Note: Descriptions are shown in the official language in which they were submitted.
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RAIL ROAD CAR TRUCK AND BEARING ADAPTER FITTINGS THEREFOR
Field of the Invention
This invention relates to the field of rail road cars, and, more particularly,
to the field of
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 axles, 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 improving 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
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and may tend to reduce wear to both the wheels and the track, and may give a
smoother overall
ride.
Another issue which may arise may pertain to peak loading in the rollers of
the bearings.
It is thought that the life of bearing components may be strongly related to
the maximum cyclic
load. In some instances, the cyclic load may reach a maximum when the
uppennost roller in a
bearing race is at the top center position, with a steep drop off to either
side of the topmost roller.
It may be desirable to spread this loading in an effort to moderate the peak
loading as the rollers
pass through the top center position.
Summary of the Invention
In an aspect of the present invention there may be a bearing adapter to
sideframe
interface assembly for use in a railroad car truck. The interface assembly may
include a bearing
adapter and an elastomeric pad mounted thereon, said bearing adapter having a
body having first
and second arches for mating with a bearing of a rail road car wheelset, those
arches being
axially spaced apart to engage opposite ends of the bearing with the bearing
races located axially
therebetween, the arches having apices that, when installed in an at rest
condition on the bearing,
are axially aligned centrally over the bearing. The body of the bearing
adapter has a central
portion inteimediate said arches, that central portion having a bearing shell
engagement interface
formed to seat about a portion of the circumference of the bearing shell. One
of the bearing
adapter and the elastomeric pad has a relieved portion axially aligned with
the apices of the
arches.
In an aspect of the invention there is a rail road car truck which has first
and second
spaced apart wheelsets, with first and second sideframes mounted to the
wheelsets. There is also
attached a bolster resiliently mounted cross-wise between the sideframes with
each of the
sideframes having a sideframe pedestal mounting at either end thereof Each of
the wheelsets
including an axle having two ends and each of the axles having bearings
mounted to either end
thereof The fittings defining a bearing to sideframe pedestal mounting
assembly, and the
assembly providing a load path for vertical loads between the sideframe
pedestal mounting, and
the bearing and the assembly having a vertical load path discontinuity and the
discontinuity
being located above top dead center of the bearing.
In a feature, the truck is a Barber S2HD rail road car truck. There is also a
feature which
consists of the assembly and includes a bearing adapter and a resilient member
mounted between
the bearing adapter and the pedestal mounting, and the bearing adapter has a
laterally extending
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relief formed therein, the relief being located over top dead center of at
least one bearing race of
the bearing. In another feature, the assembly with a bearing adapter and a
resilient member are
mounted between the bearing adapter and the pedestal mounting. The bearing
adapter has a
downwardly facing interface matingly engaged with the bearing, and the
downwardly facing
interface includes a relief located over top dead center of at least one
bearing race of the bearing,
and the relief defines the vertical load path discontinuity.
In another feature, the assembly includes a bearing adapter and a resilient
member which
is mounted between the bearing adapter and the pedestal mounting. The bearing
adapter has an
upwardly facing interface matingly engaged with the resilient member, and the
bearing adapter
has a relief foimed in the upwardly facing interface. The relief being located
over top dead center
of a bearing race of the bearing. The resilient member has a region of non-
homogeneity and the
region of non-homogeneity being located over top dead center of at least one
bearing race of the
bearing, and the non-homogeneity defining the discontinuity of the load path.
However, the
resilient member has a relief formed therein and the relief being located over
top dead center of
at least one bearing race of the bearing, and the non-homogeneity defining the
discontinuity of
the load path.
In an additional feature, the assembly includes a bearing adapter and a pair
of resilient
pads mounted to be squeezed vertically between the bearing adapter and the
pedestal mount. The
pads are spaced apart by a gap, and the gap being located over top dead center
of at least, one
bearing race of the bearing. In another feature, the assembly includes a
bearing adapter and a
resilient pad mounted over the bearing adapter, and a pedestal seat member
mounted over the
resilient pad. The pedestal seat member being mounted in the pedestal mount,
and the pedestal
seat having a relief defined therein, the relief being located over top dead
center of the bearing.
In another feature, the truck has friction dampers mounted between the bolster
and the
sideframes. The friction dampers work on a friction interface that includes a
non-metallic
friction member. Also in a further feature, the sideframes each have a
sideframe window defined
between a pair of sideframe columns, and the non-metallic friction member is
mounted to one of
the sideframe columns. The friction dampers present a surface to the non-
metallic member, and
the surface is made from a material chosen from the set of materials
consisting of (a) cast iron
(b) steel; and (c) an iron based alloy other than a steel.
In another feature, the bolster has two ends, one of each ends being mounted
to each of
the sideframes, and the bolster has four independently sprung friction dampers
mounted at each
end thereof
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In another feature, the assembly includes a bearing adapter and a resilient
member
mounted over the bearing adapter. The resilient member bears against the
pedestal mount and
the bearing adapter having an upper surface having a central region lying
between a pair of
spaced apart side regions, the side regions having upper surfaces standing
upwardly proud of the
central region, the spaced apart regions having a crown radius, and the
resilient member seating
over the crown radius. In another feature the assembly is free of any rocker
member located
above the resilient member.
Illustrations in the Application
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.
