent that bearing 46 has a single degree of freedom, namely rotation
about the wheelshaft
axis, analysis of the assembly can be focused on the bearing to pedestal seat
interface assembly, or
on the bearing adapter to pedestal seat interface assembly. For the purposes
of this description,
items 40 and 42 are intended generically to represent the combination of
features of a bearing
adapter and pedestal seat assembly defining the interface between the roof of
the sideframe
pedestal and the bearing adapter, and the six degrees of freedom of motion at
that interface,
namely vertical, longitudinal and transverse translation (i.e., translation in
the z, x, and y
directions) and pitching, rolling, and yawing (i.e., rotational motion about
the y, x, and z axes
respectively) in response to dynamic inputs.
The bottom chord or tension member of sideframe 26 may have a basket plate, or
lower
spring seat 52 rigidly mounted thereto. Although trucks 20 and 22 may be free
of unsprung lateral
cross-bracing, whether in the nature of a transom or lateral rods, in the
event that truck 20 or 22 is
taken to represent a "swing motion" truck with a transom or other cross
bracing, the lower rocker
platform of spring seat 52 may be mounted on a rocker, to permit lateral
rocking relative to
sideframe 26. Spring seat 52 may have retainers for engaging the springs 54 of
a spring set, or
spring group, 56, whether internal bosses, or a peripheral lip for
discouraging the escape of the
CA 02488960 2004-12-03
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bottom ends of the springs. The spring group, or spring set 56, is captured
between the distal end
30 of bolster 24 and spring seat 52, being placed under compression by the
weight of the rail car
body and lading that bears upon bolster 24 from above.
Bolster 24 has double, inboard and outboard, bolster pockets 60, 62 on each
face of the
bolster at the outboard end (i.e., for a total of 8 bolster pockets per
bolster, 4 at each end). Bolster
pockets 60, 62 accommodate fore and aft pairs of first and second, laterally
inboard and laterally
outboard friction damper wedges 64,66 and 68,70, respectively. Each bolster
pocket 60,62 has
an inclined face, or damper seat 72, that mates with a similarly inclined
hypotenuse face 74 of the
damper wedge, 64, 66, 68 and 70. Wedges 64,66 each sit over a first, inboard
corner spring 76,
78, and wedges 68, 70 each sit over a second, outboard corner spring 80, 82.
Angled faces 74 of
wedges 64, 66 and 68, 70 ride against the angled faces of respective seats 72.
A middle end spring 96 bears on the underside of a land 98 located
intermediate bolster
pockets 60 and 62. The top ends of the central row of springs, 100, seat under
the main central
portion 102 of the end of bolster 24. In this four corner arrangement, each
damper is individually
sprung by one or another of the springs in the spring group. The static
compression of the springs
under the weight of the car body and lading tends to act as a spring loading
to bias the damper to
act along the slope of the bolster pocket to force the friction surface
against the sideframe.
Friction damping is provided when the vertical sliding faces 90 of the
friction damper wedges 64,
66 and 68, 70 ride up and down on friction wear plates 92 mounted to the
inwardly facing surfaces
of sideframe columns 36. In this way the kinetic energy of the motion is, in
some measure,
converted through friction to heat. This friction may tend to damp out the
motion of the bolster
relative to the sideframes. When a lateral perturbation is passed to wheels 50
by the rails, rigid
axles 48 may tend to cause both sideframes 26 to deflect in the same
direction. The reaction of
sideframes 26 is to swing, like pendula, on the upper rockers. The weight of
the pendulum and the
reactive force arising from the twisting of the springs may then tend to urge
the sideframes back to
their initial position. The tendency to oscillate harmonically due to track
perturbations may tend
to be damped out by the friction of the dampers on the wear plates 92.
As compared to a bolster with single dampers, such as may be mounted on the
sideframe
centerline as shown in Figure le, for example, the use of doubled dampers such
as spaced apart
pairs of dampers 64,68 may tend to give a larger moment arm, as indicated by
dimension "2M" in
Figure id, for resisting parallelogram deformation of truck 22 more generally.
Use of doubled
dampers may yield a greater restorative "squaring" force to return the truck
to a square orientation
than for a single damper alone with the restorative bias, namely the squaring
force, increasing with
increasing deflection. That is, in parallelogram deformation, or lozenging,
the differential
compression of one diagonal pair of springs (e.g., inboard spring 76 and
outboard spring 82 may
be more pronouncedly compressed) relative to the other diagonal pair of
springs (e.g., inboard
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spring 78 and outboard spring 80 may be less pronouncedly compressed than
springs 76 and 82)
tends to yield a restorative moment couple acting on the sideframe wear
plates. This moment
couple tends to rotate the sideframe in a direction to square the truck, (that
is, in a position in
which the bolster is perpendicular, or "square", to the sideframes). As such,
the truck is able to
flex, and when it flexes the dampers co-operate in acting as biased members
working between the
bolster and the side frames to resist parallelogram, or lozenging, deformation
of the side frame
relative to the truck bolster and to urge the truck back to the non-deflected
position.
The foregoing explanation has been given in the context of trucks 20 and 22,
each of which
has a spring group that has three rows facing the sideframe columns. The
restorative moment
couple of a four-cornered damper layout can also be explained in the context
of a truck having a 2
row spring group arrangement facing the dampers, as in truck 400 of Figures
14a to 14e. For the
purposes of conceptual visualisation, the normal force on the friction face of
any of the dampers
can be taken as a pressure field whose effect can be approximated by a point
load acting at the
centroid of the pressure field and whose magnitude is equal to the integrated
value of the pressure
field over its area. The center of this distributed force, acting on the
inboard friction face of
wedge 440 against column 428 can be thought of as a point load offset
transversely relative to the
diagonally outboard friction face of wedge 443 against column 430 by a
distance that is nominally
twice dimension `L' shown in the conceptual sketch of Figure lk. In the
example of Figure 14a,
this distance, 2L, is about one full diameter of the large spring coils in the
spring set. The
restoring moment in such a case would be, conceptually, MR = [(F1 F3) ¨ (F2
F4)]L. This
may be expressed MR = 4k,Tan(e)Tan(8)L, where 0 is the primary angle of the
damper (generally
illustrated as a herein), and k, is the vertical spring constant of the coil
upon which the damper sits
and is biased.
In the various arrangements of spring groups 2 x 4, 3 x 3, 3:2:3 or 3 x 5
group, dampers
may be mounted over each of four corner positions. The portion of spring force
acting under the
damper wedges may be in the 25 ¨ 50 % range for springs of equal stiffness. If
not of equal
stiffness, the portion of spring force acting under the dampers may be in the
range of perhaps 20 %
to 35 %. The coil groups can be of unequal stiffness if inner coils are used
in some springs and
not in others, or if springs of differing spring constant are used.
An enhanced tendency to encourage squareness at the bolster to sideframe
interface (i.e.,
through the use of four cornered damper groups) may tend to reduce reliance on
squareness at the
pedestal to wheelset axle interface, and turn, may tend to provide an
opportunity to employ a
torsionally compliant (about the vertical axis) axle to pedestal interface
assembly, and to permit a
measure of self steering.
The bearing plate, namely wear plate 92 (Figure la) is significantly wider
than the through
thickness of the sideframes more generally, as measured, for example, at the
pedestals, and may
CA 02488960 2004-12-03
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tend to be wider than has been conventionally common. This additional width
corresponds to the
additional overall damper span width measured fully across the damper pairs,
plus lateral travel as
noted above, typically allowing 1 1/2 (+/-) inches of lateral travel of the
bolster relative to the
sideframe to either side of the undeflected central position. That is, rather
than having the width
of one coil, plus allowance for travel, plate 92 may have the width of three
coils, plus allowance to
accommodate 1 1/2 (+/-) inches of travel to either side for a total, double
amplitude travel of 3" (+/-
). Bolster 24 has inboard and outboard gibs 106, 108 respectively, that bound
the lateral motion of
bolster 24 relative to sideframe columns 36. This motion allowance may be in
the range of +/- 1
1/8 to 1 3/4 in., and may be in the range of 1 3/16 to 1 9/16 in., and can be
set, for example, at 1 1/2 in.
or 1 1/4 in. of lateral travel to either side of a neutral, or centered,
position when the sideframe is
undeflected.
The lower ends of the springs of the entire spring group, identified generally
as 58, seat in
lower spring seat 52. Lower spring seat 52 may be laid out as a tray with an
upturned rectangular
peripheral lip. Although truck 22 employs a spring group in a 3 x 3
arrangement, this is intended
to be generic, and to represent a range of variations. They may represent 3 x
5, 2 x 4, 3:2:3 or
2:3:2 arrangement, or some other, and may include a hydraulic snubber, or such
other arrangement
of springs may be appropriate for the given service for the railcar for which
the truck is intended.
Figures 2a ¨ 2g
The rocking interface surface of the bearing adapter might have a crown, or a
concave
curvature, like a swing motion truck, by which a rolling contact on the rocker
permits lateral
swinging of the side frame. The bearing adapter to pedestal seat interface
might also have a fore-
and-aft curvature, whether a crown or a depression, and that, for a given
vertical load, this crown
or depression might tend to present a more or less linear resistance to
deflection in the longitudinal
direction, much as a spring or elastomeric pad might do.
For surfaces in rolling contact on a compound curved surface (i.e., having
curvatures in
two directions) as shown and described herein, the vertical stiffness may be
approximated as
infinite (i.e. very large as compared to other stiffnesses); the longitudinal
stiffness in translation at
the point of contact can also be taken as infinite, the assumption being that
the surfaces do not slip;
the lateral stiffness in translation at the point of contact can be taken as
infinite, again, provided
the surfaces do not slip. The rotational stiffness about the vertical axis may
be taken as zero or
approximately zero. By contrast, the angular stiffnesses about the
longitudinal and transverse axes
are non-trivial. The lateral angular stiffnesses may tend to determine the
equivalent pendulum
stiffnesses for the sideframe more generally.
The stiffness of a pendulum is directly proportional to the weight on the
pendulum.
Similarly, the drag on a rail car wheel, and the wear to the underlying track
structure, is a function
of the weight borne by the wheel. For this reason, the desirability of self
steering may be greatest
CA 02488960 2004-12-03
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for a fully laden car, and a pendulum may tend to maintain a general
proportionality between the
weight borne by the wheel and the stiffness of the self-steering mechanism as
the lading increases.
Truck performance may vary with the friction characteristics of the damper
surfaces.
Wedges have been used that have tended to employ dampers in which the dynamic
and static
coefficients of friction may have been significantly different, yielding a
stick-slip phenomenon
that may not have been entirely advantageous. In some embodiments herein the
feature of a self-
steering capability may be combined with dampers that have a reduced tendency
to stick-slip
operation. Furthermore, while bearing adapters may be formed of relatively low
cost materials,
such as cast iron, in some embodiments an insert of a different material may
be used for the
to
rocker. Further, some embodiments may employ a member that may tend to center
the rocker on
installation, and that may tend to perform an auxiliary centering function to
tend to urge the rocker
to operate from an at rest minimum energy position.
Figures 2a ¨ 2g show an embodiment of bearing adapter and pedestal seat
assembly. Bearing
adapter 44 has a lower portion 112 that is formed to accommodate, and to seat
upon, bearing 46, that
is itself mounted on the end of a shaft, namely an end of axle 48. Bearing
adapter 44 has an upper
portion 114 that has a centrally located, upwardly protruding fitting in the
nature of a male bearing
adapter interface portion 116. A mating fitting, in the nature of a female
rocker seat interface portion
118 may be rigidly mounted within the roof 120 of the sideframe pedestal. To
that end, laterally
extending lugs 122 are mounted centrally with respect to pedestal roof 120.
The upper fitting 40,
whichever type it may be, has a body that may be in the form of a plate 126
having, along its
longitudinally extending, lateral margins a set of upwardly extending lugs or
ears, or tangs 124
separated by a notch, that bracket, and tightly engage lugs 122, thereby
locating upper fitting 40 in
position, with the back of the plate 126 of fitting 40 abutting the flat, load
transfer face of roof 120.
Upper fitting 40 may be a pedestal seat fitting with a hollowed out female
bearing surface, namely
portion 118. As shown in Figure 2g, when the sideframes are lowered over the
wheel sets, the end
reliefs, or channels 128 lying between the bearing adapter corner abutments
132 seat between the
respective side frame pedestal jaws 130. With the sideframes in place, bearing
adapter 44 is thus
captured in position with the male and female portions (116 and 118) of the
adapter interface in
mating engagement.
Male portion 116 (Figure 2d) has been formed to have a generally upwardly
facing surface
142 that has both a first curvature ri to permit rocking in the longitudinal
direction, and a second
curvature r2 (Figure 2c) to permit rocking (i.e., swing motion of the
sideframe) in the transverse
direction. Similarly, in the general case, female portion 118 has a surface
having a first radius of
curvature R1 in the longitudinal direction, and a second radius of curvature
R2 in the transverse
direction. The engagement of n with R1 may tend to permit a rocking motion in
the longitudinal
direction, with resistance to rocking displacement being proportional to the
weight on the wheel.
CA 02488960 2004-12-03
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That is to say, the resistance to angular deflection is proportional to weight
rather than being a fixed
spring constant. This may tend to yield passive self-steering in both the
light car and fully laden
conditions. This relationship is shown in Figures 2d and 2e. Figure 2d shows
the centered, or at rest,
non-deflected position of the longitudinal rocking elements. Figure 2e shows
the rocking elements at
their condition of maximum longitudinal deflection. Figure 2d represents a
local, minimum potential
energy condition for the system. Figure 2e represents a system in which the
potential energy has
been increased by virtue of the work done by force F acting longitudinally in
the horizontal plane
through the center of the axle and bearing, CB., which will tend to yield an
incremental increase in the
height of the pedestal. Put differently, as the axle is urged to deflect by
the force, the rocking motion
may tend to raise the car, and thereby to increase its potential energy.
The limit of travel in the longitudinal direction is reached when the end face
134 of bearing
adapter 44 extending between corner abutments 132, contacts one or another of
travel limiting
abutment faces 136 of the thrust blocks of jaws 130. In general, the
deflection may be measured
either by the angular displacement of the axle centreline, 01, or by the
angular displacement of the
rocker contact point on radius ri, shown as 02. End face 134 of bearing
adapter 44 is planar, and is
relieved, or inclined, at an angle ri from the vertical. As shown in Figure
2g, abutment face 136 may
have a round, cylindrical arc, with the major axis of the cylinder extending
vertically. A typical
maximum radius R3 for this surface is 34 inches. When bearing adapter 44 is
fully deflected through
angle ri, end face 134 is intended to meet abutment face 136 in line contact.
When this occurs,
further longitudinal rocking motion of the male surface (of portion 116)
against the female surface
(of portion 118) is inhibited. Thus jaws 130 constrain the arcuate deflection
of bearing adapter 44 to
a limited range. A typical range for t might be about 3 degrees of arc. A
typical maximum value of
along may be about +/- 3/16" to either side of the vertical, at rest, center
line.
Similarly, as shown in Figures 2b and 2c, in the transverse direction, the
engagement of r2
with R2 may tend to permit lateral rocking motion, as may be in the manner of
a swing motion truck.
Figure 2b shows a centered, at rest, minimum potential energy position of the
lateral rocking system.
Figure 2c shows the same system in a laterally deflected condition. In this
instance 62 is roughly
(Lpendulum r2)Sin", where, for small angles Sirup is approximately equal to v.
Lpendulum may be
taken as the at rest difference in height between the center of the bottom
spring seat, 52, and the
contact interface between the male and female portions 116 and 118.
When a lateral force is applied at the centerplate of the truck bolster, a
reaction force is,
ultimately, provided at the meeting of the wheels with the rail. The lateral
force is transmitted from
the bolster into the main spring groups, and then into a lateral force in the
spring seats to deflect the
bottom of the pendulum. The reaction is carried to the bearing adapter, and
hence into the top of the
pendulum. The pendulum will then deflect until the weight on the pendulum,
multiplied by the
moment arm of the deflected pendulum is sufficient to balance the moment of
the lateral moment
CA 02488960 2004-12-03
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couple acting on the pendulum.
This bearing adapter to pedestal seat interface assembly is biased by gravity
acting on the
pendulum toward a central, or "at rest" position, where there is a local
minimum of the potential
energy in the system. The fully deflected position shown in Figure 2c may
correspond to a deflection
from vertical of the order of less than 10 degrees (and preferably less than 5
degrees) to either side of
center, the actual maximum being determined by the spacing of gibbs 106 and
108 relative to plate
104. Although in general R1 and R2 may differ, so the female surface is an
outside section of a torus,
for R1 and R2 may be the same, i.e., so that the bearing surface of the female
fitting is formed as a
portion of a spherical surface, having neither a major nor a minor axis, but
merely being formed on a
spherical radius. R1 and R2 give a self-centering tendency. That tendency may
be quite gentle.
Further, and again in the general condition, the smallest of R1 and R2 may be
equal to or larger than
the largest of n and r2. If so, then the contact point may have little, if
any, ability to transmit torsion
acting about an axis normal to the rocking surfaces at the point of contact,
so the lateral and
longitudinal rocking motions may tend to be torsionally de-coupled, and hence
it may be said that
relative to this degree of freedom (rotation about the vertical, or
substantially vertical axis normal to
the rocking contact interface surfaces) the interface is torsionally compliant
(that is, the resistance to
torsional deflection about the axis through the surfaces at the point of
contact may tend to be much
smaller than, for example, resistance to lateral angular deflection). For
small angular deflections, the
torsional stiffness about the normal axis at the contact point, this condition
may sometimes be
satisfied even where the smaller of the female radii is less than the largest
male radius. Although it
is possible for ri and r2 to be the same, such that the crowned surface of the
bearing adapter (or the
pedestal seat, if the relationship is inverted) is a portion of a spherical
surface, in the general case r1
and r2 may be different, with ri perhaps tending to be larger, possibly
significantly larger, than r2. In
general, whether or not r1 and r2 are equal, R1 and R2 may be the same or
different. Where r1 and r2
are different, the male fitting engagement surface may be a section of the
surface of a torus. It may
also be noted that, provided the system may tend to return to a local minimum
energy state (i.e., that
is self-restorative in normal operation) in the limit either or both of R1 and
R2 may be infinitely large
such that either a cylindrical section is formed or, when both are infinitely
large, a planar surface may
be formed. In the further alternative, it may be that n = r2, and R1 = R2. In
one embodiment ri may
be the same as r2, and may be about 40 inches (+/- 5") and R1 may the same as
R2, and both may be
infinite such that the female surface is planar.
Other embodiments of rocker geometry may be considered. In one embodiment R1=
R2 =15
inches, r1 = 8 5/8 inches and r2 = 5". In another embodiment, R1 = R2 = 15
inches, and ri = 10" and
r2 = 8 5/8" (+/-). In another embodiment r1 = 8 5/8, r2 = 5", RI = R2 = 12" in
still another embodiment
n = 12 1/23), r2 = 8 5/8 and R1 = R2 = 15".
The radius of curvature of the male longitudinal rocker, r1, may be less than
60 inches, and
CA 02488960 2004-12-03
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may lie in the range of 5 to 50 inches, may lie in the range of 8 to 40
inches, and may be about 15
inches. R1 may be infinite, or may be less than 100 inches, and may be in the
range of 10 to 60
inches, or in the narrower range of 12 to 40 inches, and may be in the range
of 11/10 to 4 times the
size of r1.
The radius of curvature of the male lateral rocker, r2, may be between 30 and
50 inches.
Alternatively in another type of truck, r2, may be less than about 25 or 30
in., and may lie in the range
of about 5 to 20 inches. r2 may lie in the range of about 8 to 16 inches, and
may be about 10 inches.
Where line contact rocking motion is used, r2 may perhaps be somewhat smaller
than otherwise,
perhaps in the range of 3 to 10 inches, and perhaps being about 5 inches.
R2 may be less than 60 inches, and may be less than about 25 or 30 inches,
then being less
than half the 60 inch crown radius noted above. Alternatively, R2 may lie in
the range of 6 to 40
inches, and may lie in the range of 5 to 15 inches in the case of rolling line
contact. R2 may be
between 1 1/2 to 4 times as large as r2. In one embodiment R2 may be roughly
twice as large as r2,
(+/- 20 %). Where line contact is employed, R2 may be in the range of 5 to 20
inches, or more
narrowly, 8 to 14 inches.