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 lc shows a side view of the railroad car truck of Figure la;
Figure id shows an exploded view of a portion of a truck similar to that of
Figure la;
Figure le is an exploded 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 a sideframe such as might be employed in
an
embodiment of the railroad car truck of Figure la;
Figure lg shows a side view of the sideframe of Figure if;
Figure lh shows a top view of the sideframe of Figure if;
Figure li shows a view looking along the longitudinal axis of the sideframe
toward the
sideframe column, taken on ii ¨ li' in Figure lg,
Figure lj shows an alternate arrangement to that of Figure li;
Figure 2 shows an alternate bolster, generally similar to that shown in Figure
id, with a
pair of spaced apart bolster pockets, having inserts and wedges with primary
and
secondary angles;
Figure 3a is a front view of a friction damper for a truck such as that of
Figure la;
Figure 3b shows a side view of the damper of Figure 3a;
Figure 3c shows a rear view of the damper of Figure 3b;
Figure 3d shows a top view of the damper of Figure 3a;
Figure 3e shows a cross-sectional view on the centerline of the damper of
Figure 3a
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taken on section '3e ¨ 3e' of Figure 3c;
Figure 3f is a section of the damper of Figure 3a taken on section 3f¨'
3f' of Figure 3e;
Figure 3g shows an isometric view of an alternate damper to that of Figure 3a
having a
friction modifying side face pad;
Figure 3h shows an isometric view of a further alternate damper to that of
Figure 3a,
having a "wrap-around" friction modifying pad;
Figure 4a is an exploded isometric view from above, in front, and to one side
of a
bearing, bearing adapter and elastomeric pad assembly for use in the truck of
Figure
la;
Figure 4b shows a cross section of the assembly of Figure 4a, as assembled,
taken in the
vertical plane of the longitudinal axis of the bearing;
Figure 4c is a half end view, half section view of the assembly of Figure 4a,
as viewed
looking along the long axis of the bearing, the half section being a view on
section
`4c- 4c' of Figure 4b;
Figure 4d is an underside isometric view of the bearing adapter and pad of
Figure 4a;
Figure 4e is a bottom view of the bearing adapter and elastomeric pad of
Figure 4a;
Figure 4f is a longitudinal section of the bearing adapter and elastomeric pad
of Figure
4e taken on section '4f- 4f' of Figure 4e;
Figure 4g is a lateral section of the bearing adapter and elastomeric pad of
Figure 4e
taken on the central plane of symmetry, indicated as '4g ¨ 4g' in Figure 4e;
Figure 5a shows an exploded underside isometric view of an alternate
combination of
bearing adapter and elastomeric pad to that of the assembly of Figure 4a;
Figure 5b shows a bottom view of the bearing adapter and elastomeric pad of
Figure 5a;
Figure 5c shows a longitudinal cross-section of the bearing adapter and
elastomeric pad
of Figure 5a, as assembled, taken on the central, longitudinal axis of
symmetry
indicated as `5c ¨ 5c' in Figure 5b;
Figure 5d shows a lateral cross-section of the bearing adapter and elastomeric
pad of
Figure 5a, as assembled, taken on the central lateral plane of symmetry,
indicated as
'5d ¨ 5d' in Figure 5b;
Figure 6a is an exploded isometric view from above, in front, and to one side
of an
alternate bearing adapter and pad assembly to that of Figure 4a;
Figure 6b shows an underside isometric view of the assembly of Figure 6a;
Figure 6c shows a longitudinal cross section on the central plane of symmetry
of the
assembly of Figure 6a, as assembled taken on section '6c ¨ 6c' of Figure 6a;
Figure 6d is a longitudinal section on the central plane of symmetry of the
bearing
adapter and pad of Figure 6a, as assembled, taken on section '6d ¨ 6d' of
Figure 6a;
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Figure 7a shows a top view of alternate bearing adapter to that of Figure 6a
having a pair
of reliefs formed in a central region of the upper portion thereof
Figure 7b shows a longitudinal cross-sectional view of the bearing adapter of
Figure 7a
taken on section `b ¨ 7b' through on of the reliefs as indicated in Figure 7c;
Figure 7c shows a lateral cross-sectional view on the central plane of
symmetry of the
bearing adapter of Figure 7a, indicated as section lc ¨ 7c' in Figure 7b;
Figure 8a shows an isometric exploded view, from above, of an alternate
embodiment of
bearing adapter and pad combination to that of Figure 4a in which the
underside of
the pad has a laterally extending slot in a central region thereof;
Figure 8b shows an isometric view, from below, of the bearing adapter and pad
combination of Figure 8a;
Figure 8c shows a longitudinal cross-section of the bearing adapter pad of
Figure 8b
viewed on the central plane of symmetry;
Figure 8d shows a lateral cross-section of the bearing adapter pad of Figure
8b as viewed
on the central plane of symmetry;
Figure 8e is an isometric view, from above, of an alternate pad to that of
Figure 8b in
which the top of the pad has a slot extending laterally across a central
region thereof;
Figure 8f shows a cross-section of the alternate pad of Figure 8e taken on the
longitudinal plane of symmetry thereof;
Figure 8g shows a section on the longitudinal plane of symmetry of an
alternate pad to
that of Figure 8a having an array of internal hollows within a central portion
thereof;
Figure 8h shows a section on the lateral plane of symmetry of the pad of
Figure 8g;
Figure 8i shows an isometric view of an alternate bearing adapter and pad
combination
to that of Figure 8a; employing a pair of pads having a central gap
therebetween;
Figure 8j shows an isometric view from below of the bearing adapter of Figure
Si;
Figure 9a shows an isometric underside view of an alternate pad and bearing
adapter
combination to that of Figure 8a; in which the underside of the pad has
reliefs;
Figure 9b shows an isometric view, from above, of an alternate bearing adapter
and pad
combination to that of Figure 8a having reliefs on the upper side of the pad;
Figure 9c shows a view similar to Figure 9a, but of an alternate pad wherein
the pad has
reliefs extending fully therethrough;
Figure 10a shows an isometric view from above of an alternate bearing adapter
and pad
combination to that of Figure 8a, having an array of longitudinally extending
slots;
Figure 10b shows an underside isometric view of the bearing adapter and pad
combination of Figure 10a;
Figure 10c shows a section on the lateral plane of symmetry of the pad of
Figure 10a;
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Figure 10d shows a lateral cross-section of an alternate pad to that of Figure
10c;
Figure 10e shows a lateral cross-section of an alternate pad to that of Figure
10c;
Figure 10f shows an isometric view from above of an alternate pad to that of
Figure 8a;
having a central portion of a different resiliency than the end portions;
Figure lOg shows an isometric view from above of an alternate bearing adapter
and pad
combination to that of Figure 8a in which the pad has a perforated medial
portion;
Figure ha shows an exploded isometric view from above of an alternate bearing
adapter, pad and pedestal seat assembly to that of Figure 8a;
Figure llb shows a side view of a pedestal seat member for the assembly of
Figure 11a;
Figure 11c shows an isometric view, from above, of an alternate pedestal seat
member to
that of Figure 11b;
Figure lid shows a top view of the pedestal seat member of Figure 11c;
Figure lie shows a side view of the pedestal seat member of Figure 11c;
Figure 12a shows an exploded isometric view, from above, of an alternate
combination
of bearing adapter and pad to that of Figure 4a;
Figure 12b shows an exploded isometric view, from below, of an alternate
combination
of bearing adapter and pad to that of Figure 4a;
Figure 12c is a section on the central, lateral plane of symmetry of the pad
of Figure 12a;
Figure 12d shows a section of an alternate bearing adapter and pad combination
to that
of Figure 12a at the lateral plane of symmetry thereof, as installed in a
pedestal seat;
Figure 12e shows a section of the bearing adapter and pad combination of
Figure 12d on
the longitudinal plane of symmetry thereof;
Figure 13a is a half end view, half section view of the assembly of Figure
13b, as viewed
looking along the long axis of the bearing, the half section being a view on
section
'13a ¨ 13a' of Figure 13b; and
Figure 13b shows a cross-section on a longitudinal plane of symmetry of an
integrated
bearing, bearing adapter pad.
Detailed Description
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, or
similar parts to which the same nomenclature may be applied, are marked
throughout the
specification and the drawings with the same respective reference numerals.
The drawings are
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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 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 (GWR) 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. GWR 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 /997 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
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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 of the 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
equalization. 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 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 13 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 13 may tend to urge the damper either
inboard or outboard
according to the angle chosen.
Figure la shows an example of a three piece truck 22 such as might most
commonly be
installed under a railroad freight car body. Truck 22 may have a 3 x 3, 3:2:3,
5 x 3, 2 x 4, 2:3:2
or other suitable spring group arrangement, and is intended to be generically
representative in
this regard without need for multiple illustrations of truck variations. Truck
22 may be suitable
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for a variety of general purpose uses, which may include carrying relatively
low density, high
value lading, such as automobiles or consumer products, or for carrying denser
semi-finished
industrial goods, such as might be carried in rail road freight cars for
transporting rolls of paper,
or for carrying bulk commodities such as grain, plastic pellets, potash, ores,
or coal. Truck 22 is
intended to be illustrative of a wide range of truck types. Truck 22 is
symmetrical about both the
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 22 has a truck bolster 24 and sideframes 26. Each sideframe 26 has a
generally
rectangular window 28 that accommodates one of the ends 30 of bolster 24. The
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 seat. This upper
fitting, is indicated
generically as 40. Fitting 40 may engage a mating fitting 42 mounted to the
upper surface of a
bearing adapter 44. Fitting 42 may be a resilient member, and may be an
elastomeric member
such as, or similar to a -Pennsy" pad, that may deflect longitudinally in
shear during operation to
give a measure of self-steering capability to truck 22. 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.
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. Several different embodiments of
this wheelset to
sideframe interface assembly are described below. 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,
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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 34 of sideframe 26 may have a basket plate,
or
lower spring seat 52 rigidly mounted thereto. 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 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 may have 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.
This arrangement may be referred to as a -double damper" arrangement in which
a pair of
laterally spaced dampers works against each sideframe column, in contrast to
the arrangement of
Figure le, which shows a single damper arrangement, namely a single damper
acting against
each sideframe column. This arrangement of Figure id may also be referred to
as a "four
cornered" damper arrangement, since there are four dampers at each end of the
bolster, those
four dampers being arranged in a rectangular manner.
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.
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The bearing plate, namely sideframe column wear plate 92 (Figure la) may be
significantly wider than the through thickness of the sideframes more
generally, as measured, for
example, at the pedestals, and may 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. 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
travel to either side. Bolster 24 has inboard and outboard gibs 106, 108
respectively, that bound
the lateral motion of bolster 24 relative to sideframe columns 36.
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 if¨ lj
Figures if to lj pertain to an embodiment of sideframe such as may be used in
truck 22.
The friction damper elements, often damper wedges, mounted in the bolster
pockets may be
made of iron or steel, and may not necessarily have non-metallic wear members.
In one
embodiment where cast iron or steel wedges are used, with cast iron or steel
friction faces
oriented to face toward, and to work against, the sideframe columns, a
sideframe 120 may
include sideframe columns 122, 124 on either side of the sideframe window 28.
Those sideframe
columns may support a wear plate backing member, or backing frame 126. Backing
frame 126
may have angled gusset reinforcement, and internal web reinforcements outside
and inside the
sideframe castings. A wear plate member 130 may be mounted to backing frame
126. Wear
plate 130 may have countersunk bores, as at 132, by which fasteners may be
introduced to mount
wear plate 130 in place. Wear plate 130 may be made of an iron or steel member
for working
against a non-metallic shoe, or wear member of an opposed damper.
Alternatively, wear plate
130 may be a non-metallic friction member, akin to a brake shoe or clutch
lining, such as may be
replaced from time to time when worn. In one embodiment, wear plate 130 may be
made of, or
faced with, a non-metallic wear material having a tendency not to exhibit
stick slip behaviour
when working in co-operation with steel or iron faced dampers. Wear member 130
may have
dynamic and static co-efficients of friction that are, or are substantially,
the same. Those co-
CA 02490924 2012-08-13
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efficients of friction may be in the range of 0.15 to 0.35, and may be about
0.20 (+/- 20 %) or
may be about 0.30 (+/- 20%)
In one embodiment, illustrated in Figure 1j, sideframe 120 has a dual wear
plate
mounting, where left and right hand wear plate portions 134 and 136 are
mounted side-by-side
by mechanical fasteners to the sideframe column.
In either Figure if or Figure 1j, the frontal area of the non-metallic member
may exceed,
and may substantially exceed, the surface area of the steel or cast iron
member working against
it. For example, in one embodiment, the area of the non-metallic friction wear
member mounted
to the sideframe column is more than twice as great as the working surface of
the front face of
the co-operable damper wedge.
Figure le
Figure le shows an example of an alternate three piece railroad car truck,
shown generally
as 250. Truck 250 has a truck bolster 252, and a pair of sideframes 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.
Figure 2
Damper wedges with only primary wedge angles may be used, whether in the truck
of
Figure la or Figure le. However, in some embodiments a truck such as truck 22
may employ
CA 02490924 2012-08-13
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wedges having both primary wedge angles and secondary wedge angles. Figure 2
shows an
isometric view of an end portion of a truck bolster 210 such as might be used
in truck 22 of
Figure la. 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.