Where a spherical male rocker is used on a spherical female cap, in some
embodiments the
male radius may be in the range of 8¨ 13 in., and may be about 9 in.; the
female radius may be in the
range of 11 ¨16 in., and may be about 12 in. Where a torus, or elliptical
surface is employed, in one
embodiment the lateral male radius may be about 7 in., the longitudinal male
radius may be about 10
inches, the lateral female radius may be about 12 in. and the longitudinal
female radius may be about
15 in. Where a flat female rocker surface is used, and a male spherical
surface is used, the male
radius of curvature may be in the range of about 20 to about 50 in., and may
lie in the narrower range
of 30 to 40 in.
Many combinations are possible, depending on loading, intended use, and rocker
materials.
In each case the mating male and female rocker surfaces may tend to be chosen
to yield a physically
reasonable pairing in terms of expected loading, anticipated load history, and
operational life. These
may vary.
The rocker surfaces herein may tend to be formed of a relatively hard
material, which may be
a metal or metal alloy material, such as a steel or a material of comparable
hardness and toughness.
Such materials may have elastic deformation at the location of rocking contact
in a manner analogous
to that ofjournal or ball bearings. Nonetheless, the rockers may be taken as
approximating the ideal
rolling point or line contact (as may be) of infinitely stiff members. This is
to be distinguished from
materials in which deflection of an elastomeric element be it a pad, or block,
of whatever shape, may
be intended to determine a characteristic of the dynamic or static response of
the element.
In one embodiment the lateral rocking constant for a light car may be in the
range of about
48,000 to 130,000 in-lbs per radian of angular deflection of the side frame
pendulum, or, 260,000 to
CA 02488960 2004-12-03
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700,000 in-lbs per radian for a fully laded car, or more generically, about
0.95 to 2.6 in-lbs per radian
per pound of weight borne by the pendulum. Alternatively, for a light (i.e.,
empty) car the stiffness of
the pendulum may be in the range 3,200 to 15,000 lbs per inch, and 22,000 to
61,000 lbs per inch for
a fully laden 110 ton truck, or, more generically, in the range of 0.06 to
0.160 lbs per inch of lateral
deflection per pound weight borne by the pendulum, as measured at the bottom
spring seat.
The male and female surfaces may be inverted, such that the female engagement
surface is
formed on the bearing adapter, and the male engagement surface is formed on
the pedestal seat. It is
a matter of terminology which part is actually the "seat", and which is the
"rocker". Sometimes the
seat may be assumed to be the part that has the larger radius, and which is
usually thought of as being
the stationary reference, while the rocker is taken to be the part with the
smaller radius, that "rocks"
on the stationary seat. However, this is not always so. At root, the
relationship is of mating parts,
whether male or female, and there is relative motion between the parts, or
fittings, whether the fittings
are called a "seat" or a "rocker". The fittings mate at a force transfer
interface. The force transfer
interface moves as the parts that co-operate to define the rocking interface
rock on each other,
whichever part may be, nominally, the male part or the female part. One of the
mating parts or
surfaces is part of the bearing adapter, and another is part of the pedestal.
There may be only two
mating surfaces, or there may be more than two mating surfaces in the overall
assembly defining the
dynamic interface between the bearing adapter and the pedestal fitting, or
pedestal seat, however it
may be called.
Both female radii R1 and R2 may not be on the same fitting, and both male
radii ri and r2 may
not be on the same fitting. That is, they may be combined to form saddle
shaped fittings in which the
bearing adapter has an upper surface that has a male fitting in the nature of
a longitudinally extending
crown with a laterally extending axis of rotation, having the radius of
curvature is r1, and a female
fitting in the nature of a longitudinally extending trough having a lateral
radius of curvature R2.
Similarly, the pedestal seat fitting may have a downwardly facing surface that
has a transversely
extending trough having a longitudinally oriented radius of curvature RI, for
engagement with r1 of
the crown of the bearing adapter, and a longitudinally running, downwardly
protruding crown having
a transverse radius of curvature r2 for engagement with R2 of the trough of
the bearing adapter.
In a sense, a saddle shaped surface is both a seat and a rocker, being a seat
in one direction,
and a rocker in the other. As noted above, the essence is that there are two
small radii, and two large
(or possibly even infinite) radii, and the surfaces form a mating pair that
engage in rolling contact in
both the lateral and longitudinal directions, with a central local minimum
potential energy position to
which the assembly is biased to return. It may also be noted that the saddle
surfaces can be inverted
such that the bearing adapter has r2 and 111, and the pedestal seat fitting
has r1 and R2. In either case,
the smallest of R1 and R2 may be larger than, or equal to, the largest of r1
and r2, and the mating
saddle surfaces may tend to be torsionally uncoupled as noted above.
CA 02488960 2004-12-03
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Figures 3a
Figure 3a shows an alternate embodiment of wheelset to sideframe interface
assembly,
indicated most generally as 150. The pedestal region of sideframe 151, as
shown in Figure 3a, is
substantially similar to those shown in the previous examples, and may be
taken as being the same
except insofar as may be noted. Similarly, bearing 152 may be taken as
representing the location of
the end of a wheelset more generally, with the wheelset to sideframe interface
assembly including
those items, members or elements that are mounted between bearing 152 and
sideframe 151. Bearing
adapter 154 may be generally similar to bearing adapter 44 in terms of its
lower structure for seating
on bearing 152. As with the bodies of the other bearing adapters described
herein, the body of
bearing adapter 154 may be a casting or a forging, or a machined part, and may
be made of a material
that may be a relatively low cost material, such as cast iron or steel, and
may be made in generally the
same manner as bearing adapters have been made heretofore. Bearing adapter 154
may have a bi-
directional rocker 153 employing a compound curvature of first and second
radii of curvature
according to one or another of the possible combinations of male and female
radii of curvature
discussed herein. Bearing adapter 154 may differ from those described above in
that the central body
portion 155 of the adapter has been trimmed to be shorter longitudinally, and
the inside spacing
between the corner abutment portions has been widened somewhat, to accommodate
the installation
of an auxiliary centering device, or centering member, or centrally biased
restoring member in the
nature of, for example, elastomeric bumper pads, such as those identified as
resilient pads, or
members 156. Members 156 may be considered a form of restorative centering
element, and may
also be termed "snubbers" or "bumper" pads. A pedestal seat fitting having a
mating rocking surface
for permitting lateral and longitudinal rocking, is identified as 158. As with
the other pedestal seat
fittings shown and described herein, fitting 158 may be made of a hard metal
material, which may be
a grade of steel. The engagement of the rocking surfaces may, again, tend to
have low resistance to
torsion about a predominantly vertical axis through the point of contact.
Figure 3b
In Figure 3b, a bearing adapter 160 is substantially similar to bearing
adapter 154, but differs
in having a central recess, socket, cavity or accommodation, indicated
generally as 161, for receiving
an insert identified as a first, or lower, rocker member 162. As with bearing
adapter 154, the main, or
central portion of the body 159 of bearing adapter 160 may be of shorter
longitudinal extent than
might otherwise be the case, being truncated, or relieved, to accommodate
resilient members 156.
Accommodation 161 may have a plan view form whose periphery may include one or
more
keying, or indexing, features or fittings, of which cusps 163 may be
representative. Cusps 163 may
receive mating keying, or indexing, features or fittings of rocker member 162,
of which lobes 164
may be taken as representative examples. Cusps 163 and lobes 164 may fix the
angular orientation of
the lower, or first, rocker member 162 such that the appropriate radii of
curvature may be presented in
CA 02488960 2004-12-03
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each of the lateral and longitudinal directions. For example, cusps 163 may be
spaced unequally
about the periphery of accommodation 161 (with lobes 164 being correspondingly
spaced about the
periphery of the insert member 162) in a specific spacing arrangement to
prevent installation in an
incorrect orientation, (such as 90 degrees out of phase). For example, one
cusp may be spaced 80
degrees of arc about the periphery from one neighbouring cusp, and 100 degrees
of arc from another
neighbouring cusp, and so on to form a rectangular pattern. Many variations
are possible.
While body 159 of bearing adapter 160 may be made of cast iron or steel, the
insert, namely
first rocker member 162, may be made of a different material that may have
higher hardness. That
different material may present a hardened metal rocker surface such as may
have been manufactured
by a different process. For example, the insert, member 162, may be made of a
metal, such as a tool
steel, or of a steel such as may be used in the manufacture of ball bearings.
The material may have a
Young's modulus in excess of 2.5 x 107 p.s.1., such as may be about 3.0 x 107
p.s.l. such as might be
typical of a steel. The material may have a yield stress in excess of 100
kpsi, and that yield stress
may be in excess of 200 kpsi in some embodiments. Furthermore, upper surface
165 of insert
member 162, which includes that portion that is in rocking engagement with the
mating pedestal seat
168, may be machined or otherwise formed to a high degree of smoothness, akin
to a ball bearing
surface, and may be heat treated, to give a finished bearing part
approximating ideal rolling point or
line contact rather then an interface relying upon deflection of the body of
the element of an
elastomeric pad or block. That is, the rocking stiffness may rely on the
geometry of the pendulum,
namely the radii of the curvature of the rocking surfaces and the length of
the pendulum as distinct
from elastic deflection of the material, as in an elastomeric rubber or
polymer based pad for example
and that may demonstrate significant hysteresis. Put differently, the vertical
stiffness of the rocker,
based on its bulk material properties, may be two or more orders of magnitude
greater than its lateral
rocking stiffness, which is based on geometry, such that approximation of the
vertical stiffness as
being infinite by comparison is physically reasonable. Similarly, the lateral
stiffness of the rocker in
lateral shear, as manifested by bodily deflection of the rocker elements due
to the bulk properties of
the rocker materials, may be taken as being at least two orders of magnitude
(if not many orders of
magnitude) greater than the lateral rocking stiffness of the pendulum such
that it is physically
reasonable to consider the material to approximate infinite stiffness as
compared to the rocker
geometry. The foregoing commentary may be taken as applying to each of the
embodiments
described herein in which there is reference to rolling point or line contact.
Similarly, pedestal seat 168 may be made of a hardened material, such as a
tool steel or a steel
from which bearings are made, formed to a high level of smoothness, and heat
treated as may be
appropriate of appropriate modulus of elasticity and yield stress, which may
be in the ranges
discussed above, having a surface formed to mate with surface 165 of rocker
member 162.
Alternatively, pedestal seat 168 may have an accommodation indicated as 167,
and an insert member,
CA 02488960 2004-12-03
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identified as upper or second rocker member 166, analogous to accommodation
161 and insert
member 162, with keying or indexing such as may tend to cause the parts to
seat in the correct
orientation. Member 166 may be formed of a hard material in a manner similar
to member 162, and
may have a downward facing rocking surface 157, which may be machined or
otherwise formed to a
high degree of smoothness, akin to a ball or roller bearing surface, and may
be heat treated, to give a
finished bearing part surface for mating, rocking engagement with surface 165.
Where rocker
member 162 has both male radii, and the female radii of curvature are both
infinite such that the
female surface is planar, a wear member having a planar surface such as a
spring clip may be
mounted in a sprung interference fit in the pedestal roof in lieu of pedestal
seat 168. In one
embodiment, the spring clip may be a clip on "Dyna-Clip" (t.m.) pedestal roof
wear plate such as
supplied by TransDyne Inc. Such a clip is shown in an isometric view in Figure
8a as item 354.
Figure 3e
Figure 3e shows an alternate embodiment of wheelset to sideframe interface
assembly,
indicated generally as 170. Assembly 170 may include a bearing adapter 171, a
pair of resilient
members 156, a rocking assembly that may include a boot, resilient ring or
retainer, 172, a first rocker
member 173, and a second rocker member 174. A pedestal seat may be provided to
mount in the roof
of the pedestal as described above, or second rocker member 174 may mount
directly in the pedestal
roof.
Bearing adapter 171 is generally similar to bearing adapter 44, or 154, in
terms of its lower
structure for seating on bearing 152. The body of bearing adapter 171 may be a
casting or a forging,
or a machined part, and may be made of a material that may be a relatively low
cost material, such as
cast iron or steel. Bearing adapter 171 may be provided with a central recess,
socket, cavity or
accommodation, indicated generally as 176, for receiving rocker member 173 and
rocker member
174, and retainer 172. The ends of the main portion of the body of bearing
adapter 171 may be of
relatively short extent to accommodate resilient members 156. Accommodation
176 may have the
form of a circular opening, that may have a radially inwardly extending flange
177, whose upwardly
facing surface 178 defines a circumferential land upon which to seat first
rocker member 173. Flange
177 may also include drain holes 178, such as may be 4 holes formed on 90
degree centers, for
example. Rocker member 173 has a spherical engagement surface. First rocker
member 173 may
include a thickened central portion, and a thinner radially distant peripheral
portion, having a lower
radial edge, or margin, or land, for seating upon, and for transferring
vertical loads into, flange 177.
In an alternate embodiment, a non-galling, relatively soft annular gasket, or
shim, whether made of a
suitable brass, bronze, copper, or other material may be employed on flange
177 under the land. First
rocker member 173 may be made of a different material from the material from
which the body of
bearing adapter 156 is made more generally. That is to say, rocker member 173
may be made of a
hard, or hardened material, such as a tool steel or a steel such as might be
used in a bearing, that may
CA 02488960 2004-12-03
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be harder and may be finished to a generally higher level of precision, and to
a finer degree of surface
roughness than the body of bearing adapter 156 more generally. Such a material
may be suitable for
rolling contact operation under high contact pressures.
Second rocker member 174 may be a disc of circular shape (in plan view) or
other suitable
shape having an upper surface for seating in pedestal seat 168, or, in the
event a pedestal seat
member is not used, then formed directly to mate with the pedestal roof having
an integrally formed
seat. First rocker member 173 may have an upper, or rocker surface 175, having
a profile such as
may give bi-directional lateral and longitudinal rocking motion when used in
conjunction with the
mating second, or upper rocker member, 174. Second rocker member 174 may be
made of a
different material from the material from which the body of bearing adapter
171, or the pedestal seat,
is made more generally. Second rocker member 174 may be made of a hard, or
hardened material,
such as a tool steel or a steel such as might be used in a bearing, that may
be harder and may be
finished to a generally higher level of precision, and to a finer degree of
surface roughness than the
body of sideframe 151 more generally. Such a material may be suitable for
rolling contact operation
under high contact pressures, particularly as when operated in conjunction
with first rocker member
173. Where an insert of dissimilar material is used, that material may tend to
be rather more costly
than the cast iron or relatively mild steel from which bearing adapters may
otherwise tend to be made.
Further still, an insert of this nature may be removed and replaced when worn,
either on the basis of a
scheduled rotation, or as the need may arise.
Resilient member 172 may be made of a composite or polymeric material, such as
a
polyurethane. Resilient member 172 may also have apertures, or reliefs 179
such as may be placed in
a position for co-operation with corresponding drain holes 178. The wall
height of resilient member
172 may be sufficiently tall to engage the periphery of first rocker member
173. Further, a portion of
the radially outwardly facing peripheral edge of the second, upper, rocking
member 174, may also lie
within, or may be partially overlapped by, and may possibly slightly
stretchingly engage, the upper
margin of resilient member 172 in a close, or interference, fit manner, such
that a seal may tend to be
formed to exclude dirt or moisture. In this way the assembly may tend to form
a closed unit. In that
regard, such space as may be formed between the first and second rockers 173,
174 inside the dirt
exclusion member may be packed with a lubricant, such as a lithium or other
suitable grease.
Figures 4a ¨ 4e
As shown in Figures 4a ¨ 4e, resilient members 156 may have the general shape
of a channel,
having a central, or back, or transverse, or web portion 181, and a pair of
left and right hand, flanking
wing portions 182, 183. Wing portions 182 and 183 may tend to have downwardly
and outwardly
tending extremities that may tend to have an arcuate lower edge such as may
seat over the bearing
casing. The inside width of wing portions 182 and 183 may be such as to seat
snugly about the sides
of thrust blocks 180. A transversely extending lobate portion 185, running
along the upper margin of
CA 02488960 2004-12-03
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web portion 181, may seat in a radiused rebate 184 between the upper margin of
thrust blocks 180
and the end of pedestal seat 168. The inner lateral edge 186 of lobate portion
185 may tend to be
chamfered, or relieved, to accommodate, and to seat next to, the end of
pedestal seat 168.
It may be desirable for the rocking assembly at the wheelset to sideframe
interface to tend to
maintain itself in a centered condition. As noted, the torsionally de-coupled
bi-directional rocker
arrangements disclosed herein may tend to have rocking stiffnesses that are
proportional to the weight
placed upon the rocker. Where a longitudinal rocking surface is used to permit
self-steering, and
the truck is experiencing reduced wheel load, (such as may approach wheel
lift), or where the car
is operating in the light car condition, it may be helpful to employ an
auxiliary restorative
centering element that may include a biasing element tending to urge the
bearing adapter to a
longitudinally centered position relative to the pedestal roof, and whose
restorative tendency may
be independent of the gravitational force experienced at the wheel. That is,
when the bearing
adapter is under less than full load, or is unloaded, it may be desirable to
maintain a bias to a
central position. Resilient members 156 described above may operate to urge
such centering.
Figures 3c and 3d illustrate the spatial relationship of the sandwich formed
by (a) the bearing
adapter, for example, bearing adapter 154; (b) the centering member, such as,
for example, resilient
members 156; and (c) the pedestal jaw thrust blocks, 180. Ancillary details
such as, for example,
drain holes or phantom lines to show hidden features have been omitted from
Figures 3c and 3d for
clarity. When resilient member 156 is in place, bearing adapter 154 (or 171,
as may be); may tend to
be centered relative to jaws 180. As installed, the snubber (member 156) may
seat closely about
the pedestal jaw thrust lug, and may seat next to the bearing adapter end wall
and between the
bearing adapter corner abutments in a slight interference fit. The snubber may
be sandwiched
between, and may establish the spaced relative position of, the thrust lug and
the bearing adapter
and may provide an initial central positioning of the mating rocker elements
as well as providing a
restorative bias. Although bearing adapter 154 may still rock relative to the
sideframe, such rocking
may tend to deform (typically, locally to compress) a portion of member 156,
and, being elastic,
member 156 may tend to urge bearing adapter 154 toward a central position,
whether there is much
weight on the rocking elements or not. Resilient member 156 may have a
restorative force-deflection
characteristic in the longitudinal direction that is substantially less stiff
than the force deflection
characteristic of the fully loaded longitudinal rocker (perhaps one to two
orders of magnitude less),
such that, in a fully loaded car condition, member 156 may tend not
significantly to alter the rocking
behaviour. In one embodiment member 156 may be made of a polyurethane having a
Young's
modulus of some 6,500 p.s.i. In another embodiment the Young's modulus may be
about 13,000
p.s.i. The Young's modulus of the elastomeric material may be in the range of
4 to 20 k.p.s.i. The
placement of resilient members 156 may tend to center the rocking elements
during installation. In
one embodiment, the force to deflect one of the snubbers may be less than 20 %
of the force to
CA 02488960 2004-12-03
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deflect the rocker a corresponding amount under the light car (i.e., unloaded)
condition, and may,
for small deflections, have an equivalent force/deflection curve slope that
may be less than 10 %
of the force deflection characteristic of the longitudinal rocker.
Figure 5
Thus far only primary wedge angles have been discussed. Figure 5 shows an
isometric
view of an end portion of a truck bolster 210. As with all of the truck
bolsters shown and
discussed herein, bolster 210 is symmetrical about the central longitudinal
vertical plane of the
bolster (i.e., cross-wise relative to the truck generally) and symmetrical
about the vertical mid-
span section of the bolster (i.e., the longitudinal plane of symmetry of the
truck generally,
coinciding with the railcar longitudinal center line). Bolster 210 has a pair
of spaced apart bolster
pockets 212,214 for receiving damper wedges 216, 218. Pocket 212 is laterally
inboard of pocket
214 relative to the side frame of the truck more generally. Wear plate inserts
220, 222 are
mounted in pockets 212, 214 along the angled wedge face.
As can be seen, wedges 216, 218 have a primary angle, a as measured between
vertical
and the angled trailing vertex 228 of outboard face 230. For the embodiments
discussed herein,
primary angle a may tend to lie in the range of 35 ¨ 55 degrees, possibly
about 40 - 50 degrees.
This same angle a is matched by the facing surface of the bolster pocket, be
it 212 or 214. A
secondary angle 11 gives the inboard, (or outboard), rake of the sloped
surface 224, (or 226) of
wedge 216 (or 218). The true rake angle can be seen by sighting along plane of
the sloped face
and measuring the angle between the sloped face and the planar outboard face
230. The rake
angle is the complement of the angle so measured. The rake angle may tend to
be greater than 5
degrees, may lie in the range of 5 to 20 degrees, and is preferably about 10
to 15 degrees. A
modest rake angle may be desirable.
When the truck suspension works in response to track perturbations, the damper
wedges
may tend to work in their pockets. The rake angles yield a component of force
tending to bias the
outboard face 230 of outboard wedge 218 outboard against the opposing outboard
face of bolster
pocket 214. Similarly, the inboard face of wedge 216 may tend to be biased
toward the inboard
planar face of inboard bolster pocket 212. These inboard and outboard faces of
the bolster pockets
may be lined with a low friction surface pad, indicated generally as 232. The
left hand and right
hand biases of the wedges may tend to keep them apart to yield the full moment
arm distance
intended, and, by keeping them against the planar facing walls, may tend to
discourage twisting of
the dampers in the respective pockets.
Bolster 210 includes a middle land 234 between pockets 212, 214, against which
another
spring 236 may work. Middle land 234 is such as might be found in a spring
group that is three
(or more) coils wide. However, whether two, three, or more coils wide, and
whether employing a
central land or no central land, bolster pockets can have both primary and
secondary angles as
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illustrated in the example embodiment of Figure 5a, with or without wear
inserts.
Where a central land, e.g., land 234, separates two damper pockets, the
opposing side
frame column wear plates need not be monolithic. That is, two wear plate
regions could be
provided, one opposite each of the inboard and outboard dampers, presenting
planar surfaces
against which the dampers can bear. The normal vectors of those regions may be
parallel, the
surfaces may be co-planar and perpendicular to the long axis of the side
frame, and may present a
clear, un-interrupted surface to the friction faces of the dampers.
Figure le
Figure le shows an example of a three piece railroad car truck, shown
generally as 250.
Truck 250 has a truck bolster 252, and a pair of sidefiumes 254. The spring
groups of truck 250 are
indicated as 256. Spring groups 256 are spring groups having three springs 258
(inboard corner), 260
(center) and 262 (outboard corner) most closely adjacent to the sideframe
columns 254. A motion
calming, kinematic energy dissipating element, in the nature of a friction
damper 264,266 is mounted
over each of central springs 260.
Friction damper 264, 266 has a substantially planar friction face 268 mounted
in facing,
planar opposition to, and for engagement with, a side frame wear member in the
nature of a wear
plate 270 mounted to sideframe column 254. The base of damper 264,266 defines
a spring seat, or
socket 272 into which the upper end of central spring 260 seats. Damper
264,266 has a third face,
being an inclined slope or hypotenuse face 274 for mating engagement with a
sloped face 276 inside
sloped bolster pocket 278. Compression of spring 260 under an end of the truck
bolster may tend to
load damper 264 or 266, as may be, such that friction face 268 is biased
against the opposing bearing
face of the sideframe column, 280. Truck 250 also has wheelsets whose bearings
are mounted in the
pedestal 284 at either ends of the side frames 254. Each of these pedestals
may accommodate one or
another of the sideframe to bearing adapter interface assemblies described
above and may thereby
have a measure of self steering.
In this embodiment, vertical face 268 of friction damper 264,266 may have a
bearing surface
having a co-efficient of static friction, s, and a co-efficient of dynamic or
kinetic friction, k, that
may tend to exhibit little or no "stick-slip" behaviour when operating against
the wear surface of wear
plate 270. In one embodiment, the coefficients of friction are within 10 % of
each other. In another
embodiment the coefficients of friction are substantially equal and may be
substantially free of stick-
slip behaviour. In one embodiment, when dry, the coefficients of friction may
be in the range of 0.10
to 0.45, may be in the narrower range of 0.15 to 0.35, and may be about 0.30.
Friction damper 264,
266 may have a friction face coating, or bonded pad 286 having these friction
properties, and
corresponding to those inserts or pads described in the context of Figures 6a-
6c, and Figures 7a ¨ 7h.
Bonded pad 286 may be a polymeric pad or coating. A low friction, or
controlled friction pad or
coating 288 may also be employed on the sloped surface of the damper. In one
embodiment that
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coating or pad 288 may have coefficients of static and dynamic friction that
are within 20%, or, more
narrowly, 10 % of each other. In another embodiment, the coefficients of
static and dynamic friction
are substantially equal. The co-efficient of dynamic friction may be in the
range of 0.10 to 0.30, and
may be about 0.20.
Figures 6a to 6c
The bodies of the damper wedges themselves may be made from a relatively
common
material, such as a mild steel or cast iron. The wedges may then be given wear
face members in
the nature of shoes, wear inserts or other wear members, which may be intended
to be consumable
items. In Figure 6a, a damper wedge is shown generically as 300. The
replaceable, friction
modification consumable wear members are indicated as 302, 304. The wedges and
wear
members may have mating male and female mechanical interlink features, such as
the cross-
shaped relief 303 formed in the primary angled and vertical faces of wedge 300
for mating with
the corresponding raised cross shaped features 305 of wear members 302, 304.
Sliding wear
member 302 may be made of a material having specified friction properties, and
may be obtained
from a supplier of such materials as, for example, brake and clutch linings
and the like, such as
Railway Friction Products. The materials may include materials that are
referred to as being non-
metallic, low friction materials, and may include UHMW polymers, and may be
formed as
removable and replaceable pads or blocks or linings.
Although Figures 6a and 6c show consumable inserts in the nature of wear
plates, namely
wear members 302, 304 the entire bolster pocket may be made as a replaceable
part. It may be a
high precision casting, or may include a sintered powder metal assembly having
suitable physical
properties. The part so formed may then be welded into place in the end of the
bolster.
The underside of the wedges described herein, wedge 300 being typical in this
regard, may
have a seat, or socket 307, for engaging the top end of the spring coil,
whichever spring it may be,
spring 262 being shown as typically representative. Socket 307 serves to
discourage the top end
of the spring from wandering away from the intended generally central position
under the wedge.
A bottom seat, or boss, for discouraging lateral wandering of the bottom end
of the spring is
shown in Figure le as item 308. It may be noted that wedge 300 has a primary
angle, but does not
have a secondary rake angle. In that regard, wedge 300 may be used as damper
264,266 of truck
250 of Figure le, for example, and may provide friction damping with little or
no "stick-slip"
behaviour, but rather friction damping for which the coefficients of static
and dynamic friction are
equal, or only differ by a small (less than about 20%, perhaps less than 10%)
difference. Wedge
300 may be used in truck 250 in conjunction with a bi-directional bearing
adapter of any of the
embodiments described herein. Wedge 300 may also be used in a four cornered
damper
arrangement, as in truck 22, for example, where wedges may be employed that
may lack
secondary angles.
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Figures 7a ¨ 7h
Referring to Figures 7a ¨ 7e, a damper 310 is shown such as may be used in
truck 22, or
any of the other double damper trucks described herein, such as may have
appropriately formed,
mating bolster pockets. Damper 310 is similar to damper 300, but may include
both primary and
secondary angles. Damper 310 may, arbitrarily, be termed a right handed damper
wedge. Figures
7a ¨ 7e are intended to be generic such that it may be understood also to
represent the left handed,
mirror image of a mating damper with which damper 310 would form a matched
pair.
Wedge 310 has a body 312 that may be made by casting or by another suitable
process.
Body 312 may be made of steel or cast iron, and may be substantially hollow.
Body 312 has a
first, substantially planar platen portion 314 having a first face for
placement in a generally
vertical orientation in opposition to a sideframe bearing surface, for
example, a wear plate
mounted on a sideframe column. Platen portion 314 may have a rebate, or
relief, or depression
formed therein to receive a bearing surface wear member, indicated as member
316. Member 316
may be a material having specific friction properties when used in conjunction
with the sideframe
column wear plate material. For example, member 316 may be formed of a brake
lining material,
and the column wear plate may be formed from a high hardness steel. This
material may be
formed as a removable and replaceable pad or block.
Body 312 may include a base portion 318 that may extend rearwardly from and
generally
perpendicularly to, platen portion 314. Base portion 318 may have a relief 320
formed therein in a
manner to form, roughly, the negative impression of an end of a spring coil,
such as may receive a
top end of a coil of a spring of a spring group, such as spring 262. Base
portion 318 may join
platen portion 314 at an intermediate height, such that a lower portion 321 of
platen portion 314
may depend downwardly therebeyond in the manner of a skirt. That skirt portion
may include a
corner, or wrap around portion 322 formed to seat around a portion of the
spring.
Body 312 may also include a diagonal member in the nature of a sloped member
324.
Sloped member 324 may have a first, or lower end extending from the distal end
of base 318 and
running upwardly and forwardly toward a junction with platen portion 314. An
upper region 326
of platen portion 314 may extend upwardly beyond that point ofjunction, such
that damper wedge
310 may have a footprint having a vertical extent somewhat greater than the
vertical extent of
sloped member 324. Sloped member 324 may also have a socket or seat in the
nature of a relief or
rebate 328 formed therein for receiving a sliding face member 330 for
engagement with the bolster
pocket wear plate of the bolster pocket into which wedge 310 may seat. As may
be seen, sloped
member 324 (and face member 330) are inclined at a primary angle a, and a
secondary angle p.
Sliding face member 330 may be an element of chosen, possibly relatively low,
friction properties
(when engaged with the bolster pocket wear plate), such as may include desired
values of
coefficients of static and dynamic friction. In one embodiment the
coefficients of static and
CA 02488960 2004-12-03
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dynamic friction may be substantially equal, may be about 0.2 (+1-20 %, or,
more narrowly +/-
10%), and may be substantially free of stick-slip behaviour.
In the alternative embodiment of Figure 7g, a damper wedge 332 is similar to
damper
wedge 310, but, in addition to pads or inserts for providing modified or
controlled friction
properties on the friction face for engaging the side frame column and on the
face for engaging the
slope of the bolster pocket, damper wedge 332 may have pads or inserts such as
pad 334 on the
side faces of the wedge for engaging the side faces of the bolster pockets. In
this regard, it may be
desirable for pad 334 to have low coefficients of friction, and to tend to be
free of stick slip
behaviour. The friction materials may be cast or bonded in place, and may
include mechanical
interlocking features, such as shown in Figure 6a, or bosses, grooves,
splines, or the like such as
may be used for the same purpose. Similarly, in the alternative embodiment of
Figure 7h, a
damper wedge 336 is provided in which the slope face insert or pad, and the
side wall insert or pad
form a continuous, or monolithic, element, indicated as 338. The material of
the pad or insert
may, again, be cast in place, and may include mechanical interlock features.
Figures 8a 8f
Figures 8a ¨ 8f show an alternate bearing adapter assembly to that of Figure
3a. The
assembly, indicated generally as 350, may differ from that of Figure 3a
insofar as bearing adapter
344 may have an upper surface 346 that may be a load bearing interface surface
of significant
extent, that may be substantially planar and horizontal, such that it may act
as a base upon which
to seat a rocker element, 348. Rocker element 348 may have an upper, or
rocker, surface 352
having a suitable profile, such as a compound curvature having lateral and
longitudinal radii of
curvature, for mating with a corresponding rocker engagement surface of a
pedestal seat liner 354.
As noted above, in the general case each of the two rocking engagement surface
may have both
lateral and longitudinal radii of curvature, such that there are mating
lateral male and female radii,
and mating longitudinal male and female radii. In one embodiment, both the
female radii may be
infinite, such that the pedestal seat may have a planar engagement surface,
and the pedestal seat
liner may be a wear liner, or similar device.
Rocker element 348 may also have a lower surface 356 for seating on, mating
with, and for
transferring loads into, upper surface 346 over a relatively large surface
area, and may have a
suitable through thickness for diffusing vertical loading from the zone of
rolling contact to the
larger area of the land (i.e., surface 346, or a portion thereof) upon which
rocker element 348 sits.
Lower surface 356 may also include a keying, or indexing feature 358 of
suitable shape, and may
include a centering feature 360, both to aid in installation, and to aid in re-
centering rocker
element 348 in the event that it should be tempted to migrate away from the
central position
during operation. Indexing feature 358 may also include an orienting element
for discouraging
misorientation of rocker element 348. Indexing feature 358 may be a cavity 362
of suitable shape
CA 02488960 2004-12-03
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to mate with an opposed button 364 formed on the upper surface 346 of bearing
adapter 344. If
this shape is non-circular, it may tend to admit of only one permissible
orientation. The orienting
element may be defined in the plan form shape of cavity 362 and button 364.
Where the various
radii of curvature of rocker element 348 differ in the lateral and
longitudinal directions, it may be
that two positions 180 degrees out of phase may be acceptable, whereas another
orientation may
not. While an ellipse of differing major and minor axes may serve this
purpose, the shape of
cavity 362 and button 364 may be chosen from a large number of possibilities,
and may have a
cruciform or triangular shape, or may include more than one raised feature in
an asymmetrical
pattern, for example. The centering feature may be defined in the tapered, or
sloped, flanks 368
and 370 of cavity 362 and 364 respectively, in that, once positioned such that
flanks 368 and 370
begin to work against each other, a normal force acting downward on the
interface may tend to
cause the parts to center themselves.
Rocker element 348 has an external periphery 372, defining a footprint.
Resilient members
374 may be taken as being the same as resilient members 156, noted above,
except insofar as
resilient members 374 may have a depending end portion for nesting about the
thrust block of a
jaw of the pedestal, and also a predominantly horizontally extending portion
376 for overlying a
substantial portion of the generally flat or horizontal upper region of
bearing adapter 344. That is,
the outlying regions of surface 346 of bearing adapter 344 may tend to be
generally flat, and may
tend, due to the general thickness of rocker element 348, to be compelled to
stand in a spaced
apart relationship from the opposed, downwardly facing surface of the pedestal
seat, such as may
be, for example, the exposed surface of a wear liner such as item 354, or a
seat such as item 168,
or such other mating part as may be suitable. Portion 376 is of a thickness
suitable for lying in the
gaps so defined, and may tend to be thinner than the mean gap height so as not
to interfere with
operation of the rocker elements. Horizontally extending portion 376 may have
the form of a skirt
such as may include a pair of left and right hand arms or wings 378 and 380
having a profile,
when seen in plan view, for embracing a portion of periphery 372. Resilient
member 374 has a
relief 382 defined in the inwardly facing edge. Where rocker member 348 has
outwardly
extending blisters, or cusps, akin to item 164, relief 382 may function as an
indexing or orientation
feature. A relatively coarse engagement of rocker element 348 may tend to
result in wings 378
and 380 urging rocker element 348 to a generally centered position relative to
bearing adapter 344.
This coarse centering may tend to cause cavity 362 to pick up on button 364,
such that rocker
member 348 is then urged to the desired centered position by a fine centering
feature, namely the
chamfered flanks 368, 370. The root of portion 376 may be relieved by a radius
384 adjacent the
juncture of surface 346 with the end wall 386 of bearing adapter 348 to
discourage chaffing of
resilient member 372, 374 at that location.
Without the addition of a multiplicity of drawings, it may be noted that
rocker element 348
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could, alternatively, be inverted so as to seat in an accommodation formed in
the pedestal roof,
with a land facing toward the roof, and a rocking surface facing toward a
mating bearing adapter,
be it adapter 44 or some other.
Figures 9a and 9b
Figure 9a shows an alternative arrangement to that of Figure 3a or Figure 8a.
In the
wheelset to sideframe interface assembly of Figure 9a, indicated generally as
400, bearing adapter
404 may be substantially similar to bearing adapter 344, and may have an upper
surface 406 and a
rocker element 408 that interact in the same manner as rocker element 348
interacts with surface
346. (Or, in the inverted case, the rocker element may be seated in the
pedestal roof, and the
bearing adapter may have a mating upwardly facing rocker surface). The rocker
element may
interact with a pedestal seat fitting 410 such as may be a wear liner seated
in the pedestal roof.
Rocker element 408 and the body of bearing adapter 404 may have mating
indexing features as
described in the context of Figures 8a to 8e.
Rather than two resilient members, such as items 374, however, assembly 400
employs a
single resilient member 412, such as may be a monolithic cast material, be it
polyurethane or a
suitable rubber or rubberlike material such as may be used, for example, in
making an LC pad or a
Pennsy pad. An LC pad is an elastomeric bearing adapter pad available from
Lord Corporation of
Erie Pennsylvania. An example of an LC pad may be identified as Standard Car
Truck Part Number
SCT 5578. In this instance, resilient member 412 has first and second end
portions 414, 416 for
interposition between the thrust lugs of the jaws of the pedestal and the ends
418 and 420 of the
bearing adapter. End portions 414, 416 may tend to be a bit undersize so that,
once the roof liner
is in place, they may slide vertically into place on the thrust lugs, possibly
in a modest interference
fit. The bearing adapter may slide into place thereafter, and again, may do so
in a slight
interference fit, carrying the rocker element 408 with it into place.
Resilient member 412 may also have a central or medial portion 422 extending
between
end portions 414, 416. Medial portion 422 may extend generally horizontally
inward to overlie
substantial portions of the upper surface bearing adapter 404. Resilient
member 412 may have an
accommodation 424 formed therein, be it in the nature of an aperture, or
through hole, having a
periphery of suitable extent to admit rocker element 408, and so to permit
rocker element 408 to
extend at least partially through member 412 to engage the mating rocking
element of the pedestal
seat. It may be that the periphery of accommodation 422 is matched to the
shape of the footprint
of rocker element 408 in the manner described in the context of Figures 8a to
Se to facilitate
installation and to facilitate location of rocker element 408 on bearing
adapter 404. In one
embodiment resilient member 412 may be formed in the manner of a Pennsy Pad
with a suitable
central aperture formed therein.
Figure 9b shows a Pennsy pad installation. In this installation, a bearing
adapter is
CA 02488960 2012-08-29
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indicated as 430, and an elastomeric member, such as may be a Pennsy pad, is
indicated as 432.
On installation, member 432 seats between the pedestal roof and the bearing
adapter. The term
"Pennsy pad", or "Pennsy Adapter Plus", refers to a kind of elastomeric pad
developed by Pennsy
Corporation of Westchester Pa. One example of such a pad is illustrated in US
Patent 5,562,045
of Rudibaugh et al., issued October 6, 1996. Figure 9b may include a pad 432
and bearing
adapter of 430 the same, or similar, nature to those shown and described in
the 5,562,045 patent.
The Pennsy pad may tend to permit a measure of passive steering. The Pennsy
pad installation
of Figure 9b can be installed in the sideframe of Figure la, in combination
with a four cornered
damper arrangement, as indicated in Figures la ¨ id. In this embodiment the
truck may be a
Barber S2HD truck, modified to carry a damper arrangement, such as a four-
cornered damper
arrangement, such as may have an enhanced restorative tendency in the face of
non-square
deformation of the truck, having dampers that may include friction surfaces as
described herein.
Figures 10a ¨ 10e
Figure 10a shows a further alternate embodiment of wheelset to sideframe
interface
assembly to that of Figure 3a or Figure 8a. In this instance, bearing adapter
444 may have an
upper rocker surface of any of the configurations discussed above, or may have
a rocker element
in the manner of bearing adapter 344.
The underside of bearing adapter 444 may have not only a circumferentially
extending
medial groove, channel or rebate 446, having an apex lying on the transverse
plane of symmetry
of bearing adapter 444, but also a laterally extending underside rebate 448
such as may tend to lie
parallel to the underlying longitudinal axis of the wheelset shaft and bearing
centreline (i.e., the
axial direction) such that the underside of bearing adapter 444 has four
corner lands or pads 450
arranged in an array for seating on the casing of the bearing. In this
instance, each of the pads, or
lands, may be formed on a curved surface having a radius conforming to a body
of revolution such
as the outer shell of the bearing. Rebate 448 may tend to lie along the apex
of the arch of the
underside ofbearing adapter 444, with the intersection of rebates 446 and 448.