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
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
ariii 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
illustrated in the example embodiment of Figure 5a, with or without wear
inserts.
CA 02490924 2012-08-13
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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.
Figures 3a ¨ 3h
Referring to Figures 3a ¨ 3e, a damper, which may be in the fo _____ -in of a
damper wedge 310
is shown such as may be used in truck 22, or any other double damper truck
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 3a ¨ 3e 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.
Damper 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.
Alternatively, damper
wedge 310 may have steel or cast iron wear plates for member 316, or may
dispense with a wear
plate insert, and may employ a monolithic steel or cast iron wedge. Such a
wedge may work
against a non-metallic wear plate member mounted to the sideframe column, as
described in the
context of Figures if to 1 j herein.
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 fon-ned
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
CA 02490924 2012-08-13
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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 portion
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 of
junction, 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 dynamic friction may be
substantially equal, may be
about 0.2 (+/- 20 %, or, more narrowly +/- 10%), and may be substantially free
of stick-slip
behaviour.
In the alternative embodiment of Figure 3g, 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 sideframe 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 3h, 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.
In this embodiment, vertical face 268 of friction damper 264, 266 may have a
bearing
surface having a co-efficient of static friction, Its, and a co-efficient of
dynamic or kinetic friction,
f.tk, 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
CA 02490924 2012-08-13
- 18 -
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 3a
¨ 3h. 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
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 4a ¨ 4f
Figure 4a shows an arrangement of bearing to sideframe interface assembly that
may be
employed in the trucks of Figures la and le. In the wheelset to sideframe
interface assembly of
Figure 4a, indicated generally as 340, a bearing adapter 44 may be employed
with a fitting such
as resilient member 42 that may be in the nature of an elastomeric pad
identified as resilient
member 342, such as may be a "Pennsy pad". 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. Bearing adapter 44 may have an upper surface 344 that
provides a cradle, or
seat, for pad 342. The upper portion of bearing adapter 44 may include a
central bed portion
346. Bed portion 346 may lie between a pair of lateral indexing features, such
as may be in the
nature of longitudinally extending channels, or grooves or depressions, 348,
350. A pair of
raised, longitudinally extending lateral retainer members, or lateral abutment
walls, or side walls
352, 354 may stand upwardly of channels 348 and 350, and may thereby bracket
both channels
348, 350 and bed portion 346. At either longitudinal end of bed 346 there may
be longitudinal
indexing or retainer fittings, such as may be in the nature of laterally
extending depressions 356,
358.
Pad 342 may have a lower surface 360, that is foinied to engage the top of the
bearing
adapter in a manner inhibit migration or displacement of pad 342 relative to
the bearing adapter.
For example, pad 342 may have the negative image of bed 346, with lateral
indexing members,
such as may be in the nature of longitudinally extending rails, or feet, 362,
364 that seat in
mating engagement in channels 348 and 350 in close fitting location between
sidewalls 352, 354,
and which may tend to bound lateral deflection or migration of pad 342. Pad
342 may also have
CA 02490924 2012-08-13
- 19 -
longitudinal indexing, or keying, or retaining features such as may be in the
nature of blisters, or
bulges, 366, 368 that seat in mating engagement in depressions 356, 358 and
may tend to inhibit
longitudinal migration of pad 342 relative to bearing adapter 44. Pad 342 may
also have, at its
end regions, depending legs, or feet, 370, 372 and end wall members, such as
may be identified
as skirts 374, such as may extend laterally between feet 370 and 372 and
which, when installed,
may depend downwardly over a portion, or all of, end walls 376 of bearing
adapter 44. Bearing
adapter 44 may have a three sided shelf or ridge, 380 running about the inside
of legs 370, 372
and wall 376 in a manner to which the depending toes of feet 370, 372 and
lower edge of skirt
374 may conform. Pad 342 may also include an upper surface, 382, for mating
engagement with
the pedestal seat fitting, such as may be a wear liner seated in the pedestal
roof, or the pedestal
roof, as may be.
Pad 342 may be a single resilient member 384, 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
384 has first and
second end portions 386, 388 for interposition between the thrust lugs of the
jaws of the pedestal
and the ends 390 and 391 of the bearing adapter. End portions 386, 388 may
tend to be a bit
undersize so that 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.
The pad, namely resilient member 342 may also have a central or medial portion
394
extending between end portions 386, 388. Medial portion 394 may extend
generally horizontally
inward to overlie substantial portions, if not substantially all, of the upper
surface bearing
adapter 44. In one embodiment the resilient member 342 may be formed in the
manner of a
Pennsy Pad. Figure 4a shows an installation thereof The Pennsy pad may tend to
permit a
measure of passive steering. The Pennsy pad installation of Figures 4a ¨ 4d
may be installed in
the sideframe of Figure la, in combination with a four cornered damper
arrangement, as
indicated in Figures la ¨ id or in the single damper arrangement of Figure le.
For example, in
one embodiment, the truck of Figure le may be taken as being a Barber S2HD
truck. In another
embodiment, the truck of Figure la may be taken to be a Barber S2HD truck
modified to carry a
four-cornered damper arrangement, as described above.
In the embodiments described herein, the resilient member, which may be an
elastomer,
and may be a man made polymer having an elastic response, is assumed to be in
extensive
CA 02490924 2012-08-13
- 20 -
surface contact with both an underlying member, in the nature of the interface
with the
underlying bearing adapter, and in extensive surface contact with an overlying
member, such as
a pedestal seat, or, in some instances, with the pedestal roof itself where no
intermediate member
is employed. In each case the resilient member is understood to be squeezed
bodily between
these two interfaces, and to transmit the vertical load imposed during normal
operation. That is,
the resilient member is expected to transmit a vertical load that is imposed
in a direction through
the thickness of the material.
In this example, and in the other examples discussed below, the gap foinied
(or, in some
examples below, the non-homogenous vertical response created by having regions
of different
vertical stiffness) may tend to yield a vertical load path discontinuity. This
vertical load path
discontinuity may tend to cause the vertical loads from the sideframe pedestal
to be passed into
the bearing in a manner in which the vertical load is shed, or shared,
laterally to a greater extent
than might be the case but for that discontinuity. This load shedding, or
sharing, to either side of
top dead center of the bearing races may tend to increase roller loading away
from top dead
center, and reduce, or moderate it at top dead center. The extent to which
this load shedding or
load sharing may occur may be greater, or lesser depending on the geometry
chosen. It may be
that the geometry is chosen to maintain a gap at all times, including under
the most extreme
vertical design load. Alternatively, it may be chosen to maintain a gap at the
mean loading of the
bearing races when the truck is carrying its full rated load, be it half a
263,000 lb car, half a
286,000 lb car or half a 315,000 lb car. Alternatively, it may be chosen to
maintain a gap at the
mean loading plus one, two or three standard deviations from the mean loading,
based on
recorded load histories. This type of bearing adapter and pad arrangement, or
the other
embodiments described hereinbelow is not necessarily limited to four wheeled
trucks, such as
three piece freight car trucks, for example, but may also be used in a six
wheeled truck or an
eight wheeled truck, or other truck.
Figures 4c ¨ 4f
The illustrations of Figures 4b and 4c include illustrations of bearing 46
that 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. Bearing 46 may be 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 may be held in place by
an end cap 766
mounted to the end of axle 752. Figures 4b and 4c are provided, in part, to
illustrate the location of
CA 02490924 2012-08-13
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the bearing adapter arches 114, 116, relative to the bearing casing or outer
ring member 764, those
arches lying in generally parallel planes and being spaced in the axial
direction of the bearing
sufficiently far apart to bracket the casing, such that the body of the
bearing adapter, namely the
central portion between the two arches, overspans, and brackets or straddles,
the bearing races. That
is, the bearing races lie axially between the two end arches. As can be seen
in the end cross-section,
the apex of the arches, and the center, or central portion, of the body of the
bearing adapter, in the
centered, at-rest position, may tend to lie directly above the uppermost
rollers of the bearing races.
Figures 4e ¨ 4g
Figures 4e ¨ 4g show views of bearing adapter 44, having underside grooving,
392 in the
nature of a pair of laterally extending tapered lobate depressions, cavities,
rebates, or reliefs 395,
396 separated by a central bridge region 398 having a deeper section and
flanks that taper into
reliefs 395, 396. Reliefs 395, 396 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. This major axis may lie at the apex of the under side of
bearing adapter 44,
parallel to the axis of rotation of bearing 46. The absence of material at
reliefs 395, 396 may
tend to leave a generally H-shaped footprint on the circumferential surface
400 that seats upon
the outside of bearing 46, in which the two side regions, or legs, of the H
form lands or pads 402,
404 joined by a relatively narrow waist, namely bridge region 398. To the
extent that the
undersurface of the lower portion of bearing adapter 44 conforms to an arcuate
profile, such as
may accommodate the bearing casing, reliefs 395, 396 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 sideframe pedestal load into pads 402,
404 and thence into
bearing 46. By leaving a space between the underside of the bearing adapter
and the top center
of the bearing casing over the bearing races, reliefs 395, 396 may tend to
prevent the vertical
load being passed in a concentrated manner predominantly into the top rollers
in the bearing.
Instead, it may perhaps tend to be spread between several rollers in each race
somewhat more or
less evenly, than might otherwise be the case. Central bridge region 398 may
seat above a
section of the bearing casing under which there is no race, rather than
directly over one of the
races. Conversely, reliefs 394, 396 may seat over top center position of the
rollers in the bearing
races, tending to cause the load to be passed into the bearing casing to
either side of the top
roller. It is thought that this may tend to encourage longer bearing life. The
width of each of
reliefs 394, 396 may be taken, on a circumferential arc measurement, to be
wider than the width
of a roller. Inasmuch as there may be roughly 23 rollers in the bearing,
rebate 392, may be
larger, or wider, than 15 degrees of arc as measured from the center of
rotation of the bearing.
CA 02490924 2012-08-13
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Figures 5a ¨ 5d
Figures 5a ¨ 5d show an alternate combination of a bearing adapter 410 and
resilient
member, or pad, 412 to that described above. Pad 412 may be identical to
resilient member 342.
The underside of bearing adapter 410 may have a circumferentially extending
medial
groove, channel or rebate 414, having an apex lying on the transverse plane of
symmetry of
bearing adapter 410, but also a laterally extending underside groove, channel,
slot or rebate 416
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 410 has
four corner lands or pads 418 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 casing of the bearing.
Rebate 416 may
tend to lie along the apex of the arch of the underside of bearing adapter
410. Rebates 414 and
416 may intersect as shown, form a cross. Rebate 416 may be relatively the
shallower, and may
be gently radiused into the surrounding bearing adapter body. The body of
bearing adapter 410
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 416 may tend to lie at the
section of minimum
cross-sectional area of bearing adapter 410. Rebates 414 and 416 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 the
bearing than might
otherwise be the case. As before in one embodiment, the width of rebate 416
may correspond
roughly to the width of one roller.
Figures 6a - 6d
Figures 6a to 6d show an alternate combination of bearing adapter and
resilient pad
member to that of Figures 4a or 5a. In Figure 6a, a bearing adapter is
identified as 420. The
resilient pad may be taken as being the same as resilient member 342 described
above.
Bearing adapter 420 may have a circumferentially extending groove 422 formed
therein,
which may be generally similar to rebate 414 of bearing adapter 410. However,
rather than
having an underside lateral groove, bearing adapter 420 may have a topside
that is the same as,
or substantially similar to that of bearing adapter 44, except insofar as it
has a lateral relief,
CA 02490924 2012-08-13
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groove, slot, rebate or channel 424 that may be centered over, and may run
parallel to, the axis of
rotation of bearing 46. Channel 424 may tend to separate the upper surface of
the bed of bearing
adapter 420 into two regions 426 and 428. The transition from regions 426 and
428 into channel
424 may be on relatively large radii, and the walls of channel 424 may be
inclined, or chamfered
as well. In one embodiment, the depth of channel 424 may be of the order of
1/3 to 1/8 of its
overall width. The width of channel 424 may correspond to about the arc of one
roller of the
underlying bearing 46. In other respects, the upper surface of bearing adapter
420 may be
substantially the same as bearing adapter 44. When a vertical load is passed
from the pedestal
seat or pedestal roof (as may be) into the resilient member 342, it may tend
to be compressed
against regions 426 and 428, and less compressed (if compressed at all) over
channel 424, such
that the load may pass into bearing adapter 420 to either side of the top
central position.