Rebate 448 may
be relatively shallow, and may be gently radiused into the surrounding bearing
adapter body. The
body of bearing adapter 444 is more or less symmetrical about both its
longitudinal central vertical
plane (i.e., on installation, that plane lying vertical and parallel to, if
not coincident with, the
longitudinal vertical central plane of the sideframe), and also about its
transverse central plane
(i.e., on installation, that plane extending vertically radially from the
center line of the axis of
rotation of the bearing and of the wheelset shaft). It may be noted that axial
rebate 448 may tend
to lie at the section of minimum cross-sectional area of bearing adapter 444.
Rebates 446 and 448
may tend to divide, and spread, the vertical load carried through the rocker
element over a larger
area of the casing of the bearing, and hence more evenly to distribute the
load into the rollers of
CA 02488960 2004-12-03
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the bearing than might otherwise be the case. It is thought that this may tend
to encourage longer
bearing life.
In the general case, bearing adapter 444 may have an upper surface having a
crown to
permit self-steering, or may be formed to accommodate a self-steering
apparatus such as an
elastomeric pad, such as a Pennsy Pad or other pad. In the event that a rocker
surface is
employed, whether by way of a separable insert, or a disc, or is integrally
formed in the body of
the bearing adapter, the location of the contact of the rocker in the resting
position may tend to lie
directly above the center of the bearing adapter, and hence above the
intersection of the axial and
circumferential rebates in the underside of bearing adapter 444.
Figures 1 la ¨ 1 lf
Figures ha ¨ llf show views of a bearing adapter 452, a pedestal seat insert
454 and
elastomeric bumper pad members 456, as an assembly for insertion between
bearing 46 and
sideframe 26. Bearing adapter 452 and pad members 456 are generally similar to
bearing adapter
171 and members 156, respectively. They differ, however, insofar as bearing
adapter 452 has
thrust block standoff elements 460, 462 located at either end thereof, and the
lower corners of
bumpers 456 have been truncated accordingly. It may be that for a certain
range of deflection, an
elastomeric response is desired, and may be sufficient to accommodate a high
percentage of in-
service performance. However, excursion beyond that range of deflection might
tend to cause
damage, or reduction in life, to pad members 456. Standoff elements 460, 462
may act as
limiting stops to bound that range of motion. Standoff elements 460, 462 may
have the form of
shelves, or abutments, or stops 466,468 mounted to, and standing proud of, the
laterally inwardly
facing faces of the corner abutment portions 470, 472 of bearing adapter 452
more generally. As
installed, stops 466,468 underlie toes 474, 476 of members 456. As may be
noted, toes 474, 476
have a truncated appearance as compared to the toes of member 356 in order to
stand clear of
stops 466, 468 on installation. In the at rest, centered condition, stops 466,
468 may tend to stand
clear of the pedestal jaw thrust blocks by some gap distance. When the lateral
deflection of the
elastomer in member 456 reaches the gap distance, the thrust lug may tend to
bottom against stop
466 or 468, as the case may be. The sheltering width of stops 466,468 (i.e.,
the distance by which
they stand proud of the inner face of corner abutment portions 470, 472) may
tend to provide a
reserve compression zone for wings 475, 477 and may thereby tend to prevent
them from being
unduly squeezed or pinched. Pedestal seat insert 454 may be generally similar
to liner 354, but
may include radiused bulges 480, 482, and a thicker central portion 484.
Bearing adapter 452 may
include a central bi-directional rocker portion 486 for mating rocking
engagement with the
downwardly facing rocking surface of central portion 484. The mating surfaces
may conform to
any of the combinations of bi-directional rocking radii discussed herein.
Rocker portion 486 may
be trimmed laterally as at longitudinally running side shoulders 488, 490 to
accommodate bulges
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480, 482.
Bearing adapter 452 may also have different underside grooving, 492 in the
nature of a
pair of laterally extending tapered lobate depressions, cavities, or reliefs
494, 496 separated by a
central bridge region 498 having a deeper section and flanks that taper into
reliefs 494, 496.
Reliefs 494, 496 may have a major axis that runs laterally with respect to the
bearing adapter
itself, but, as installed, runs axially with respect to the axis of rotation
of the underlying bearing.
The absence of material at reliefs 494, 496 may tend to leave a generally H-
shaped footprint on
the circumferential surface 500 that seats upon the outside of bearing 46, in
which the two side
regions, or legs, of the H form lands or pads 502,504 joined by a relatively
narrow waist, namely
bridge region 498. To the extent that the undersurface of the lower portion of
bearing adapter 452
conforms to an arcuate profile, such as may accommodate the bearing casing,
reliefs 494,496 may
tend to run, or extend, predominantly along the apex of the profile, between
the pads, or lands, that
lie to either side. This configuration may tend to spread the rocker rolling
contact point load into
pads 502, 504 and thence into bearing 46. Bearing life may be a function of
peak load in the
rollers. By leaving a space between the underside of the bearing adapter and
the top center of the
bearing casing over the bearing races, reliefs 494,496 may tend to prevent the
vertical load being
passed in a concentrated manner predominantly into the top rollers in the
bearing. Instead, it may
be advantageous to spread the load between several rollers in each race. This
may tend to be
encouraged by employing spaced apart pads or lands, such as pads 502, 504,
that seat upon the
bearing casing. Central bridge region 498 may seat above a section of the
bearing casing under
which there is no race, rather than directly over one of the races. Bridge
region 498 may act as a
central circumferential ligature, or tension member, intermediate bearing
adapter end arches 506,
508 such as may tend to discourage splaying or separation of pads 502, 504
away from each other
as vertical load is applied.
Figures 12a ¨ 12d
Figures 12a to 12d show an alternate assembly to that of Figure 11a, indicated
generally as
510 for seating in a sideframe 512. Bearing 46 and bearing adapter 452 may be
as before.
Assembly 510 may include an upper rocker fitting identified as pedestal seat
member 514, and
resilient members 516. Sideframe 512 may be such that the upper rocker
fitting, namely pedestal
seat member 514 may have a greater through thickness, ts, than otherwise. This
thickness, ts may
be greater than 10 % of the magnitude of the width Ws of the pedestal seat
member, and may be
about 20 (+1-5) % of the width. In one embodiment the thickness may be roughly
the same as the
thickness of and 'LC pad' such as may be obtained from Lord Corporation. Such
thickness may
be greater than 7/16", and such thickness may be 1 inch (+1- 1/8"). Pedestal
seat member 514 may
tend to have a greater thickness for enhancing the spreading of the rocker
contact load into
sideframe 512. It may also be used as part of a retro-fit installation in
sideframes such as may
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formerly have been made to accommodate LC pads.
Pedestal seat member 514 may have a generally planar body 518 having upturned
lateral
margins 520 for bracketing, and seating about, the lower edges of the
sideframe pedestal roof
member 522. The major portion of the upper surface of body 518 may tend to
mate in planar
contact with the downwardly facing surface of roof member 522. Seat member 514
may have
protruding end potions 524 that extend longitudinally from the main, planar
portion of body 518.
End portions 524 may include a deeper nose section 526, that may stand
downwardly proud of two
wings 528, 530. The depth of nose section 526 may correspond to the general
through thickness
depth of member 514. The lower, downwardly facing surface 532 of member 518
(as installed)
may be formed to mate with the upper surface of the bearing adapter, such that
a bi-directional
rocking interface is achieved, with a combination of male and female rocking
radii as described
herein. In one embodiment the female rocking surface may be planar.
Resilient members 516 may be formed to engage protruding portions 524. That
is,
resilient member 516 may have the generally channel shaped for of resilient
member 156, having
a lateral web 534 standing between a pair of wings 536, 538. However, in this
embodiment, web
534 may extend, when installed, to a level below the level of stops 466, 468,
and the respective
base faces 540, 542 of wings 536, 538 are positioned to sit above stops 466,
468. A superior
lateral wall, or bulge, 544 surmounts the upper margin of web 534, and extends
longitudinally,
such as may permit it to overhang the top of the sideframe jaw thrust lug 546.
The upper surface
of bulge 544 may be trimmed, or flattened to accommodate nose section 526. The
upper
extremities of wings 536, 538 terminate in knobs, or prongs, or horns 548, 550
that stand
upwardly proud of the flattened surface 552 of bulge 544. As installed, the
upper ends of horns
548, 550 underlie the downwardly facing surfaces of wings 536, 538.
In the event that an installer might attempt to install bearing adapter 452 in
sideframe 512
without first placing pedestal seat member 512 in position, the height of
horns 548, 550 is
sufficient to prevent the rocker surface of bearing adapter 452 from engaging
sideframe roof
member 522. That is, the height of the highest portion of the crown of the
rocker surface 552 of
the bearing adapter is less than the height of the ends of horns 548, 550 when
horns 548, 550 are
in contact with stops 466, 468. However, when pedestal seat member 512 is
correctly in place,
nose section 526 is located between wings 536, 538, and wings 536,538 are
captured above horns
548, 550. In this way, resilient members 514, and in particular horns 548,
550, act as installation
error detection elements, or damage prevention elements.
The steps of installation may include the step of removing an existing bearing
adapter,
removing an existing elastomeric pad, such as an LC pad, installing pedestal
seat fitting 514 in
engagement with roof 522; seating of resilient members 514 above each of
thrust lugs 546; and
sliding bearing adapter 452 between resilient pad members 514. Resilient pad
members 514 then
_.
_______________________________________________________________________________
___________
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serve to locate other elements on assembly, to retain those elements in
service, and to provide a
centering bias to the mating rocker elements, as discussed above.
Figures 13a ¨ 13g
Figures 13a to 13g show and alternate bearing adapter 144 and pedestal seat
146 pair.
Bearing adapter 144 is substantially the same as bearing adapter 44, except
insofar as bearing adapter
44 has a fully curved top surface 142, whereas bearing adapter 144 has an
upper surface that has a flat
central portion 148 between somewhat elevated side portions 149. The male
bearing surface portion
147 is located centrally on flat central portion 148, and extends upwardly
therefrom. As with bearing
adapter 44, bearing adapter 144 has first and second radii r1 and r2, formed
in the longitudinal and
transverse directions respectively, such that the upwardly protruding surface
so formed is a toroidal
surface. Pedestal seat 146 is substantially similar to pedestal seat fitting
38. Pedestal seat 146 has a
body having an upper surface 145 that seats in planar abutment against the
downwardly facing
surface of pedestal roof 120, and upwardly extending tangs 124 that engage
lugs 122 as before.
While in the general sense, the female engagement fitting portion, namely the
hollow
depression formed in the lower face of seat 146, is formed on longitudinal and
lateral radii R1 and R29
as above, when these two radii are equal a spherical surface 143 is formed,
giving the circular plan
view of Figure 13a. Figures 13f and 13g serve to illustrate that the male and
female surfaces may be
inverted, such that the female engagement surface 560 is formed on bearing
adapter 562, and the
male engagement surface 564 on seat 566.
Figures 14a ¨ 14e
Figures 14a ¨ 14e show enlarged views of bearing adapter 44 and pedestal seat
fitting 38.
The compound curve of upwardly facing surface 142 runs fully to terminate at
the end faces 134, and
the side faces 570 of bearing adapter 44. The side faces show the circularly
downwardly arched
lower walls margins 572 of side faces 570 that seat about bearings 46. In all
other respects, for the
purposes of this description, bearing adapter 44 can be taken as being the
same as bearing adapter
144.
Figures 15a - 15c
Figures 15a ¨ 15c, show a conceptually similar bearing adapter and pedestal
seat combination
to that of Figures 13a to 13g, but rather than having the interface portions
standing proud of the
remainder of the bearing adapter, the male portion 574 is sunken into the top
of the bearing adapter,
and the surrounding surface 576 is raised up. The mating female portion 578
while retaining its
hollowed out shape, stands proud of the surrounding structure of the seat to
provide a corresponding
mating surface. The longitudinally extending phantom lines indicate drain
ports to discourage the
collection of water.
Figures 16a - 16e
Both female radii R1 and R2 need not be on the same fitting, and both male
radii r1 and r2
CA 02488960 2004-12-03
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need not be on the same fitting. In the saddle shaped fittings of Figures lba
to 16e, a bearing adapter
580 is of substantially the same construction as bearing adapters 44 and 144,
except insofar as bearing
adapter 580 has an upper surface 592 that has a male fitting in the nature of
a longitudinally extending
crown 582 with a laterally extending axis of rotation, for which the radius of
curvature is r1, and a
female fitting in the nature of a longitudinally extending trough 584 having a
lateral radius of
curvature R2. Similarly, pedestal fitting 586 mounted in roof 120 has a
generally downwardly facing
surface 594 that has a transversely extending trough 588 having a
longitudinally oriented radius of
curvature 121, for engagement with n of crown 582, and a longitudinally
running, downwardly
protruding crown 590 having a transverse radius of curvature r2 for engagement
with R2 of trough
584. In Figures 16f and 16g the saddle surfaces are inverted such that whereas
bearing adapter 580
has ri and R2, bearing adapter 596 has r2 and RI. Similarly, whereas pedestal
fitting 586 has r2 and
RI, pedestal fitting 598 has n and R2. In either case, the smallest of R1 and
R2 may be larger than, or
equal to, the largest of ri and r2, and the mating opposed saddle surfaces,
over the desired range of
motion, may tend to be torsionally decoupled as in bearing adapters 44 and
144.
Figures 17a ¨ 17d
It may be desired that the vertical forces transmitted from the pedestal roof
into the bearing
adapter be passed through line contact, rather than the bi-directional rolling
or rocking point contact.
A pedestal seat to bearing adapter interface assembly having line contact
rocker interfaces is
represented by Figures 17a to 17d. A bearing adapter 600 has a hollowed out
transverse cylindrical
upper surface 602, acting as a female engagement fitting portion formed on
radius R1. Surface 602
may be a round cylindrical section, or it may be a parabolic, or other
cylindrical section.
The corresponding pedestal seat fitting 604 may have a longitudinally
extending female
fitting, or trough, 606 having a cylindrical surface 608 formed on radius n .
Again, fitting 604 is
cylindrical, and may be a round cylindrical section although, alternatively,
it could be parabolic,
elliptic, or some other shape for producing a rocking motion. Trapped between
bearing adapter 600
and pedestal seat fitting 604 is a rocker member 610. Rocker member 610 has a
first, or lower
portion 612 having a protruding male cylindrical rocker surface 614 formed on
a radius n for line
contact engagement of surface 602 of bearing adapter 600 formed on radius Rli
n being smaller than
111, and thus permitting longitudinal rocking to obtain passive self steering.
As above, the resistance
to rocking, and hence to self steering, may tend to be proportional to the
weight on the rocker and
hence may give proportional self steering when the car is either empty or
loaded. Lower portion 612
also has an upper relief 616 that may be machined to a high level of flatness.
Lower portion 612 also
has a centrally located, integrally formed upwardly extending cylindrical stub
618 that stands
perpendicularly proud of surface 616. A bushing 620, which may be a press fit
bushing, mounts on
stub 618.
Rocker member 600 also has an upper portion 622 that has a second protruding
male
CA 02488960 2004-12-03
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cylindrical rocker surface 624 formed on a radius r2 for line contact
engagement with the cylindrical
surface 608 of trough 606, formed on radius R2, thus permitting lateral
rocking of sideframe 26.
Upper portion 622 may have a lower relief 626 for placement in opposition to
relief 616. Upper
portion 622 has a centrally located blind bore 628 of a size for tight fitting
engagement of bushing
620, such that a close tolerance, pivoting connection is obtained that is
largely compliant to pivotal
motion about the vertical, or z, axis of upper portion 622 with respect to
lower portion 612. That is to
say, the resistance to torsional motion about the z-axis is very small, and
can be taken as zero for the
purposes of analysis. To aid in this, bearing 630 may be installed about stub
618 and bushing 620
and is placed between opposed surfaces 606 and 616 to encourage relative
rotational motion
therebetween.
In this embodiment, stub 618 could be formed in upper portion 622, and bore
618 formed in
lower portion 612, or, alternatively, bores 628 could be formed in both upper
portion 612 and lower
portion 622, and a freely floating stub 618 and bushing 620 could be captured
between them. It may
be noted that the angular displacement about the z axis of upper portions 622
relative to lower portion
612 may be quite small ¨ of the order of 1 degree, and may tend not to be even
that large overly
frequently.
Bearing adapter 600 may have longitudinally extending raised lateral abutment
side walls 632
to discourage lateral migration, or escape of lower portion 612. Lower portion
612 may have non-
galling, relatively low co-efficient of friction side wear shim stock members
634 trapped between the
end faces of lower portion 612 and side walls 632. Bearing adapter 600 may
also have a drain hole
formed therein, possibly centrally, or placed at an angle. Similarly, pedestal
seat fitting 604 may have
laterally extending depending end abutment walls 636 to discourage
longitudinal migration, or
escape, of upper portion 622. In a like manner to shim stock members 634, non-
galling, relatively
low co-efficient of friction end wear shim stock members 638 may be mounted
between the end faces
of upper portion 622 and end abutment walls 636.
In an alternative to the foregoing embodiment, the longitudinal cylindrical
trough could be
formed on the bearing adapter, and the lateral cylindrical trough could be
formed in the pedestal seat,
with corresponding changes in the entrapped rocker element. Further, it is not
necessary that the male
cylindrical portions be part of the entrapped rocker element. Rather, one of
those male portions could
be on the bearing adapter, and one of those male portions could be on the
pedestal seat, with the
corresponding female portions being formed on the entrapped rocker element. In
the further
alternative, the rocker element could include one male element, and one female
element, having the
male element formed on 1.1 (or r2) being located on the bearing adapter, and
the female element
formed on R1 (or R2) being on the underside of the entrapped rocker element,
and the male element
formed on r2 (or ri) being formed on the upper surface of the entrapped rocker
element, and the
respective mating female element formed on radius R2 (or R1) being formed on
the lower face of the
CA 02488960 2004-12-03
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pedestal seat. In the still further alternative, the rocker element could
include one male element, and
one female element, having the male element formed on r1 (or r2) being located
on the pedestal seat,
and the female element formed on R1 (or R2) being on the upper surface of the
entrapped rocker
element, and the male element formed on r2 (or ri) being formed on the lower
surface of the
entrapped rocker element, and the respective mating female element formed on
radius R2 (or R1)
being formed on the upper face of the bearing adapter. There are, in this
regard, at least eight
combinations as represented in Figure 17e by assemblies 601, 603, 605, 607,
611, 613, 615, and 617.
The embodiment of Figures 17a ¨ 17d may tend to yield line contact at the
force transfer
interfaces, and yet rock in both the longitudinal and lateral directions, with
compliance to torsion
about the vertical axis. That is, the bearing adapter to pedestal seat
interface assembly may tend to
permit rotation about the longitudinal axis to give lateral rocking motion of
the side frame; rotation
about a transverse axis to give longitudinal rocking motion; and compliance to
torsion about the
vertical axis. It may tend to discourage lateral translation, and may tend to
retain high stiffness in the
vertical direction.
Figures 18a and 18b
The embodiment of Figures 18a and 18b is substantially similar to the
embodiment of Figures
17a to 17d. However, rather than employing a pivot connection such as the
bore, stub, bushing and
bearing of Figures 17a ¨ 17d, a rocker element 644 is captured between bearing
adapter 600 and
pedestal seat 604. Rocker element 644 has a torsional compliance element made
of a resilient
material, identified as elastomeric member 646 bonded between the opposed
faces of the upper 647
and lower 645 portions of rocker element 644. Although Figures 18a and 18b
show the laterally
extending trough in bearing adapter 600, and the longitudinal trough in
pedestal seat 604, the same
permutations of Figure 7e may be made. In general, while the torsional element
may be between the
two cylindrical elements in a manner tending torsionally to decouple them, it
may be that the
elastomeric pad need not necessarily be installed between the two cylindrical
members. For example,
the rocker element 644 may be solid, and an elastomeric element may be
installed beneath the top
surface of bearing adapter 600, or above the pedestal seat element, such that
a torsionally compliant
element is placed in series with the two rockers.
The same general commentary may be made with regard to the pivotal connection
suggested
above in connection with the example of Figures 17a to 17d. That is, the top
of the bearing adapter
could be pivotally mounted to the body of the bearing adapter more generally,
or the pedestal seat
could be pivotally mounted to the pedestal roof, such that a torsionally
compliant element would be in
series with the two rockers. However, as noted above, the torsionally
compliant element may be
between the two rockers, such that they may tend to be torsionally de-coupled
from each other. In
general, with regard to the embodiments of Figures 17a ¨ 17d, and 18a ¨ 18b,
provided that the radii
employed yield a physically appropriate combination tending toward a local
stable minimum energy
CA 02488960 2004-12-03
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state, the male portion of the bearing adapter to pedestal seat interface
(with the smaller radius of
curvature) may be on either the bearing adapter or on the pedestal seat, and
the mating female portion
(with the larger radius of curvature) may be on the other part, whichever it
may be. In that light,
although a particular depiction may show a male portion on a bearing adapter,
and a female fitting on
the pedestal seat, these features may, in general, be reversed.
Figures 19a to 19c, 20a to 20c, and 21a to 21g
Figures 19a to 19c show the combination of a bearing adapter 650 with an
elastomeric
bearing adapter pad 652 and a rocker 654 and pedestal seat 656 to permit
lateral rocking of the
sideframe. Bearing adapter 650, shown in three additional views in Figures 20a
¨ 20c is substantially
similar to bearing adapter 44 (or 144) to the extent of its geometric features
for engaging a bearing,
but differs therefrom in having a more or less conventional upper surface.
Upper surface 658 may be
flat, or may have a large (roughly 60") radius crown 660, such as might have
been used for engaging
a planar pedestal seat surface. Crown 660 is split into two fore-and-aft
portions, with a laterally
extending central flat portion between them. Abreast of the central flat
portion, bearing adapter 650
has a pair of laterally proud, outwardly facing lateral lands, 662 and 664,
and, amidst those lands,
lateral lugs 666 that extend further still proud beyond lands 662 and 664.
Bearing adapter pad 652 may be a commercially available assembly such as may
be
manufactured by Lord Corporation of Erie Pennsylvania, or such as may be
identified as Standard
Car Truck Part Number SCT 5844. Bearing adapter pad 652 has a bearing adapter
engagement
member in the nature of a lower plate 668 whose bottom surface 670 is relieved
to seat over crown
660 in non-rocking engagement. Lateral and longitudinal translation of bearing
adapter pad 652 is
inhibited by an array of downwardly bent securement locating lugs, or fingers,
or claws, in the nature
of indexing members or tangs 672, two per side in pairs located to reach
downwardly and bracket
lugs 666 in close fitting engagement. The bracketing condition with respect to
lugs 666 inhibits
longitudinal motion between bearing adapter pad 652 and bearing adapter 650.
The laterally inside
faces of tangs 672 closely oppose the laterally outwardly facing surfaces of
lands 662 and 664,
tending thereby to inhibit lateral relative motion of bearing adapter pad 652
relative to bearing
adapter 650. The vertical, lateral, and longitudinal position relative to
bearing adapter 650 can be
taken as fixed.
Bearing adapter pad 652 also has an upper plate, 674, that, in the case of a
retro-fit installation
of rocker 654 and seat 656, may have been used as a pedestal seat engagement
member. In any case,
upper plate 674 has the general shape of a longitudinally extending channel
member, with a central,
or back, portion, 676 and upwardly extending left and right hand leg portions
678,680 adjoining the
lateral margins of back portion 676. Leg portions 678 may have a size and
shape such as might have
been suitable for mounting directly to the sideframe pedestal.
Between lower plate 668 and upper plate 674, bearing adapter pad 652 has a
bonded resilient
CA 02488960 2004-12-03
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sandwich 680 that may include a first resilient layer, indicated as lower
elastomeric layer 682
mounted directly to the upper surface of lower plate 668, an intermediate
stiffener shear plate 684
bonded or molded to the upper surface of layer 682, and an upper resilient
layer, indicated as upper
elastomeric layer 686 bonded atop plate 684. The upper surface of layer 686
may be bonded or
molded to the lower surface of upper plate 674. Given that the resilient
layers may be quite thin as
compared to their length and breadth, the resultant sandwich may tend to have
comparatively high
vertical stiffness, comparatively high resistance to torsion about the
longitudinal (x) and lateral (y)
axes, comparatively low resistance to torsion about the vertical (z) axis
(given the small angular
displacements in any case), and non-trivial, roughly equal resistance to shear
in the x or y directions
that may be in the range of 20,000 to 40,000 lbs per inch, or more narrowly,
about 30,000 lbs per inch
for small deflections. Bearing adapter pad 652 may tend to permit a measure of
self steering to be
obtained when the elastomeric elements are subjected to longitudinal shear
forces.
Rocker 654 (seen in additional views 21e, 21f and 21g) has a body of
substantially constant
cross-section, having a lower surface 690 formed to sit in substantially flat,
non-rocking engagement
upon the upper surface of plate 674 of bearing adapter pad 652, and an upper
surface 692 formed to
define a male rocker surface. Upper surface 692 may have a continuously radius
central portion 694
lying between adjacent tangential portions 696 lying at a constant slope
angle. In one embodiment,
the central portion may describe 4 ¨ 6 degrees of arc to either side of a
central position, and may, in
one embodiment have about 4-1/2 to 5 degrees. In the terminology used above,
this radius is "r2", the
male radius of a lateral rocker for permitting lateral swinging motion of side
frame 26. Where a
bearing adapter with a crown radius is mounted under the resilient bearing
adapter pad, the radius of
rocker 654 is less than the radius of the crown, perhaps less than half the
crown radius, and possibly
being less than 1/3 of the crown radius. It may be formed on a radius of
between 5 and 20 inches, or,
more narrowly, on a radius of between 8 and 15 inches. Surface 692 could also
be formed on a
parabolic profile, an elliptic or hyperbolic profile, or some other profile to
yield lateral rocking.
Pedestal seat 656 (seen in Figures 21a to 21d) has a body having a major
portion 700 that is
substantially rectangular in plan view. When viewed from one end in the
longitudinal direction,
pedestal seat 656 has a generally channel shaped cross-section, in which major
portion 700 forms the
back 702 and two longitudinally running legs 704,706 extend upwardly and
laterally outwardly from
the lateral margins of major portion 700. Legs 704 and 706 have an inner, or
proximal portion 708
that extends upwardly and outwardly at an angle from the lateral margins of
main portion 700, and an
outer, or distal portion, or toe 710 that extends from the end of proximal
portion 708 in a substantially
vertical direction. The breadth between the opposed fmgers of the channel
section (i.e., between
opposed toes 710) corresponds to the width of the sidefiume pedestal roof 712,
as shown in the cross-
section of Figure 19b, with which legs 704 and 706 sit in close fitting,
bracketing engagement. Legs
704 and 706 have longitudinally centrally located cut-outs, reliefs, rebates,
or indexing features,
CA 02488960 2004-12-03
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identified as notches 714. Notches 714 seat in close fitting engagement about
T-shaped lugs 716
(Figure 19b) that are welded to the sideframe on either side of the pedestal
roof. This engagement
establishes the lateral and longitudinal position of pedestal seat 656 with
respect to sideframe 26.
Pedestal seat 656 also has four laterally projecting corner lugs, or abutment
fittings 718,
whose longitudinally inwardly facing surfaces oppose the laterally extending
end-face surfaces of the
upturned legs 678 of upper plate 674 of bearing adapter pad 652. That is, the
corner abutment fittings
718 on either lateral side of pedestal seat 656 bracket the ends of the
upturned legs 678 of adapter
pad 652 in close fitting engagement. This relationship fixes the longitudinal
position of pedestal seat
656 relative to the upper plate of bearing adapter pad 652.
Major portion 700 of pedestal seat 656 has a downwardly facing surface 700
that is hollowed
out to form a depression defining a female rocking engagement surface 702.
This surface is formed
on a female radius (identified as R2 in concordance with terminology used
herein above) that is quite
substantially larger than the radius of central portion 694 (Figure 21i) of
rocker 654, such that rocker
654 and pedestal seat 656 meet in rolling line contact engagement and permit
sideframe 26 to swing
laterally in a lateral rocking relationship on rocker 654. The arcuate profile
of female rocking
engagement surface 702 may be such as to encourage lateral self centering of
rocker 654, and may
have a radius of curvature that varies from a central region to adjacent
regions, which may be
tangential planar regions. Where pedestal seat 656 and rocker 654 are provided
by way of retro-fit
installation above an adapter having a crown radius, the radius of curvature
of the pedestal seat may
tend to be less than or equal to the crown radius. The central radius of
curvature R2 of surface 702, or
the radius of curvature generally if constant, may be in the range of 6 to 60
inches, is preferably
greater than 10 inches and less than 40 inches. It may be between 11/10 to 4
times as large as the
rocker radius of curvature r2. As noted elsewhere, the pedestal seat need not
have the female rocker
surface, and the rocker need not have the male rocker surface, but rather,
these surfaces could be
reversed, so that the male surface is on the pedestal seat, and the female
surface is on the rocker.
Particularly in the context of a retro-fit installation, there may be
relatively little clearance between
the upturned legs 678 of upper plate 674 and legs 704, 706 of pedestal seat
656. This distance is
shown in Figure 19b as gap 'G', which is preferably sufficient allowance for
rocking motion between
the parts that rocking motion is bounded by the spacing of the truck bolster
gibs 106, 108.
By providing the combination of a lateral rocker and a shear pad, the
resultant assembly may
provide a generally increased softness in the lateral direction, while
permitting a measure of self
steering. The example of Figure 19a may be provided as an original
installation, or may be provided
as a retrofit installation. In the case of a retrofit installation, rocker 654
and pedestal seat 656 may be
installed between an existing elastomeric pad and an existing pedestal seat,
or may be installed in
addition to a replacement elastomeric pad of lesser through- thickness, such
that the overall height of
the bearing adapter to pedestal seat interface may remain roughly the same as
it was before the
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retrofit.
Figures 19e and 19f represent alternate embodiments of combinations of
elastomeric pads and
rockers. While the embodiment of Figure 19a showed an elastomeric sandwich
that had roughly
equivalent response to shear in the lateral and longitudinal directions, this
need not be the general
case. For example, in the embodiments of Figures 19e and 19f, elastomeric
bearing adapter pad
assemblies 720 and 731 have respective resilient elastomeric laminates
sandwiches, indicated
generally as 722 and 723 in which the stiffeners 726,727 have longitudinally
extending corrugations,
or waves. In the longitudinal direction, the sandwich may tend to react in
nearly pure shear, as before
in the example of Figure 19a. However, deflection in the lateral direction now
requires not only a
shear component, but also a component normal to the elastomeric elements, in
compressive or tensile
stress, rather than, and in addition to, shear. This may tend to give a
stiffer lateral response, and
hence an anisotropic response. An anisotropic shear pad arrangement of this
nature might have been
used in the embodiment of Figure 19a, and a planar arrangement, as in the
embodiment of Figure 19a
could be used in either of the embodiments of Figures 19e, and 19f.
Considering Figure 19e, both
base plate 728 and upper plate 730 have a wavy contour corresponding to the
wavy contour of
sandwich 722 generally. Rocker 732 has a lower surface of corresponding
profile. Otherwise, this
embodiment is substantially the same as the embodiment of Figure 19a.
Considering Figure 19f, an elastomeric bearing adapter pad assembly 721 has a
base plate
734 having a lower surface for seating in non-rocking relationship on a
bearing adapter, in the same
manner as bearing adapter pad assembly 652 sits upon bearing adapter 650. The
upper surface 735 of
base plate 734 has a corrugated or wavy contour, the corrugations running
lengthwise, as discussed
above. An elastomeric laminate of a first resilient layer 736, an internal
stiffener plate 737, and a
second resilient layer 738 are located between base plate 734 and a
correspondingly wavy
undersurface of upper plate 740. Rather than being a flat plate upon which a
further rocker plate is
mounted, upper plate 740 has an upper surface 742 having an integrally formed
rocker contour
corresponding to that of the upper surface of rocker 654. Pedestal seat 744
then mounts directly to,
and in lateral rocking relationship with upper plate 740, without need for a
separate rocker part. The
combination of bearing adapter pad 721 and pedestal seat 742 may have
interconnecting abutments
747 to prevent longitudinal migration of rocker surface 742 relative to the
contoured downwardly
facing surface 748 of pedestal seat 744.
Figures 22a to 22c, 23a and 23b
Rather than employ a bearing adapter that is separate from the bearing,
Figures 22a to 22c
show a bearing 750 mounted on one of the end of an axle 752. Bearing 750 has
an integrally formed
arcuate rolling contact surface 754 for mating rolling point contact with a
mating rolling contact
surface 756 of a pedestal seat fitting 758. The general geometry of the
rolling relationship is as
described below in terms of the possible relationships of n, R1 and L, and, as
noted above, the male
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and female rolling contact surfaces can be reversed, such that the male
surface is on the pedestal seat,
and the female surface is on the bearing, or further still, in the case of a
compound curvature, the
surfaces made be saddle shaped, as described above. The bearing illustrations
of Figures 22b and
23h are based on the bearing cross-section illustration shown on page 812 of
the 1997 Car and
Locomotive Cyclopedia. That illustration was provided to the Cyclopedia
courtesy of Brenco Inc., of
Petersburg, Virginia.
In greater detail, bearing 750 is an assembly of parts including an inner ring
760, a pair of
tapered roller assemblies 762 whose inner ring engages axle 752, and an outer
ring member 764
whose inner frustoconical bearing surfaces engage the rollers of assemblies
762. The entire
assembly, including seals, spacers, and backing ring is held in place by an
end cap 766 mounted to
the end of axle 752. In the assembly of Figures 22a to 22c, does not employ a
round cylindrical outer
ring member, but rather, ring member 764 is made with an upper portion 770
having the same general
shape and function as bearing adapter 44 or 144, including tapered end walls
768 for rocking motion
travel limiting abutment against the surfaces of the pedestal jaws 130 as
described above. Further,
upper portion 770 includes corner abutments 774 for bracketing jaws 130,
again, as described above.
Thus a bearing is provided with an integrally formed rocking surface. The
rocking surface is
permanently fixed with relation to the remainder of the underlying bearing
assembly. In this way, an
assembly is provided in which rotation of the bearing housing is inhibited
relative to the rocking
surface.
In Figures 23a and 23b, an integrated bearing and bearing adapter rocker
assembly, or
wheelset to pedestal interface assembly, is indicated as modified bearing 790.
In this case the outer
ring 792 has been formed in the shape of a laterally extending, cylindrical
rocker surface 794, such as
a male surface (although it could be female as discussed above), for engaging
the mating female
(although, as discussed, it could be male) laterally rocker surface 796 of
pedestal seat 798, such as
may tend to provide weight-proportional self steering, as discussed above.
Thus, the embodiments of Figures 22a and 23a both show a sideframe pedestal to
axle
bearing interface assembly for a three piece rail road car truck. The assembly
of the embodiment
of Figure 22a has fittings that are operable to rock both laterally and
longitudinally. Both
embodiments include bearing assemblies having one of the rocking surface
fittings, whether male
or female, of saddle shape, formed as an integral portion of the outer ring of
the bearing, such that
the location of the rolling contact surface is rigidly located relative to the
bearing (because, in this
instance, it is part of the bearing). In the embodiment of Figure 22a, the
integrally firmed surface
is a compound surface, whereas in the embodiment of Figure 23b, the rolling
contact surface is a
cylindrical surface, which may be formed on an arc of constant radius of
curvature.
The possible permutations of surface types include those indicated above in
terms of a two
element interface (i.e., the rocking surface on the top of the bearing, and
the mating rocking
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surface on the pedestal seat) or a three element interface, in which an
intermediate rocking
member is mounted between (a) the surface rigidly located with respect to the
bearing races, and
(b) the surface of the pedestal seat. As above, one or another of the surfaces
may be formed on a
spherical arc portion such that the fittings are torsionally compliant, or,
put alternatively,
torsionally de-coupled with respect to rotation about the vertical axis. The
permutations may also
include the use of resilient pads such as members 156, 374, 412, or 456, as
may be appropriate.
Each of the assemblies of Figures 22a and 23a has a bearing for mounting to
one end of an
axle of a wheelset of a three-piece railroad car truck. The bearing has an
outer member mounted
in a position to permit the end of the axle to rotate relative thereto,
inasmuch as the inner ring is
to
intended to rotate with respect to the outer ring. The bearing has an
axis of rotation, about which
its rings and bearings are concentric that, when installed, may tend to be
coincident with the
longitudinal axis of the axis of the axle of the wheelset. In each case, the
outer member has a
rocking surface formed thereon for engaging a mating rolling contact surface
of a pedestal seat
member of a sideframe of the three piece truck.
The rolling contact surface of the bearing has a local minimum energy
condition when
centered under the corresponding seat, and it is preferred that the mating
rolling contact surface be
given a radius that may tend to encourage self centering of the male rolling
contact element. That
is to say, displacement from the minimum energy position (preferably the
centered position) may
tend to cause the vertical separation distance between the centerline of the
wheelset axis (and
hence the centreline of the axis of rotation of the bearing) to become more
distantly spaced from
the sideframe pedestal roof, since the rocking action may tend marginally to
raise the end of the
sideframe, thus increasing the stored potential energy in the system.
This can be expressed differently. In cylindrical polar co-ordinates, the long
axis of the
wheelset axle may be considered as the axial direction. There is a radial
direction measured
perpendicularly away from the axial direction, and there is an angular
circumferential direction
that is mutually perpendicular to both the axial direction, and the radial
direction. There is a
location on the rolling contact surface that is closer to the axis of rotation
of the bearing than any
other location. This defines the "rest" or local minimum potential energy
equilibrium position.
Since the radius of curvature of the rolling contact surface is greater than
the radial length, L,
between the axis of rotation of the bearing and the location of minimum
radius, the radial distance,
as a function of circumferential angle 0 will increase to either side of the
location of minimum
radius (or, put alternatively, the location of minimum radial distance from
the axis of rotation of
the bearing lies between regions of greater radial distance). Thus the slope
of the function r(0),
namely dr/d0, is zero at the minimum point, and is such that r increases at an
angular
displacement away from the minimum point to either side of the location of
minimum potential
energy. Where the surface has compound curvature, both dr/d0 and dr/dL are
zero at the
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minimum point, and are such that r increases to either side of the location of
minimum energy to
all sides of the location of minimum energy, and zero at that location. This
may tend to be true
whether the rolling contact surface on the bearing is a male surface or a
female surface or a saddle,
and whether the center of curvature lies below the center of rotation of the
bearing, or above the
rolling contact surfaces. The curvature of the rolling contact surface may be
spherical, ellipsoidal,
toroidal, paraboloid, parabolic or cylindrical. The rolling contact surface
has a radius of curvature,
or radii of curvature, if a compound curvature is employed, that is, or are,
larger than the distance
from the location of minimum distance from the axis of rotation, and the
rolling contact surfaces
are not concentric with the axis of rotation of the bearing.
Another way to express this is to note that there is a first location on the
rolling contact
surface of the bearing that lies radially closer to the axis of rotation of
the bearing than any other
location thereon. A first distance, L is defined between the axis of rotation,
and that nearest
location. The surface of the bearing and the surface of the pedestal seat each
have a radius of
curvature and mate in a male and female relationship, one radius of curvature
being a male radius
of curvature ri, the other radius of curvature being a female radius of
curvature, R2, (whichever it
may be). ri is greater than L, R2 is greater than r1, and L, r1 and R2 conform
to the formula 1:1 -
(r1-1 - > 0, the rocker surfaces being co-operable to permit self
steering.
Figures 24a to 24e
Figures 24a to 24e relate to a three piece truck 200. Truck 200 has three
major elements,
those elements being a truck bolster 192, that is symmetrical about the truck
longitudinal
centreline, and a pair of first and second side frames, indicated as 194. Only
one side frame is
shown in Figure 14c given the symmetry of truck 200. Three piece truck 200 has
a resilient
suspension (a primary suspension) provided by a spring group 195 trapped
between each of the
distal (i.e., transversely outboard) ends of truck bolster 192 and side frames
194.
Truck bolster 192 is a rigid, fabricated beam having a first end for engaging
one side frame
assembly and a second end for engaging the other side frame assembly (both
ends being indicated
as 193). A center plate or center bowl 190 is located at the truck center. An
upper flange 188
extends between the two ends 194, being narrow at a central waist and flaring
to a wider
transversely outboard termination at ends 194. Truck bolster 192 also has a
lower flange 189 and
two fabricated webs 191 extending between upper flange 188 and lower flange
189 to form an
irregular, closed section box beam. Additional webs 197 are mounted between
the distal portions
of flanges 188 and 189 where bolster 192 engages one of the spring groups 195.