Figures 7a - 7d
In Figures 7a - 7d, there is a bearing adapter 430, and a resilient pad
432which may be
taken as being the same as resilient member 342. Bearing adapter 430 may be
taken as being the
same as bearing adapter 420 except insofar as bearing adapter 430 may employ
cusp shaped
reliefs or rebates 434, 436, in place of a full lateral slot, such as channel
424. Rebates 434, 436
may have the same general shape in plan view as the underside reliefs shown in
Figures 4a - 4d.
Rebates 434, 436 may be gently merged into the surrounding structure, as by
having angled or
chamfered walls that are smoothly radiused into top surface portion 438 and
into the adjacent
longitudinally extending grooves or channels, 440. In one embodiment, the size
of rebates 434,
436 may correspond to the size of one roller of the underlying bearing 46, and
may, at their
greatest width, subtend about 15 -20 degrees of arc as measured from the
center of rotation of
bearing 46. Alternately, in one embodiment, the dimension of the largest width
of rebate 434 -
436 measured perpendicular to the axis of bearing 46, may be in the range of
about 1/2 to 1 inch.
When vertical loads are passed from the sideframe pedestal into resilient
member 342 and then
into bearing adapter 430, those loads may tend to be introduced to either side
of the underlying
central roller bearing position. That portion of resilient member 342 lying
over rebates 434, 436
may tend not to be compressed vertically to the same extent (if at all) as the
adjacent regions of
resilient member 342 that may overlie the generally H-shaped upper table-like
surface 445 of the
bed of bearing adapter 430.
Figures 8a - 8d
In the embodiment of Figure 8a, there may be a bearing adapter 450 and a
resilient pad
member 452. Bearing adapter 450 may have an underside 453, and therefore an
underside
CA 02490924 2012-08-13
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interface with bearing 46, that is the same, or substantially the same as the
underside of bearing
adapter 430 or 420, which may include arches for bracketing the outer ring, or
casing, of bearing
46 and a circumferentially extending groove as previously described herein.
Bearing adapter
450 may also have an upper surface, or upper interface for mating with
resilient pad member
452, that is substantially the same as the upper surface of bearing adapter 44
previously
described.
Resilient member 452 may be substantially the same as, or similar to,
resilient member
342, and may differ therefrom to the extent that the underside of resilient
member 452 may have
a laterally extending slot, relief, rebate or channel 454 that extends fully
thereacross. Channel
454 may have inclined or chamfered flanks, and the flanks may be smoothly
radiused into the
back 456 of channel 454 and the adjacent lands 458 and 460 lying to either
side thereof, and
through which vertical loads may tend to be passed into the upwardly facing
bed surface of
bearing adapter 450.
Figures 8e and 8f
In the embodiment of Figures 8e and 8f, bearing adapter 450 may be combined
with a
mating resilient member 462. Resilient member 462 may tend to be substantially
the same as
resilient member 452, but rather than having a channel in the downwardly
facing surface,
resilient member 452 may have a laterally extending channel 464 formed in the
upwardly facing
interface portion thereof, thereby dividing the upper surface into a pair of
spaced apart land
regions 466, 468 lying to either side of channel 464. The width of channel 464
may be similar to
that of channel 454, and may correspond to the width of one roller of the
underlying bearing. As
with channel 454, channel 464 may have chamfered flanks, or sides, or slopes,
and those slopes
may be smoothly radiused into the back of the channel and into the adjoining
interface regions
466, 468 that bear against the underside of the pedestal seat, or pedestal
roof, as may be.
Figures 8g and 8h
In the embodiment of Figures 8g and 8h, bearing adapter 450 may be surmounted
by a
resilient member 470. Pad member 470 may have a central region 472 having
fonned within it
internal features 474 of lesser stiffness than the body of the adjacent
regions 475 and 476 lying to
either side thereof. That is, the material of which resilient member 470 is
made may have a bulk
modulus of elasticity of some value. The bulk modulus of elasticity of the
material of features
474 may be of some lesser value, such that, once a vertical displacement is
imposed upon the
upper surface 476 of resilient member 470, as might be done by a vertically
loaded member
CA 02490924 2012-08-13
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whose stiffness is much greater than resilient member 470, such as a
reinforced pedestal seat or
pedestal roof, the mean force per unit area developed in central region 472
may be less, if not
much less, than the corresponding mean force per unit area of the adjacent
regions. For example,
internal features 474 may be substantially completely gas, such as air or
carbon dioxide. It may
be that features 474 may have the form of blind bores 478 of circular section,
extending some
distance along resilient member 470, being centered on the lateral plane of
symmetry of resilient
member 470. It may be that the length of bores 478 may correspond roughly to
one roller or
underlying bearing 46, or perhaps as much as 1 - 1/2 rollers. In one
embodiment, features 474
are more highly concentrated over the axial position of the underlying bearing
races.
Figures 8i and 8j
In the embodiment of Figures 8i and 8j, bearing adapter 450 is surmounted by a
pair of
first and second resilient members 480, 482 that, taken together, are
substantially the same as
resilient member 342, except insofar as there is a gap 484 between them when
installed. First
and second resilient members 480, 482 may be equal in size, such that the
resultant gap, 484 may
tend to be centered over, and may have roughly the same circumferential extent
as, a roller of
underlying bearing 46. The substantially planar inwardly extending regions 481
and 483 of
resilient members 480 and 482, respectively, may, between them, overlay more
than 2/3 of the
substantially horizontal, upwardly facing surface of bearing adapter 450. They
may overlay
between half and 9/10 of that upwardly facing surface. In one embodiment each
of regions 481
and 483 may overlie more than 1/3 of the upwardly facing surface, and less
than 9/20 of that
surface. In one embodiment they may each overlie between 35 and 45 % of the
surface.
Figures 9a - 9c
In the embodiments of Figures 9a - 9c, a bearing adapter, such as bearing
adapter 450,
may be surmounted by a resilient member having cusp shaped reliefs or rebates
formed therein,
of similar nature, and shape, to those previously described. Those cusps may
be identified as
488, 490, in the underside of resilient member 492 of Figure 9a, or as cusps
494, 496 in the
upper surface of resilient member 498 of Figure 9b, or cusps 500, 502 that
extend fully through
resilient member 504 of Figure 9c. In each case, the cusps may tend to yield a
region above the
top central portion of the underlying bearing races through which reduced
vertical loading is
passed from the pedestal roof to the bearing adapter.
CA 02490924 2012-08-13
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Figures 10a - 10e
In the embodiments of Figures 10a to 10e bearing adapter 450 may be surmounted
by a
resilient member 510, 512 or 514, each having an array of longitudinally
extending slots be it
516, 518 or 520. Array 516 may extend through the full depth of section, array
518 may be
formed in the upper portion, and extend only partially through the section,
and array 520 may be
formed in the lower portion and extend upwardly only partially though the
section. The central
region 522, 524 or 526 of each resilient member may tend to have a lower mean
vertical stiffness
per unit area than the adjacent regions of unslotted material to either side
thereof Consequently,
vertical loads may tend to be passed predominantly to either side of the
central slotted region.
This central slotted region may tend to lie over the top center of the
bearing, and over the top
center of the races of the bearing.
Figure 10f
In Figure 10f, bearing adapter 450 is surmounted by a mating resilient member
530 that
is substantially the same as resilient member 342 except insofar as it has end
regions 532, 534
that are made of a material having a first bulk modulus of elasticity, or a
first response to vertical
loading, and a central region 536 that has a second bulk modulus of
elasticity, or a second
response to vertical loading. For example, regions 532 and 534 may be made of
a higher density
polymeric material than central region 536. Central region 536 may have a
lower vertical
stiffness per unit area than adjacent regions 532 and 534, such that when
squeezed between the
pedestal roof and the bearing adapter, as by a vertical load, the force
transmitted through regions
532 and 534 may tend to be disproportionately greater on a force per unit area
basis than through
region 536. Region 536 may have a width corresponding to the width of roughly
a single roller
of bearing 46.
Figure lOg
In Figure 10g, bearing adapter 450 may be suunounted by a resilient member
540.
Resilient member 540 may have an array of bores, or voids, 542 formed therein
in a central
region 544. Adjacent regions 546 and 548 may lack such bores or voids. The
mean vertical
stiffness per unit area of central region 544 may be less than the
corresponding mean vertical
stiffness per unit area of regions 546, 548, such that vertical loading of
resilient member, as
when loaded by vertical forces imposed by a sideframe pedestal, may tend to be
carried
preferentially, or disproportionately by the adjacent regions 546 or 548.
Voids 542 may extend
fully through the thickness of region 544, or may extend only partially
therethrough.
CA 02490924 2012-08-13
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Figures ha and lib
In Figure lla an alternate wheelset to sideframe pedestal interface assembly
may include
bearing adapter 450 mounted to bearing 46. Resilient member 342 may be mounted
to bearing
adapter 450. Another member 550 may be mounted between resilient member 342
and the
pedestal roof 552. Member 550 may be a pedestal seat 554 having a downwardly
facing pad
engagement interface, indicate generally as 556, and an upwardly facing
surface 558 for mating
with the pedestal roof Pedestal seat 550 may have the general folin of a
Dynaclip pedestal roof
liner, including longitudinally extending members for grasping the sideframe,
in the nature of
sprung, curled up edges that may seat in a spring fit to the sideframe on
either side of the
pedestal roof Pad engagement interface 556 of pedestal seat 554 may include a
pair of spaced
apart, downwardly extending pedestal members or plates, or standoffs,
indicated as load transfer
members 560, 562. Members 560, 562 stand proud of the downwardly facing
intervening
portion 564 of pedestal seat 554 by a height (or depth, as it my alternately
be termed) that may
be as great as, or greater than, the deflection of the underlying resilient
member 342 when truck
22 is loaded to some level, be it the full rated capacity of the truck, or
some value representing
the mean in service loading of the truck plus, for example, one or two
standard deviations from
that mean loading. The spacing between members 560 and 562 may be greater than
the width of
one roller of the rollers in the roller bearing, and may be in the range of
3/4 to 1 ¨ 'A inches, and
may be centered over the top of bearing 46. Members 560 and 562 could also be
formed from a
single rectangular plate, having an H-shaped footprint defined therein,
similar to the H-shaped
footprint described above in the context of bearing adapters and resilient
pads.
Figures 11c to lie
In the alternate embodiment of Figures 11c, a pedestal seat 566 may be used in
place of
pedestal seat 554. Pedestal seat 566 may have sideframe indexing or engagement
features, such
as may be in the nature of lugs 568, 570 formed by notching an upturned side
flange. These lugs
may engage a similar mating lug mounted centrally on the pedestal roof lateral
centerline.
Pedestal seat 566 may include a central body portion 572, which may be in the
nature of a
substantially rectangular plate extending between the upturned lugs, and
extending under the
length of the sideframe pedestal roof for a length that may generally
correspond to the length of
underlying bearing adapter 450. Vertical loads may be passed from the pedestal
roof into
resilient member 342 and bearing adapter 450. The downwardly facing resilient
pad load
transfer interface 574 of pedestal seat 566 may include a laterally extending
slot, rebate, relief, or
channel 576 formed therein, and centered over the axis of rotation of bearing
46. (Alternatively,
CA 02490924 2012-08-13
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an H-shaped land could be defined by foiming cusps in seat 566 in the
substantially planar
horizontal central portion 572, in the manner of the cusps described above.)
The depth of the
relief, or channel 576 (or cusps, as may be) may be as great as, or greater
than the vertical
deflection of resilient member 342 when vertical loads are passed from the
pedestal seat during
operation of truck 22. As noted above, the depth of the relief may be based on
the deflection of
the resilient pad at the full rated load of the truck, at the mean loading, at
the mean loading plus
one, two, or three standard deviations, or another design value. In one
embodiment the depth
may be chosen such that, in most, if not all regimes of operation a gap may be
maintained
between the top of resilient member 342 and the underside of the central
portion of the relief, be
it channel 576. This same criterion may apply to one or more embodiments of
the other
embodiments described herein for establishing a vertical load path
discontinuity.