The transversely
distal region of truck bolster 192 also has friction damper seats 196, 198 for
accommodating
friction damper wedges.
Side frame 194 may be a casting having pedestal fittings 40 into which bearing
adapters
44, bearings 46, and a pair of axles 48 and wheels 50 mount. Side frame 194
also has a
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compression member, or top chord member 32, a tension member, or bottom chord
member 34,
and vertical side columns 36 and 36, each lying to one side of a vertical
transverse plane bisecting
truck 200 at the longitudinal station of the truck center. A generally
rectangular opening is
defined by the co-operation of the upper and lower beam members 32, 34 and
vertical sideframe
columns 36, into which end 193 of truck bolster 192 can be introduced. The
distal end of truck
bolster 192 can then move up and down relative to the side frame within this
opening. Lower
beam member 34 has a bottom or lower spring seat 52 upon which spring group
195 can seat.
Similarly, an upper spring seat 199 is provided by the underside of the distal
portion of bolster 192
which engages the upper end of spring group 195. As such, vertical movement of
truck bolster
192 will tend to increase or decrease the compression of the springs in spring
group 195.
In the embodiment of Figure 24a, spring group 195 has two rows of springs 193,
a
transversely inboard row and a transversely outboard row. In one embodiment
each row may have
four large (8 inch +/-) diameter coil springs giving vertical bounce spring
rate constant, k, for
group 195 of less than 10,000 lbs. / inch. In one embodiment this spring rate
constant may be in
the range of 6000 to 10,000 lbs. / in., and may be in the range of 7000 to
9500 lbs. / in, giving an
overall vertical bounce spring rate for the truck of double these values,
perhaps in the range of
14,000 to 18,500 lbs. / in for the truck. The spring array may include nested
coils of outer springs,
inner springs, and inner-inner springs depending on the overall spring rate
desired for the group,
and the apportionment of that stiffness. The number of springs, the number of
inner and outer
coils, and the spring rate of the various springs can be varied. The spring
rates of the coils of the
spring group add to give the spring rate constant of the group, typically
being suited for the
loading for which the truck is designed.
Each side frame assembly also has four friction damper wedges arranged in
first and
second pairs of transversely inboard and transversely outboard wedges 204,
205, 206 and 207 that
engage the sockets, or seats 196, 198 in a four-cornered arrangement. The
corner springs in spring
group 195 bear upon a friction damper wedge 204, 205, 206 or 207. Each
vertical column 36 has
a friction wear plate 92 having transversely inboard and transversely outboard
regions against
which the friction faces of wedges 204, 205, 206 and 207 can bear,
respectively. Bolster gibs 106
and 108 lie inboard and outboard of wear plate 92 respectively.
In the illustration of Figure 24e, the damper seats are shown as being
segregated by a
partition 208. If a longitudinal vertical plane is drawn through truck 200
through the center of
partition 208, it can be seen that the inboard dampers lie to one side of
plane 209, and the outboard
dampers lie to the outboard side of the plane. In hunting then, the normal
force from the damper
working against the hunting will tend to act in a couple in which the force on
the friction bearing
surface of the inboard pad will always be fully inboard of the plane on one
end, and fully outboard
on the other diagonal friction face.
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In one embodiment, the size of the spring group embodiment of Figure 24b may
yield a
side frame window opening having a width between the vertical columns 36 of
side frame 194 of
roughly 33 inches. This is relatively large compared to existing spring
groups, being more than 25
% greater in width. In the embodiment of Figure 11 truck 20 may also have an
abnormally wide
sideframe window to accommodate 5 coils each of 5 Y2" dia. Truck 200 may have
a
correspondingly greater wheelbase length, indicated as WB. WB may be greater
than 73 inches,
or, taken as a ratio to the track gauge width, may be greater than 1.30 time
the track gauge width.
It may be greater than 80 inches, or more than 1.4 times the gauge width, and
in one embodiment
is greater than 1.5 times the track gauge width, being as great, or greater
than, about 84 inches.
Similarly, the side frame window may be wider than tall. The measurement
across the wear plate
faces between the opposed side frame columns 36 may be greater than 24",
possibly in the ratio of
greater than 8:7 of width to height, and possibly in the range of 28" or 32"
or more, giving ratios
of greater than 4:3 and greater than 3:2. The spring seat may have lengthened
dimensions to
correspond to the width of the side frame window, and a transverse width of 15
Y2 - 17" or more.
Figures 25a to 25d
Figures 25a to 25d, show an alternate truck embodiment. Truck 800 has a
bolster 808,
side frame 807 and damper 801, 802 installation that employs constant force
inboard and
outboard, fore and aft pairs of friction dampers 801, 802 independently sprung
on horizontally
acting springs 803, 804 housed in side-by-side pockets 805, 806 mounted in the
ends of truck
bolster 808. While only two dampers 801, 802 are shown, a pair of such dampers
faces toward
each of the opposed side frame columns. Dampers 801,802 may each include a
block 809 and a
consumable wear member 810 mounted to the face of block 809. The block and
wear member
have mating male and female indexing features 812 to maintain their relative
position. A
removable grub screw fitting 814 is provided in the spring housing to permit
the spring to be pre-
loaded and held in place during installation. Springs 803,804 urge, or bias,
friction dampers 801,
802 against the corresponding friction surfaces of the sideframe columns. The
deflection of
springs 803, 804 does not depend on compression of the main spring group 816,
but rather is a
function of an initial pre-load.
Figures 26a and 26b
Figures 26a and 26b show a partial isometric view of a truck bolster 820 that
is generally
similar to truck bolster 402 of Figure 14a, except insofar as bolster pocket
822 does not have a
central partition like web 452, but rather has a continuous bay extending
across the width of the
underlying spring group, such as spring group 436. A single wide damper wedge
is indicated as
824. Damper 824 is of a width to be supported by, and to be acted upon, by two
springs 825, 826
of the underlying spring group. In the event that bolster 400 may tend to
deflect to a non-
perpendicular orientation relative to the associated side frame, as in the
parallelogramming
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phenomenon, one side of wedge 824 may tend to be squeezed more tightly than
the other, giving
wedge 824 a tendency to twist in the pocket about an axis of rotation
perpendicular to the angled
face (i.e., the hypotenuse face) of the wedge. This twisting tendency may also
tend to cause
differential compression in springs 825, 826, yielding a restoring moment both
to the twisting of
wedge 824 and to the non-square displacement of truck bolster 820 relative to
the truck side
frame. There may tend to be a similar moment generated at the opposite spring
pair at the
opposite side column of the side frame. Figure 26b shows an alternate pair of
damper wedges
827, 828. This dual wedge configuration can similarly seat in bolster pocket
822, and, in this case,
each wedge 827, 828 sits over a separate spring. Wedges 827, 828 are slidable
relative to each
other along the primary angle of the face of bolster pocket 822. When the
truck moves to an out
of square condition, differential displacement of wedges 827,828 may tend to
result in differential
compression of their associated springs, e.g., 825, 826 resulting in a
restoring moment. In either
case, the bolster pockets may have wear liners 494, and the pockets themselves
may be part of
prefabricated inserts 506 to be welded to the end of the bolster, either at
original manufacture or
retro-fit, such as might include installation of wider sideframe columns, and
a different spring
group selection such as might accompany a retrofit conversion from a single
damper to a double
damper (i.e., four cornered) arrangement.
Figures 27a and 27b
Figure 27a shows a bolster 830 that is similar to bolster 210 except insofar
as bolster
pockets 831,832 each accommodate a pair of split wedges 833, 834. Pockets 831,
832 each have
a pair of bearing surfaces 835, 836 that are inclined at both a primary angle
a and a secondary
angle (3, the secondary angles of surfaces 835 and 836 being of opposite hand
to yield the damper
separating forces discussed above. Surfaces 835 and 836 are also provided with
linings in the
nature of relatively low friction wear plates 837, 838. Each pair of split
wedges seats over a single
spring.
The example of Figure 27b shows a combination of a bolster 840 and biased
split wedges
841, 842. Bolster pockets 843, 844 are stepped pockets in which the steps,
e.g., items 845, 846,
have the same primary angle a, and the same secondary angle 13, and are both
biased in the same
direction, unlike the symmetrical faces of the split wedges in Figure 27a,
which are left and right
handed. Thus the outboard pair of split wedges 842 has first and second
members 847, 848 each
having primary angle a and secondary angle p of the same hand, both members
being biased in the
outboard direction. Similarly, the inboard pair of split wedges 841 has first
and second members
849,850 having primary angle a, and secondary angle p, except that the sense
of secondary angle
13 is such that members 849 and 850 tend to be driven in the inboard
direction. In the arrangement
of Figures 27c a single stepped wedge 851,852 may be used in place of the pair
of split wedges
e.g., members 847,848 or 849, 850. A corresponding wedge of opposite hand is
used in the other
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bolster pocket.
Figures 28a and 28b
In Figure 28a, a truck bolster 860 has welded bolster pocket inserts 861, 862
of opposite
hands welded into accommodations in its end. Each bolster pocket has inboard
and outboard
portions 863, 864 that share the same primary angle a, but have secondary
angles ri that are of
opposite hand. Respective inboard and outboard wedges are indicated as 865,
866, each seating
over a vertically oriented spring 867, 868. In this case bolster 860 is
similar to bolster 820 of
Figure 26a, to the extent that there is no land separating the inner and outer
portions of the bolster
pocket. Bolster 860 is also similar to bolster 210 of Figure 5, except that
the bolster pockets of
to
opposite hand are merged without an intervening land. In Figure 28b, split
wedge pairs 869,870
(inboard) and 871, 872 (outboard) are employed in place of the single inboard
and outboard
wedges 865 and 866.
Figures 29a ¨ 29c
Figures 29a ¨ 29c illustrate an alternate embodiment of bolster gib and
sideframe inter-
relationship, such as may be incorporated in a truck such as truck 20, or 22,
or other truck shown
or described herein. In the embodiment of Figures 29a - 29c, truck 900 has a
bolster 902 and
sideframes 904. It may be that a type or railroad freight car, such as a coal
car, in which truck 900
might be employed, for example, may be operated in the light car (i.e., empty)
condition, as when
being returned to a location for loading once again with lading. Such a car,
or string of such cars,
may be dragged or pushed in the empty condition on not necessarily the best
track, with relatively
sharp curves. In such a condition, the lateral forces imposed on the truck may
be proportionately
great relative to the vertical force on the truck due to gravity acting on the
car. The ratio of these
forces is sometimes referred to as the LN ratio. In such circumstances it may
be appropriate to
have a relatively small allowance for lateral travel of the bolster relative
to the sideframes. With a
fully laden car, however, the LN ratio may be low, or lower, and a tight
bolster gib spacing may
not yield the most desirable result with respect to wear on the rails. A wider
gib spacing for a
fully laden car may permit a larger lateral excursion before contact occurs
between the bolster gib
and sideframe, and so may yield a more desirable overall ride quality.
Truck 900 may have one of the sideframe to wheelset interface assemblies of
one or
another of the embodiments described herein, which, as noted, may include a
lateral rocking
fitting. Bolster 902 may have at each end thereof, and on each fore and aft
face thereof (being
symmetrical about its central axis and being symmetrical about its long axis)
an inboard bolster
gib 906, and an outboard bolster gib 908. Inboard bolster gib 906 may be
mounted inboard of the
most laterally inboard portion of the bolster damper pockets 910, and outboard
bolster gib 908
may be mounted outboard of the most outboard portion of the bolster pocket,
912, and may be
mounted to the distal extremity of bolster 902. Although truck 900 may have a
four cornered
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damper, or double damper, arrangement as in truck 20 or 22, a tapered gib
arrangement such as
here described, may be employed with a single damper installation, as in truck
250 of Figure le.
Inboard gib 906 may have a body 914 extending generally perpendicularly away
from the
front face web 916 of bolster 902, and may have an abutment surface 918 facing
toward the
sideframe column 920, and, more specifically, toward a stop identified as a
sideframe column
abutment face 922 that lies on the laterally inboard margin of the reinforced
wear plate backing
frame portion 924 of sideframe column 920. When viewed in profile, (that is to
say looking
parallel to the long axis of the sideframe), abutment surface 918 may be
inclined, and may be
inclined linearly, such as at an angle gamma, y, from the vertical on a slope
that extends upward
and inboard, downward and outboard. Similarly, abutment face 922 may also be
relieved at angle
gamma y. As the vertical deflection of the spring group 915 increases, the
lateral translational
gap, i.e., the gap measured on the horizontal plane, of the light car
condition, indicated in Figure
29c as G1' as the horizontal distance between surface 918 and surface 922, may
also tend to
increase such that the clearance may differ for different at rest positions of
the bolster according to
the amount of lading carried by the car as indicated by the larger lateral
dimension of the gap,
indicated as 'G2' in Figure 29d. The lateral translational gap 'G2' may
correspond to the gap size
in the at rest position of a fully laden car. 'G2' and `G1' are measures of
allowance for lateral
translation of the bolster relative to the sideframe, and in some embodiments
may be related to the
vertical spring displacement between the two, G2
8springtally. In the instance where the
opposed surfaces are planar and parallel, the gap width normal to the opposed
surfaces is G2Cosy,
or GiCosy respectively. In operation, lateral translation of bolster 902
relative to sideframe 904
may tend to urge surfaces 916 and 920 toward (or away) from each other, with
the limit of travel
being reached when they abut. As may be appreciated, lateral travel in one
direction may cause
abutting contact with the gib stop on one sideframe, while lateral travel in
the opposite direction
may yield abutting contact with the gib stop on the other sideframe such that
the lateral travel is
bounded in both directions. The upper or lower, or both, vertices of surface
918 may have
relatively generous radii 925.
It may be that the at rest spacing `P' of the outboard bolster gib may be
comparable to, or
slightly greater than, the at rest spacing of the inboard gib from the stop on
the sideframe at the
fully laden condition. That is, dimension 'P' may be greater than dimension
`G2' when bolster
902 is in its at rest position in the fully laden condition. In one
embodiment, 'P' may be in the
range of 1 to 1 3/8 inches, and may be about 1 ¨ 1/4 inches. In one embodiment
`G1' may be in the
range of 3/8 to 5/8 inches, and may be about 1/2 inch in the light car
condition, and 'G2' may be in
the range of 1 inch to 1 1/4 inches in the fully laden condition, and may be
in the range of 1 1/4 to 1
1/2 inches, and may be about 1 3/8 inches in the full travel "solid" condition
of the spring group. In
some embodiments the outboard gib 908 may have a vertical, planar abutment
surface as
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illustrated in Figures 29a to 29d, and may serve primarily to prevent escape
of sideframe 904 from
bolster 902. In other embodiments outboard gib 908 may also have a tapered
abutment contact
surface 926 as illustrated in Figure 29e in the manner of gib 906, and the
outboard abutment
surface or stop 928 of sideframe column 920 may also be tapered.
Angle gamma, y, may lie in the range of about tan' (11/16) to tan' (2/16), or,
alternatively, about 5 degrees to about 40 degrees, and in one embodiment the
incremental slope
relating increased lateral spacing to increased at rest deflection of the main
spring groups may be
about 7/16 inches of additional travel per inch of additional vertical
deflection, (+/-25%).
Although the embodiments of Figures 29a ¨ 29d may employ gibs and mating, co-
operation stops of identical profiles, being mating positive and negative
images such as surfaces
918 and 922, this need not necessarily be so. In another embodiment, as shown
in Figure 29f, an
abutment may have a non-straight edge form, as indicated by arcuate surface
930, which may
follow a circular or parabolic arc for contact with a mating face, such as
linear face 932. The arc
may have a local radius of curvature Ro. The arcuate surface 930 may be formed
such that the
point of tangency (when abutting the stop) is at the mid point of the arc. It
may also be understood
that the arcuate surface is formed on the sideframe column, while the other
surface could be
formed on the gib, i.e., the relationship could be reversed.
Figures 30a ¨ 30g
An alternate form of damper assembly 940 is illustrated in Figures 30a to 30g.
Damper
assembly 940 may include a wedge body 942 and a friction member 944 matingly
engageable
with body 942. In this instance, friction member 944 may be a replaceable
member that seats in a
forwardly facing socket 946 formed in body 942. Although socket 946 may have a
female form,
and friction member 944 may have a corresponding male form, this could be
reversed, with the
illustrations of Figures 30a to 30g being intended to be generically
representative in this regard,
without the need for duplication of the drawings in the reversed male and
female roles. Friction
member 944 may have a rearwardly protruding bulge having an engagement
interface surface 948
that is formed on a body of revolution, and that may have a compound curvature
with radii of
curvature about both an horizontal axis 'y' and a vertical axis 'z'. Socket
946 may have a mating
engagement interface surface 950 of complementary compound curvature.
Furthermore, either or
both of surfaces 948 and 950 may be treated to reduce friction therebetween,
as by applying a
polymeric or other sliding surface layer or treatment. A lubricant, which may
be a solid lubricant,
may be used between surfaces 948 and 950 as may a coating, such as an anti-
galling coating.
To the extent that the bolster may flex to a non-square condition with respect
to the
sideframe columns, or to the extent that there may be a relative rise or fall
between the leading and
trailing wheels of the sideframe such that the sideframe rotates about the
long axis of the truck
bolster, friction member 944 may tend to be urged to pitch or yaw relative to
the bolster, while
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maintaining friction face 952 in planar contact with the opposing sideframe
column wear plate.
The use of mating curvatures on surfaces 948 and 950, which may be mating
spherical curvatures,
may give degrees of freedom of rotation about the 'y' and 'z' axes to
accommodate a measure of
angular displacement of friction member 944 relative to body 942 under those
pitch and yaw
conditions. The hypotenuse face 954 of body 942 may be planar (that is, it may
lack the crown
discussed hereinabove), and may have primary and secondary angles as discussed
above. The
base, or spring seat socket side 960 of body 942 may be as above, and may have
a skirt, or skirt
array of depending members 961, 962, 963 for capturing the upper end of a
spring, such as
indicated as 938. Friction member 944 may be formed of a compound having known
friction
properties throughout, or may have a back portion 956 for seating against body
942, and a front
portion, or friction face portion 958 as it may be termed, that may be a layer
or pad having known
friction properties such as those types of coatings, or surfaces or pads
described elsewhere herein.
The front and back portions 958, 956 may be releaseably engageable, or
releaseably mutually
interlocking, or, alternatively, may be cast or bonded together in a permanent
or substantially
permanent manner. Body 942 may also have spaced apart, parallel planar side
faces 964, 966, that
may slide in planar relationship against an end face of the corresponding
bolster pocket. While
face portion 958 may have a circular friction face 952, it could also be
extended to have a non-
circular face, such as generally square or rectangular contact footprint
against the sideframe
column wear plate, such as when the compound curvature has different radii of
curvature about
the z and y axes. In use, when the friction compound, for example, portion
958, has been worn
away in large measure, be it V2 , % , 3/4 of the original material being worn
away, or some other
wear criteria having been surpassed, then friction member 944 may be extracted
during servicing
and a new or re-built friction member 944 may be installed instead.
Compound Pendulum Geometry
The various rockers shown and described herein may employ rocking elements
that define
compound pendulums ¨ that is, pendulums for which the male rocker radius is
non-zero, and there
is an assumption of rolling (as opposed to sliding) engagement with the female
rocker. The
embodiment of Figure 2a (and others) for example, shows a bi-directional
compound pendulum.
The performance of these pendulums may affect both lateral stiffness and self-
steering on the
longitudinal rocker.
The lateral stiffness of the suspension may tend to reflect the stiffness of
(a) the sideframe
between (i) the bearing adapter and (ii) the bottom spring seat (that is, the
sideframes swing
laterally); (b) the lateral deflection of the springs between (i) the lower
spring seat and (ii) the
upper spring seat mounting against the truck bolster, and (c) the moment
between (i) the spring
seat in the sideframe and (ii) the upper spring mounting against the truck
bolster. The lateral
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stiffness of the spring groups may be approximately 1/2 of the vertical spring
stiffness. For a 100
or 110 Ton truck designed for 263,000 or 286,000 lbs GRL, vertical spring
group stiffness might
be 25 ¨ 30,000 lbs./in., assuming two groups per truck, and two trucks per
car, giving a lateral
spring stiffness of 13 ¨ 16,000 lbs./in. The second component of stiffness
relates to the lateral
rocking deflection of the sideframe. The height between the bottom spring seat
and the crown of
the bearing adapter might be about 15 inches (+/-). The pedestal seat may have
a flat surface in
line contact on a 60 inch radius bearing adapter crown. For a loaded 286,000
lbs. car, the apparent
stiffness of the sideframe due to this second component may be 18,000 ¨ 25,000
lbs./in, measured
at the bottom spring seat. Stiffness due to the third component, unequal
compression of the
springs, is additive to sideframe stiffness.
An alternate truck is the "Swing Motion" truck, such as shown at page 716 in
the 1980 Car
and Locomotive Cyclopedia (1980, Simmons-Boardman, Omaha). In a swing motion
truck, the
sideframe may act more like a pendulum. The bearing adapter may have a female
rocker, of
perhaps 10 in. radius. A mating male rocker mounted in the pedestal roof may
have a radius of
perhaps 5 in. Depending on the geometry, this may yield a sideframe resistance
to lateral
deflection in the order of VI (or less) to about 1/2 of what might otherwise
be typical. If combined
with the spring group stiffness, the relative softness of the pendulum may be
dominant. Lateral
stiffness may then be less governed by vertical spring stiffness. Use of a
rocking lower spring seat
may reduce, or eliminate, lateral stiffness due to unequal spring compression.
Swing motion
trucks have used transoms to link the side frames, and to lock them against
non-square
deformation. Other substantially rigid truck stiffening devices such as
lateral unsprung rods or a
"frame brace" of diagonal unsprung bracing have been used. Lateral unsprung
bracing may
increase resistance to rotation of the sideframes about the long axis of the
truck bolster. This may
not necessarily enhance wheel load equalisation or discourage wheel lift.
A formula may be used for estimation of truck lateral stiffness:
krruck = 2 x [ (ksideframeY1 + (kspring shear)]i
where
kstdeframe [kpendulum + kspring moment
kspring shear = The lateral spring constant for the spring group in
shear.
kpendulum = The force required to deflect the pendulum per unit of
deflection, as
measured at the center of the bottom spring seat.
kspring moment = The force required to deflect the bottom spring seat per unit
of sideways
deflection against the twisting moment caused by the unequal compression
of the inboard and outboard springs.
In a pendulum, the relationship of weight and deflection is roughly linear for
small angles,
analogous to F = la, in a spring. A lateral constant can be defined as
kpendulum = W / L, where W is
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weight, and L is pendulum length. An approximate equivalent pendulum length
can be defined as
Leg = W / kpendulum. W is the sprung weight on the sideframe. For a truck
having L= 15 and a 60"
crown radius, Leg might be about 3 in. For a swing motion truck, Leg may be
more than double
this.
A formula for a longitudinal (i.e., self-steering) rocker as in Figure 2a, may
also be
defined:
F king = klong = (AV L) [ [ (1 / L) / (1 In¨ 1 RI) ¨ 1]
Where:
klong is the longitudinal constant of proportionality between longitudinal
force and
to longitudinal deflection for the rocker.
F is a unit of longitudinal force, applied at the centerline of the axle
along is a unit of longitudinal deflection of the centreline of the axle
L is the distance from the centreline of the axle to the apex of male portion
116.
R1 is the longitudinal radius of curvature of the female hollow in the
pedestal seat 38.
r1 is the longitudinal radius of curvature of the crown of the male portion
116 on the bearing
adapter
In this relationship, R1 is greater than r, and (1 / L) is greater than [(1 /
n) ¨(1 / R1)], and, as
shown in the illustrations, L is smaller than either n or 111. In some
embodiments herein, the length
L from the center of the axle to apex of the surface of the bearing adapter,
at the central rest position
may typically be about 5 ¨ 3/4 to 6 inches (+/-), and may be in the range of 5
¨ 7 inches. Bearing
adapters, pedestals, side frames, and bolsters are typically made from steel.
The present inventor is of
the view that the rolling contact surface may preferably be made of a tool
steel, or a similar material.
In the lateral direction, an approximation for small angular deflections is:
kpenduium = (F2/62) = (W/Lpend.)[[ (1 / Lpend.) ((1 RRocker) (1 / RSeat))] +
1]
where:
kpeadatuat = the lateral stiffness of the pendulum
F2 = the force per unit of lateral deflection applied at the bottom spring
seat
82 = a unit of lateral deflection
W = the weight borne by the pendulum
Lpend.= the length of the pendulum, as undeflected, between the contact
surface of the
bearing adapter to the bottom of the pendulum at the spring seat
RRocker = r2 the lateral radius of curvature of the rocker surface
Rseat = R2 = the lateral radius of curvature of the rocker seat
Where Rseat and RRocker are of similar magnitude, and are not unduly small
relative to L,
the pendulum may tend to have a relatively large lateral deflection constant.
Where RSeat is large
compared to L or RRocker, or both, and can be approximated as infinite (i.e.,
a flat surface), this
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formula simplifies to:
kpendulum = (Flateral Olateral) = (W1 I Lpend.)[(RRocker 1 Lpendulum) 11
Using this number in the denominator, and the design weight in the numerator
yields an
equivalent pendulum length, Leg. = W / kpendulum
The sideframe pendulum may have a vertical length measured (when undeflected)
from the
rolling contact interface at the upper rocker seat to the bottom spring seat
of between 12 and 20
inches, perhaps between 14 and 18 inches. The equivalent length Leg, may be in
the range of
greater than 4 inches and less than 15 inches, and, more narrowly, 5 inches
and 12 inches,
depending on truck size and rocker geometry. Although truck 20 or 22 may be a
70 ton special, a
70 ton, 100 ton, 110 ton, or 125 ton truck, truck 20 or 22 may be a truck size
having 33 inch
diameter, or 36 or 38 inch diameter wheels. In some embodiments herein, the
ratio of male rocker
radius ilkoekõ to pendulum length, Lpend., may be 3 or less, in some instances
2 or less. In laterally
quite soft trucks this value may be less than 1. The factor [ (1 / Lpend.) ((1
RRocker) ¨ (1 /
RSeat))1, may be less than 3, and, in some instances may be less than 2 Y2. In
laterally quite soft
trucks, this factor may be less than 2. In those various embodiments, the
lateral stiffness of the
lateral rocker pendulum, calculated at the maximum truck capacity, or the GRL
limit for the
railcar more generally, may be less than the lateral shear stiffness of the
associated spring group.
Further, in those various embodiments the truck may be free of lateral
unsprung bracing, whether
in terms of a transom, laterally extending parallel rods, or diagonally criss-
crossing frame bracing
or other unsprung stiffeners. In those embodiments the trucks may have four
cornered damper
groups driven by each spring group.
In the trucks described herein, for their fully laden design condition which
may be
determined either according to the AAR limit for 70, 100, 110 or 125 ton
trucks, or, where a lower
intended lading is chosen, then in proportion to the vertical sprung load
yielding 2 inches of
vertical spring deflection in the spring groups, the equivalent lateral
stiffness of the sideframe,
being the ratio of force to lateral deflection, measured at the bottom spring
seat, may be less than
the horizontal shear stiffness of the springs. In some embodiments,
particularly for relatively low
density fragile, high valued lading such as automobiles, consumer goods, and
so on, the equivalent
lateral stiffness of the sideframe ksideframe may be less than 6000 lbs./in.
and may be between about
3500 and 5500 lbs./in., and perhaps in the range of 3700 ¨ 4100 lbs./in. For
example, in one
embodiment a 2 x 4 spring group has 8 inch diameter springs having a total
vertical stiffness of
9600 lbs./ in. per spring group and a corresponding lateral shear stiffness
kspring shear Of 8200 lbs./in.
The sideframe has a rigidly mounted lower spring seat. It may be used in a
truck with 36 inch
wheels. In another embodiment, a 3 x 5 group of 51/2 inch diameter springs is
used, also having a
vertical stiffness of about 9600 lbs./in., in a truck with 36 inch wheels. It
may be that the vertical
spring stiffness per spring group lies in the range of less than 30,000
lbs./in., that it may be in the
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range of less than 20,000 lbs./in and that it may perhaps be in the range of
4,000 to 12000 lbs./in,
and may be about 6000 to 10,000 lbs./in. The twisting of the springs, kspring
moment, may have a
stiffness in the range of 750 to 1200 lbs./in. and a horizontal shear
stiffness in the range of 3500 to
5500 lbs./in. with an overall sideframe stiffness in the range of 2000 to 3500
lbs./in.
In the embodiments of trucks having a fixed bottom spring seat, the truck may
have a
portion of stiffness, attributable to unequal compression of the springs
equivalent to 600 to 1200
lbs./in. of lateral deflection, when the lateral deflection is measured at the
bottom of the spring seat
on the sideframe. This value may be less than 1000 lbs./in., and may be less
than 900 lbs./in. The
portion of restoring force attributable to unequal compression of the springs
may tend to be greater
for a light car as opposed to a fully laden car.
Some embodiments, including those that may be termed swing motion trucks, may
have
one or more features, namely that, in the lateral swinging direction r/R <
0.7; 3" <r < 30", or more
narrowly, 4" <r < 20"; and 5" <R < 45", or more narrowly, 8" <R < 30", and in
lateral stiffness,
2,000 lbs/in < kpendulum < 10,000 lbs/in, or expressed differently, the
lateral pendulum stiffness in
pounds per inch of lateral deflection at the bottom spring seat where vertical
loads are passed into
the sideframe, per pound of weight carried by the pendulum, may be in the
range of 0.08 and 0.2,
or, more narrowly, in the range of 0.1 to 0.16.
Friction Surfaces
Dynamic response may be quite subtle. It is advantageous to reduce resistance
to curving,
and self steering may help in this regard. It is advantageous to reduce the
tendency for wheel lift
to occur. A reduction in stick-slip behaviour in the dampers may improve
performance in this
regard. Employment of dampers having roughly equal upward and downward
friction forces may
discourage wheel lift. Wheel lift may be sensitive to a reduction in torsional
linkage between the
sideframes, as when a transom or frame brace is removed. While it may be
desirable torsionally to
decouple the sideframes it may also be desirable to supplant a physically
locked relationship with
a relationship that allows the truck to flex in a non-square manner, subject
to a bias tending to
return the truck to its squared position such as may be obtained by employing
the larger resistive
moment couple of doubled dampers as compared to single dampers. While use of
laterally soft
rockers, dampers with reduced stick slip behaviour, four-cornered damper
arrangements, and self
steering may all be helpful in their own right, it appears that they may also
be inter-related in a
subtle and unexpected manner. Self steering may function better where there is
a reduced
tendency to stick slip behaviour in the dampers. Lateral rocking in the swing
motion manner may
also function better where the dampers have a reduced tendency to stick slip
behaviour. Lateral
rocking in the swing motion manner may tend to work better where the dampers
are mounted in a
four cornered arrangement. Counter-intuitively, truck hunting may not worsen
significantly when
the rigidly locked relationship of a transom or frame brace is replaced by
four cornered dampers
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(apparently making the truck softer, rather than stiffer), and where the
dampers are less prone to
stick slip behaviour. The combined effect of these features may be
surprisingly interlinked.
In the various truck embodiments described herein, there is a friction damping
interface
between the bolster and the sideframes. Either the sideframe columns or the
damper (or both) may
have a low or controlled friction bearing surface, that may include a hardened
wear plate, that may
be replaceable if worn or broken, or that may include a consumable coating or
shoe, or pad. That
bearing face of the motion calming, friction damping element may be obtained
by treating the
surface to yield desired co-efficients of static and dynamic friction whether
by application of a
surface coating, and insert, a pad, a brake shoe or brake lining, or other
treatment. Shoes and
linings may be obtained from clutch and brake lining suppliers, of which one
is Railway Friction
Products. Such a shoe or lining may have a polymer based or composite matrix,
loaded with a
mixture of metal or other particles of materials to yield a specified friction
performance. Shoes
and linings may be replaceable, as indicated, for example in US Patent 6,
374,749 of Duncan, or
US Patent 6, 701, 850 of McCabe et al.
That friction surface may, when employed in combination with the opposed
bearing surface,
have a co-efficient of static friction, ft, and a co-efficient of dynamic or
kinetic friction, Ilk. The
coefficients may vary with environmental conditions. For the purposes of this
description, the
friction coefficients will be taken as being considered on a dry day condition
at 70 F. In one
embodiment, when dry, the coefficients of friction may be in the range of0.15
to 0.45, maybe in the
narrower range of0.20 to 0.35, and, in one embodiment, may be about 0.30. In
one embodiment that
coating, or pad, may, when employed in combination with the opposed bearing
surface of the
sideframe column, result in coefficients of static and dynamic friction at the
friction interface that are
within 20%, or, more narrowly, within 10% of each other. In another
embodiment, the coefficients
of static and dynamic friction are substantially equal. It may be that an
elastomeric material may be
employed as described in US Patent Re 31784 or Re 31,988 both of Wiebe.
Sloped Wedge Surface
Where damper wedges are employed, a generally low friction, or controlled
friction pad or
coating may also be employed on the sloped surface of the damper that engages
the wear plate (if
such is employed) of the bolster pocket where there may be a partially
sliding, partially rocking
dynamic interaction. A controlled friction interface between the slope face of
the wedge and the
inclined face of the bolster pocket, in which the combination of wear plate
and friction member
may tend to yield coefficients of friction of known properties, may be used. A
polymeric surface,
or pad having these friction properties may be used, as may a suitable clutch
or brake lining
material. In some embodiments those coefficients may be the same, or nearly
the same, and may
have little or no tendency to exhibit stick-slip behaviour, or may have a
reduced stick-slip
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tendency as compared to cast iron on steel. Further, the use of brake linings,
or inserts of cast
materials having known friction properties may tend to permit the properties
to be controlled
within a narrower, more predictable and more repeatable range such as may
yield a reasonable
level of consistency in operation. The coating, or pad, or lining, may be a
polymeric element, or an
element having a polymeric or composite matrix loaded with suitable friction
materials. It may be
obtained from a brake or clutch lining manufacturer, or the like. One such
firm that may be able to
provide such friction materials is Railway Friction Products of 13601
Laurinburg Maxton Ai, Maxton
NC; another may be Quadrant EPP USA Inc., of 2120 Fairmont Ave., Reading PA.
In one
embodiment, the material may be the same as that employed by the Standard Car
Truck Company in
the "Barber Twin Guard" (t.m.) damper wedge with polymer covers. In one
embodiment the material
may be such that a coating, or pad, may, when employed with the opposed
bearing surface of the
sideframe column, result in coefficients of static and dynamic friction at the
friction interface that are
within 20%, or more narrowly, within 10 % of each other. In another
embodiment, the coefficients of
static and dynamic friction are substantially equal. The co-efficient of
dynamic friction may be in the
range of 0.15 to 0.30, and in one embodiment may be about 0.20.
A damper may be provided with a friction specific treatment, whether by
coating, pad or
lining, on both the vertical friction face and the slope face. The
coefficients of friction on the slope
face need not be the same as on the friction face, although they may be. In
one embodiment it may be
that the coefficients of static and dynamic friction on the friction face may
be about 0.3, and may be
about equal to each other, while the coefficients of static and dynamic
friction on the slope face may
be about 0.2, and may be about equal to each other. In either case, whether on
the vertical bearing
face against the sideframe column, or on the sloped face in the bolster
pocket, the present inventors
consider it to be advantageous to avoid surface pairings that may tend to lead
to galling, and stick-slip
behaviour.
Spring Groups
The main spring groups may have a variety of spring layouts. Among various
double damper
embodiments of spring layout are the following:
Di X1 D3 DI Xi D3 DI X1 D3 Di X1 X2 X3 D3
Di X1 X2 D3
X2 X3 X4 X2 X3 X2 X4 X5 X6 X7 X8 D2
X3 X4 D4
r% r%
D2 X5 D4 X4 1-04 D2 X3 D4 D2 X9 X10 XII D4
3 x 3 3:2:3 2:3:2 3 x 5
2 x 4
In these groups, Di represents a damper spring, and Xi represents a non-damper
spring.
In the context of 100 Ton or 110 Ton trucks, the inventors propose spring and
damper
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combinations lying within 20 % (and preferably within 10 %) of the following
parameter envelopes:
(a) For a four wedge arrangement with all steel or iron damper
surfaces, an envelope
having an upper boundary according to __Limper = 2.41(Owedge)1 76, and a lower
boundary according to IL'
_simper = 1 .21(0,edge)1.76
(b) For a
four wedge arrangement with all steel or iron damper surfaces, a mid range
zone of
liclampee = 1.81(Ovvedge)136 (+/- )A0/
(c) For a four wedge arrangement with non-metallic damper surfaces, such as
may be
similar to brake linings, an envelope having an upper boundary according to
lidamper
4.84(0,edge) wedge, 164
1.64, and a lower a lower boundary according to lidampõ = 2.42(0
)
where the wedge angle may lie in the range of 30 to 60 degrees.
(d) For a four wedge arrangement with non-metallic damper surfaces, a mid
range zone
of
lidamper = 3.63(Owedge)1.64 (+1-20 vo).
Where
¨uamper is the side spring stiffness under each damper in lbs/in/damper
wedge- is the associated primary wedge angle, in degrees
wedge may tend to lie in the range of 30 to 60 degrees. In other embodiments
wedge may lie
in the range of 35 ¨ 55 degrees, and in still other embodiments may tend to
lie in the narrower
range of 40 to 50 degrees.
In some embodiments the upward and downward damping forces may be not overly
dissimilar, and may in some cases tend to be roughly equal. Frictional forces
at the dampers may
differ depending on whether the damper is being loaded or unloaded. The angle
of the wedge, the
coefficients of friction, and the springing under the wedges can be varied. A
damper is being
"loaded" when the bolster is moving downward in the sideframe window, since
the spring force is
increasing, and hence the force on the damper is increasing. Similarly, a
damper is being
"unloaded" when the bolster is moving upward toward the top of the sideframe
window, since the
force in the springs is decreasing. The equations can be written as:
While loading: Fd = Fs (Cot (4)) - ILO
(1 + (pi ¨ Pe ) Cot ($) + Ps Pc )
While unloading: Fd = Pc Fs (Cot (4) + ps)
(1 + (ric ¨ ) Cot (4)) ps pc )
Where: Fd = friction force on the sideframe column
F, = force in the spring
tts = coefficient of friction on the angled slope face on the bolster
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= the coefficient of friction against the sideframe column
4. = the included angle between the angled face on the bolster and the
friction face bearing against the column
For a given angle, a friction load factor, Cr can be determined as Cr = Fa /
F. This load
factor Cr will tend to be different depending on whether the bolster is moving
up or down.
In some embodiments there may be spring groups that have different vertical
spring rates
in the empty and fully loaded conditions. To that end springs of different
heights may be
employed, for example, to yield two or more vertical spring rates for the
entire spring group. In
this way, the dynamic response in the light car condition may be different
from the dynamic
response in a fully loaded car, where two spring rates are used.
Alternatively, if three (or more)
spring rates are used, there may be an intermediate dynamic response in a semi-
loaded condition.
In one embodiment, each spring group may have a first combination of springs
that have a free
length of at least a first height, and a second group of springs of which each
spring has a free
length that is less than a second height, the second height being less than
the first height by a
distance 81, such that the first group of springs will have a range of
compression between the first
and second heights in which the spring rate of the group has a first value,
namely the sum of the
spring rates of the first group of springs, and a second range in which the
spring rate of the group
is greater, namely that of the first group plus the spring rate of at least
one of the springs whose
free height is less than the second height. The different spring rate regimes
may yield
corresponding different damping regimes.
For example, in one embodiment a car having a dead sprung weight (i.e., the
weight of the
car body with no lading, and excluding the unsprung weight below the main
springs such as the
sideframes and wheelsets), of about 35,000 to about 55,000 lbs (+/- 5000 lbs)
may have spring
groups of which a first portion of the springs have a free height in excess of
a first height. The
first height may, for example be in the range of about 9¨ 3/4 to 10 ¨1/4
inches. When the car sits,
unladen, on its trucks, the springs compress to that first height. When the
car is operated in the
light car condition, that first portion of springs may tend to determine the
dynamic response of the
car in the vertical bounce, pitch-and-bounce, and side-to-side rocking, and
may influence truck
hunting behaviour. The spring rate in that first regime may be of the order of
12,000 to 22,000
lbs/ in., and may be in the range of 15,000 to 20,000 lbs/in.