Whether in the context of an embodiment of Figure 11a, Figure 11c, or some
other, it
may be understood that a similar result may be achieved by forming a pedestal
seat roof having a
downwardly facing interface for mating directly with, for example, resilient
member 243,
wherein that downwardly facing interface is the same, or similar to, that of
either pedestal seat
member 554 or 556, having a pair of spaced apart blocks, in which the pairing
of the blocks, (or
a single plate formed to have an H-shaped footprint as described), and the
spacing may be
centered to run laterally over the axis of the bearing, such plate or profile
being welded in place,
for example.
Figures 12a to 12c
In the embodiment of Figures 12a - 12c, there is a bearing adapter 580 which
may have
an underside that may have a bearing engagement interface similar to that of
bearing adapter
450. The top side of bearing adapter 450 may include a central region 582, and
two adjacent
side regions 584 and 586. Central region 582 may be about an inch wide, and
may have an
upwardly facing surface 588 that is substantially planar, and that may tend to
lie in a horizontal
plane when installed in an at-rest position of a railroad car on level tangent
track. Side regions
584 and 586 may have upwardly facing surfaces that stand proud of surface 588.
Side regions
584 and 586 may be formed on a radius, RI. That radius, RI, may be (nominally,
or actually) a
60 inch crown radius, with the axis of the crown being perpendicular to the
axis of rotation of
bearing 46. Bearing adapter 580 has corner abutments 590, and arches 592, and
end walls 594.
The end walls and the adjacent corner abutments 590 at each end form a channel
shaped opening
such that, when installed, the thrust lugs of the pedestal jaws lie in the
channel shaped opening.
CA 02490924 2012-08-13
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A resilient member 595 seats on top of bearing adapter 580. Resilient member
595 has a
central portion 596 that runs between end portions 597 and 598. End portions
594 and 598 may
include downwardly depending legs 600 and 602 that may seat inside the corner
abutments, and
a depending skirt 604 that may seat against end wall 594. The upper surface
606 of resilient
member 594 may be flat, and may matingly engage the pedestal seat or pedestal
roof as may be.
The lower surface of central portion 596 may seat upon the upwardly facing
surfaces of regions
584 and 586. Inasmuch as those surfaces are proud of the surface of central
region 582, vertical
loads may tend to compress those regions of resilient member 594 that lie over
regions 584 and
586 than that region of resilient member 594 that lies over central portion
586. In one
embodiment the underside 608 of resilient member 594 may be formed on a radius
R2 that may
be the same as, or at least nominally similar to radius RI, such that the part
may matingly
engage, and, when undeflected, may leave a gap between the underside of
resilient member 594
and the upwardly facing surface of central region 582.
In one embodiment, resilient member 594 may include an internal member 610
such as
may be a plate. Internal member 610 may be made of a steel or predominantly
iron based alloy,
and may be bonded or cast inside resilient member 594. Internal member may be
substantially
planar, and may, in one embodiment, extend throughout the majority of the
central portion of
resilient member 594. In another embodiment, there may be two internal members
610, one
being located to seat predominantly, or entirely, over each of regions 584 and
586, and being
spaced apart from each other.
Figures 12d and 12e
Figures 12d and 12e show another embodiment of bearing adapter and resilient
pad
combination. The bearing adapter may once again be bearing adapter 580, as
shown in Figures
12a to 12c, and described above. The resilient member may be a laminated
resilient assembly
612 that may include a bottom skin, or plate 614 formed to seat upon regions
584 and 586 of
bearing adapter 580. Plate 614 may be made of a metal, such as steel. Plate
614 may leave a
gap over central portion 582 of bearing adapter 580. Plate 614 may have a
bottom surface
formed to conform to the upwardly facing curved surfaces of regions 584 and
586. Plate 614
may also have indexing or locating features, such as may be in the nature of
laterally extending
locating lugs, or fingers, or claws, or tabs, with downwardly curved toes or
tangs or tabs 616
such as may bracket a laterally extending lug 618 of bearing adapter 580.
CA 02490924 2012-08-13
- 30 -
A first layer of resilient material, indicated as 620, may be bonded to the
upper surface of
plate 614. An intermediate plate 622 may be bonded atop layer 620. A second
layer 624 of
resilient material may be bonded to intermediate plate 622. A top plate, or
pedestal liner 626
may be mounted above layer 624, and may have tangs 628 for location about lugs
630 mounted
on sideframe 26 on either side of the pedestal roof 632.
Figures 13a and 13b
Figures 13a and 13b show an alternate embodiment in which a bearing 640 has a
casing
642 having a bearing adapter integrally formed thereon. Bearing 640 is, in
most respects, the
same as, or similar to bearing 46 in terms of general construction, race
location, number and size
of rollers, and so on. In addition to having an upper portion 644 that may
have substantially the
same upper surface bed features as bearing adapter 44, and so being able to
mate with resilient
member 342, upper portion 644 may include internal cavities 646, 648 formed to
lie over the
apex of the bearing races in the top dead center position. Cavities 646 and
648 may be centered
over the axis of rotation of the roller bearing races of bearing 640. A web
650 may run
circumferentially between cavities 646 and 648, centrally between, rather than
over, the bearing
races. In the circumferential direction, cavities 646 and 648 may have an
extent corresponding
to, or perhaps somewhat greater than the size of one roller. Similarly, in the
axial direction,
cavities 646 and 648 may have a length as great as or greater than the length
of one roller. The
shape of cavities 646 and 648 is such as to leave a lower arch, or ring
section 652 over the
uppermost roller position, and an arched roof portion 654, which may tend to
distribute vertical
loading to either side of the uppermost roller position. The juncture between
arched roof portion
654 and ring section 652 may be on a smooth radius.
Friction Surfaces
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
CA 02490924 2012-08-13
- 31 -
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, ittõ and a co-efficient of
dynamic or kinetic friction, K.
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 of 0.15
to 0.45, may be in
the narrower range of 0.20 to 0.35, and, in one embodiment, maybe 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, (those
documents being incorporated herein by reference)
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 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, maybe 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
CA 02490924 2012-08-13
- 32 -
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.
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
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.
Further still, the various embodiments described herein may employ a four
cornered damper
CA 02490924 2012-08-13
- 33 -
wedge arrangement, which may include bearing surfaces of a non-stick-slip
nature, in
combination with a self steering apparatus.
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.