When the car is more heavily laden, as for example when the combination of
dead and live
sprung weight exceeds a threshold amount, which may correspond to a per car
amount in the range
of perhaps 60,000 to 100,000 lbs, (that is, 15,000 to 25,000 lbs per spring
group for symmetrical
loading, at rest) the springs may compress to, or past, a second height. That
second height may be
in the range of perhaps 8-V2 to 9-3/4 inches, for example. At this point, the
sprung weight is
sufficient to begin to deflect another portion of the springs in the overall
spring group, which may
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be some or all of the remaining springs, and the spring rate constant of the
combined group of the
now compressed springs in this second regime may tend to be different, and
larger than, the spring
rate in the first regime. For example, this larger spring rate may be in the
range of about 20,000 ¨
30,000 lbs/in., and may be intended to provide a dynamic response when the sum
of the dead and
live loads exceed the regime change threshold amount. This second regime may
range from the
threshold amount to some greater amount, perhaps tending toward an upper
limit, in the case of a
110 Ton truck, of as great as about 130,000 or 135,000 lbs per truck. For a
100 Ton truck this
amount may be 115,000 or 120,000 lbs per truck.
Table 1 gives a tabulation of a number of spring groups that may be employed
in a 100 or
110 Ton truck, in symmetrical 3 x 3 spring layouts and that include dampers in
four-cornered
groups. The last entry in Table 1 is a symmetrical 2:3:2 layout of springs.
The term "side spring"
refers to the spring, or combination of springs, under each of the
individually sprung dampers, and
the term "main spring" referring to the spring, or combination of springs, of
each of the main coil
groups:
Group D7-G1 D7-G2 D7-G3 D7-G4 D7-G5 135-G1
5 * D7-0 5 * D7-0 5 * D7-0 5 * D7-0 5 * D7-0 5 * D5-0
Main Springs 5 * D6-I 5 * D6-I 5 * D8-I 5 * D8-1
5 * D7-I 5 * D6-I
5 * D6A 5 * D6A 5 * D8A 5 * D8A 5 * D8A
4 * B353 4 * B353 4 * NSC-1 4 * B353 4 * B353 4 * B432
Side Springs
---
4 * B354 4 * B354 4 * NSC-2 4 * NSC-2 4 * B433
Group D5-G2 D5-G3 D5-G4 D5-G5 D5-G6 D5-G7
5 * D5-0 5 * D5-0 5 * D5-0 5 * D5-0 5 * D5-0 5 * D5-0
Main Springs 5 * D6-I 5 * D6-I 5 * D8-1 5 * D84 5 * D6-I
5 * D64
5 * D6A 5 * D8A 5 * D6A 5 * D6A
4 * B432 4 * B353 4 * B353 4 * B353 4 * B353 4 * B353
Side Springs
4 * B433 4 * B354 4 * B354 4 * B354 4 * B354 4 * B354
Group D5-G8 D5-G9 D5-G10 135-G11 D5-G12 No. 3
5 * D5-0 5 * D5-0 5 * D5-0 5 * D5-0 5 * D5-0 3 * D51-0
Main Springs 5 * D6-I 5 * D64 5 * D8-I 5 * D84 5 * D5-I 3 * D61-I
5 * D6B 5 * D6A 5 * D8A 5 * D8A 5 * D6B 3 * D61A
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4 *N5C-1 4 *N5C-1 4 * NSC-1 4 * NSC-1 4 * B353 4 * B353-0
Side Springs
4 *NSC-2 4 * B354 4 * B354 4 * NSC-2 4 * NSC-2 4 * B354-I
Table 1 - Spring Group Combinations
In this tabulation, the terms NSC-1, NSC-2, D8, D8A and D6B refer to springs
of non-
standard size. The properties of these springs are given in Table 2a (main
springs) and 2b (side
springs), along with the properties of the other springs of Table 1.
Main Free Rate Solid Free to Solid
Diameter d - Wire
Springs Height Height Solid
Capacity Diameter
(in) (lbs/in) (in) (in) (lbs) (in) (in)
D5 Outer 10.2500 2241.6 6.5625 3.6875
8266 5.500 0.9531
D51 Outer 10.2500 2980.6 6.5625 3.6875
10991 5.500 1.0000
D5 Inner 10.3125 1121.6 6.5625 _ 3.7500
4206 3.3750 0.6250
D6 Inner 9.9375 1395.2 6.5625 3.3750
4709 3.4375 0.6563
D61 Inner 10.1875 1835.9 6.5625 3.6250
6655 3.4375 0.6875
D6A Inner 9.0000 463.7 5.6875 3.3125
1536 2.0000 0.3750
Inner
D61A Inner 10.0000 823.6 6.5625 3.4375
2831 2.0000 0.3750
Inner
.
D7 Outer 10.8125 2033.6 6.5625 4.2500
8643 5.5000 0.9375
D7 Inner 10.7500 980.8 6.5625 4.1875
4107 3.5000 0.6250
D6B Inner 9.7500 575.0 6.5625 3.1875
1833 2.0000 0.3940
Inner
D8 Inner 9.5500 1395.0 6.5625 2.9875
4168 3.4375 0.6563
D8A Inner 9.2000 575.0 6.5625 2.6375
1517 2.0000 0.3940
Inner
Table 2a Main Spring Parameters
Side Springs Free Rate Solid Free to Solid
Coil d - Wire
Height Height Solid Capacity Diameter
Diameter
(in) (lbs/in) (in) (in) (lbs)
(in) (in)
B353 Outer 11.1875 1358.4 6.5625 4.6250 6283 4.8750
0.8125
B354 Inner 11.5000 577.6 6.5625 49375 2852 3.1250
0.5313
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B355 Outer 10.7500 1358.8 6.5625 4.1875
5690 4.8750 0.8125
B356 Inner 10.2500 913.4 6.5625 3.6875 3368
3.1250 0.5625
B432 Outer 11.0625 1030.4 6.5625 4.5000
4637 3.8750 0.6719
B433 Inner 11.3750 459.2 6.5625 4.8125 2210
2.4063 0.4375
49427-1 Outer 11.3125 1359.0 6.5625 4.7500 6455
49427-2 Inner 10.8125 805.0 6.5625 4.2500 3421
B358 Outer 10.7500 1546.0 6.5625 4.1875
6474 5.0000 0.8438
B359 Inner 11.3750 537.5 6.5625 4.8125 2587
3.1875 0.5313
52310-1 Outer 11.3125 855.0 6.5625 4.7500 4061
52310-2 Inner 8.7500 2444.0 6.5625 2.1875 5346
11-1-0562 Outer 12.5625 997.0 6.5625 6.0000 5982
11-1-0563 Outer 12.6875 480.0 6.5625 6.1250 2940
NSC-1 Outer 11.1875 952.0 6.5625 4.6250 4403
4.8750 0.7650
NSC-2 Inner 11.5000 300.0 6.5625 4.9375 1481
3.0350 0.4580
Table 2b - Side Spring Parameters
Table 3 provides a listing of truck parameters that may be used in a number of
trucks, and
for trucks proposed by the present inventors identified as No. 1, No. 2 and
No. 3.
NACO Barber Barber ASF Super ASF No. 1 No. 2
No. 3
Swing S-2-E S-2-HD Service Motion
Motion RideMaster Control
2:3:2
Main 6*D7-0 7*D5-0 6*D5-0 7 * D5-0 7 * D5-0 5 * D5-0 5*D5-0 3*D51-0
Springs 7*D74 7*D5-I 7* D6-I 7 * D5-I 5 * D5-I 5 * D8-I
5*D6-I 3*D61-I
4*D6A 4* D6A 2 * D6A 5 * D8A 5*D6A 3*D61-
A
Side 2*49427- 2*B353 2*B353 2 * 5062 2 * 5062 4*NSC-1 4*B353 4*
B353
Springs 1
2*49427- 2*B354 2*B354 2 * 5063 2 * 5063 4 * B354 4*B354 4*
B354
2
kempty 22414 27414 27088 26496 24253 17326 18952 22194
kloaded 25197 27414 28943 27423 24253 27177 28247 24664
Solid 103,034 105,572 105,347 107,408 96,735 98,773 107,063 97,970
HEmpty 10.3504 9.9898 9.8558 10.0925 10.0721 9.9523 10.0583
10.0707
HLoaded 7.9886 7.9562 7.8748 8.0226 7.7734 7.7181 7.9679 7.8033
4328 3872 3872 2954 2954 6118 7744
7744
kw/kioaded 17.18 14.12 13.38 10.77 12.18 22.51
27.42 31.40
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Wedge a 45 32 32 37.5 37.5 45 40 45
FD (down) 1549 3291 3291 1711 1711 2392 2455
2522
FD (up) 1515 1742 1742 1202 1202 2080 2741
2079
Total FD 3064 5033 5033 2913 2913 4472 5196
4601
Table 3 ¨ Truck Parameters
In Table 3, the Main Spring entry has the format of the quantity of springs,
followed by the
type of spring. For example, the ASF Super Service Ride Master, in one
embodiment, has 7
springs of the D5 Outer type, 7 springs of the D5 Inner type, nested inside
the D5 Outers, and 2
springs of the D6A Inner-Inner type, nested within the D5 Inners of the middle
row (i.e, the row
along the bolster centerline). It also has 2 side springs of the 5052 Outer
type, and 2 springs of the
5063 Inner type nested inside the 5062 Outers. The side springs would be the
middle elements of
the side rows underneath centrally mounted damper wedges.
kempty refers to the overall spring rate of the group in lbs/in for a light
(i.e., empty) car.
kioaded refers to the spring rate of the group in lbs/in., in the fully laded
condition.
"Solid" refers to the limit, in lbs, when the springs are compressed to the
solid condition
HEmpty refers to the height of the springs in the light car condition
HLoaded refers to the height of the springs in the at rest fully loaded
condition
kw refers to the overall spring rate of the springs under the dampers.
kw/kioaded gives the ratio of the spring rate of the springs under the dampers
to the total
spring rate of the group, in the loaded condition, as a percentage.
The wedge angle is the primary angle of the wedge, expressed in degrees.
Fp is the friction force on the sideframe column. It is given in the upward
and downward
directions, with the last row giving the total when the upward and downward
amounts are added together.
In various embodiments of trucks, such as truck 20 or 22, the resilient
interface between
each sideframe and the end of the truck bolster associated therewith may
include a four cornered
damper arrangement and a 3 x 3 spring group having one of the spring groupings
set forth in Table
1. Those groupings may have wedges having primary angles lying in the range of
30 to 60
degrees, or more narrowly in the range of 35 to 55 degrees, more narrowly
still in the range 40 to
50 degrees, or may be chosen from the set of angles of 32, 36, 40 or 45
degrees. The wedges may
have steel surfaces, or may have friction modified surfaces, such as non-
metallic surfaces.
The combination of wedges and side springs may be such as to give a spring
rate under the
side springs that is 20 % or more of the total spring rate of the spring
groups. It may be in the
range of 20 to 30 % of the total spring rate. In some embodiments the
combination of wedges and
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side springs may be such as to give a total friction force for the dampers in
the group, for a fully
laden car, when the bolster is moving downward, that is less than 3000 lbs. In
other embodiments
the arithmetic sum of the upward and downward friction forces of the dampers
in the group is less
than 5500 lbs.
In some embodiments in which steel faced dampers are used, the sum of the
magnitudes of
the upward and downward friction forces may be in the range of 4000 to 5000
lbs. In some
embodiments, the magnitude of the friction force when the bolster is moving
upward may be in
the range of 2/3 to 3/2 of the magnitude of the friction force when the
bolster is moving
downward. In some embodiments, the ratio of Fd(Up)/Fd (Down) may lie in the
range of 3/4 to
5/4. In some embodiments the ratio of Fd(Up)/Fd(Down) may lie in the range of
4/5 to 6/5, and in
some embodiments the magnitudes may be substantially equal.
In some embodiments in which non-metallic friction surfaces are used, the sum
of the
magnitudes of the upward and downward friction force may be in the range of
4000 to 5500 lbs.
In some embodiments, the magnitude of the friction force when the bolster is
moving up, Fd(Up),
to the magnitude of the friction force when the bolster is moving down,
Fd(Down) may be in the
range of 3 /4 to 5/4, may be in the range of 0.85 to 1.15. Further, those
wedges may employ a
secondary angle, and the secondary angle may be in the range of about 5 to 15
degrees.
Nos. 1 and 2
The truck embodiment identified as No. 1 may be taken to employ damper wedges
in a
four-cornered arrangement in which the primary wedge angle is 45 degrees (+/-)
and the damper
wedges have steel on steel bearing surfaces. In the second instance, the truck
embodiment
identified as No. 2, may be taken to employ damper wedges in a four-cornered
arrangement in
which the primary wedge angle is 40 degrees (+0, and the damper wedges have
non-metallic
bearing surfaces. No. 2 may employ non-metallic friction surfaces, that may
tend not to exhibit
stick-slip behaviour, for which the resultant static and dynamic friction
coefficients are
substantially equal. The friction coefficients of the friction face on the
sideframe column may be
about 0.3. The slope surfaces of the wedges may also work on a non-metallic
bearing surface and
may also tend not to exhibit stick slip behaviour. The coefficients of static
and dynamic friction
on the slope face may also be substantially equal, and may be about 0.2. Those
wedges may have
a secondary angle, and that secondary angle may be about 10 degrees.
No. 3
In some embodiments there may be a 2:3:2 spring group layout. In this layout
the damper
springs may be located in a four cornered arrangement in which each pair of
damper springs is not
separated by an intermediate main spring coil, and may sit side-by-side,
whether the dampers are
cheek-to-cheek or separated by a partition or intervening block. There may be
three main spring
coils, arranged on the longitudinal centreline of the bolster. The springs may
be non-standard
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springs, and may include outer, inner, and inner-inner springs identified
respectively as D51-0,
D61-I, and D61-A in Tables 1,2 and 3 above. The No. 3 layout may include
wedges that have a
steel-on-steel friction interface in which the kinematic friction co-efficient
on the vertical face may
be in the range of 0.30 to 0.40, and may be about 0.38, and the kinematic
friction co-efficient on
the slope face may be in the range of 0.12 to 0.20, and may be about 0.15. The
wedge angle may
be in the range of 45 to 60 degrees, and may be about 50 to 55 degrees. In the
event that 50 (+/-)
degree wedges are chosen, the upward and downward friction forces may be about
equal (i.e.,
within about 10 % of the mean), and may have a sum in the range of about 4600
to about 4800 lbs,
which sum may be about 4700 lbs (+/- 50). In the event that 55 degree (+/-)
wedges are chosen,
the upward and downward friction forces may again be substantially equal
(within 10 % of the
mean), and may have a sum on the range of 3700 to 4100 Lbs, which sum may be
about 3850 ¨
3900 lbs.
Alternatively, in other embodiments employing a 2:3:2 spring layout, non-
metallic wedges
(i.e., wedges having non-metallic friction linings, pads or coatings,
typically mounted to a cast
iron or steel damper wedge body) may be employed. Those wedges may have a
vertical face to
sideframe column co-efficient of kinematic friction in the range of 0.25 to
0.35, and which may be
about 0.30. The slope face co-efficient of kinematic friction may be in the
range of 0.08 to 0.15,
and may be about 0.10. A wedge angle of between about 35 and about 50 degrees
may be
employed. It may be that the wedge angles lie in the range of about 40 to
about 45 degrees. In
one embodiment in which the wedge angle is about 40 degrees, the upward and
downward
kinematic friction forces may have magnitudes that are each within about 20 %
of their average
value, and whose sum may lie in the range of about 5400 to about 5800 lbs, and
which may be
about 5600 lbs (+/- 100). In another embodiment in which the wedge angle is
about 45 degrees,
the magnitudes of each of the upward and downward forces of kinematic friction
may be within
20 % of their averaged value, and whose sum may lie in the range of about 440
to about 4800 lbs,
and may be about 4600 lbs (+/- 100).
Combinations and Permutations
The present description recites many examples of dampers and bearing adapter
arrangements. Not all of the features need be present at one time, and various
optional
combinations can be made. As such, the features of the embodiments of several
of the various
figures may be mixed and matched, without departing from the spirit or scope
of the invention.
For the purpose of avoiding redundant description, it will be understood that
the various damper
configurations can be used with spring groups of a 2 X 4, 3 X 3, 3:2:3, 2:3:2,
3 X 5 or other
arrangement. Similarly, several variations of bearing to pedestal seat adapter
interface
arrangements have been described and illustrated. There are a large number of
possible
combinations and permutations of damper arrangements and bearing adapter
arrangements. In
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that light, it may be understood that the various features can be combined,
without further
multiplication of drawings and description.
The various embodiments described herein may employ self-steering apparatus in
combination with dampers that may tend to exhibit little or no stick-slip
behaviour. They may
employ a "Pennsy" pad, or other elastomeric pad arrangement, for providing
self-steering.
Alternatively, they may employ a bi-directional rocking apparatus, which may
include a rocker
having a bearing surface formed on a compound curve of which several examples
have been
illustrated and described herein. Further still, the various embodiments
described herein may
employ a four cornered damper wedge arrangement, which may include bearing
surfaces of a non-
stick-slip nature, in combination with a self steering apparatus, and in
particular a bi-directional
rocking self-steering apparatus, such as a compound curved rocker.
In the various embodiments of trucks herein, the gibs may be shown mounted to
the bolster
inboard and outboard of the wear plates on the side frame columns. In some of
the embodiments
the clearance between the bolster gibs and the side frames may be sufficient
to permit a motion
allowance of at least 3/4" of lateral travel of the truck bolster relative to
the wheels to either side of
neutral, advantageously permits greater than 1 inch of travel to either side
of neutral, and may
permit travel in the range of about 1 or 1 ¨ 1/8" to about 1 ¨ 5/8 or 1 ¨
9/16" inches to either side
of neutral.
In one embodiment there may be a combination of a bi-directional compound
curvature
rocker surface, a four cornered damper arrangement in which the dampers are
provided with friction
linings that may tend to exhibit little or no stick-slip behaviour, and may
have a slope face with a
relatively low friction bearing surface. However, there are many possible
combinations and
permutations of the features of the examples shown herein. In general it is
thought that a self
draining geometry may be preferable over one in which a hollow is formed and
for which a drain hole
may be required.
In each of the trucks shown and described herein, the overall ride quality may
depend on
the inter-relation of the spring group layout and physical properties, or the
damper layout and
properties, or both, in combination with the dynamic properties of the bearing
adapter to pedestal
seat interface assembly. The lateral stiffness of the sideframe acting as a
pendulum may be less
than the lateral stiffness of the spring group in shear. In rail road cars
having 110 ton trucks, one
embodiment may employ trucks having vertical spring group stiffnesses in the
range of 16,000
lbs/inch to 36,000 lbs/inch in combination with an embodiment of bi-
directional bearing adapter to
pedestal seat interface assemblies as shown and described herein. In another
embodiment, the
vertical stiffness of the spring group may be less than 12,000 lbs./in per
spring group, with a
horizontal shear stiffness of less than 6000 lbs./in.
The double damper arrangements shown above can also be varied to include any
of the
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four types of damper installation indicated at page 715 in the 1997 Car and
Locomotive
Cyclopedia, with appropriate structural changes for doubled dampers, with each
damper being
sprung on an individual spring. That is, while inclined surface bolster
pockets and inclined
wedges seated on the main springs have been shown and described, the friction
blocks could be
in a horizontal, spring biased installation in a pocket in the bolster itself,
and seated on
independent springs rather than the main springs. Alternatively, it is
possible to mount friction
wedges in the sideframes, in either an upward orientation or a downward
orientation.
The embodiments of trucks shown and described herein may vary in their
suitability for
different types of service. Truck performance can vary significantly based on
the loading
expected, the wheelbase, spring stiffnesses, spring layout, pendulum geometry,
damper layout
and damper geometry.
Various embodiments of the invention have been described in detail. Since
changes in and
or additions to the above-described best mode may be made without departing
from the nature,
spirit or scope of the invention, the invention is not to be limited to those
details but only by the
appended claims.
