Note: Descriptions are shown in the official language in which they were submitted.
CA 02243910 1998-07-23
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WELL CAR STRUCTURE
FIELD OF THE INVENTION
This invention relates to improvements in the structure of well cars, and in
particular
to a resistance to lateral loads through an improved floor design.
BACKGROUND OF THE INVFNTION
Railway well cars may be considered as upwardly opening U-shaped channels of a
chosen length, simply supported on a pair of railcar trucks. Although single
unit well cars are
still common, there has been a trend in recent years toward articulated, multi-
unit railcars
which permit a relatively larger load to be carried on fewer railcar trucks.
Contemporary well cars may carry a number of alternative loads made up of
containers
in International Standards Association (ISO) sizes or domestic sizes, and of
highway trailers.
The ISO containers are 8'-0" wide, 8' -6" high, and come in a 20'-0" length
weighing up to
52,900 lbs., or a 40'-0" length weighing up to 67,200 lbs. Domestic containers
are 8'-6" wide
and 9'-6" high. Their standard lengths are 45', 48' and 53. All domestic
containers have a
maximum weight of 67,200 lbs. Recently 28' long domestic containers have been
introduced
in North America. They are generally used for courier services which have
lower lading
densities. The 28' containers have a maximum weight of 35,000 lbs.
Two common sizes of highway trailers are, first, the 28' pup trailer weighing
up to
40,000 lbs., and second, the 45' to 53' trailer weighing up to 60, 000 for a
two axle trailer
and up to 90,000 lbs. for a three axle trailer. It is advantageous to provide
well cars with
hitches at both ends. This permits either a single 53' three axle trailer to
be loaded in either
direction, or two back-to-back 28' pup trailers to be loaded.
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The wheels of a trailer can rest in the well, with the front, or nose of the
trailer
overhanging the car end structure at one end or the other of well car unit. A
second trailer
may rest in the well facing in the opposite direction. Alternatively, shipping
containers,
typically of 20 ft., 28 ft, or 40 ft lengths may be placed in the well, with
other shipping
containers stacked on top. Further, well cars may carry mixed loads of
containers and
trailers.
Whichever the case may be, a well car is required to withstand three kinds of
loads.
First, it must withstand longitudinal draft and buff loads inherent in pulling
or pushing a train,
particularly those loads that occur during slack run-ins and run-outs on
downgrades and
upgrades. Other variations of the longitudinal load are the 1,600,0001bs.
squeeze load and the
1,250,000 lbs. single ended impact load. Second, the well car must support a
vertical load
due to the trailers or shipping containers it carries. Third, it must be able
to withstand lateral
loading as the well car travels along curves and switch turn-offs. It is
important to carry these
structural loads while at the same time reducing the weight of the railcars
themselves, first to
permit a greater weight of freight to be carried within the overall maximum
car and load
weight limit, and second to reduce the amount of deadweight that must be
pulled when the car
is empty. Third, a lighter car may be less costly to build.
The U-shaped section of the car is generally made up of a pair of spaced apart
left and
right hand side beams, and structure between the side beams to support
whatever load is placed
in the well, and to carry shear between the sills under lateral loading
conditions.
In earlier types of well car the side sills tended to be made in the form of a
single,
large, beam. While simple in concept, they were often wasteful, having an
unnecessary
amount of material in locations where stress may have been low. It is
advantageous to have
a sill in the form of a hollow section, of relatively thin walls, and to
provide local
reinforcement where required. It is also desirable that the hollow section be
as manufactured
at the mill, whether as tube or roll formed section, if possible, rather than
welded. This often
yields a saving in effort, may permit the use of a higher yield stress alloy,
and may also reduce
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the number of defects or stress concentrations in the resulting structure. As
the wall thickness
decreases the prospect of buckling under buff loads and vertical loads
increases, and measures
to deter buckling would be advantageous. It would also be advantageous to
provide protection
for the sills to discourage damage to the sills due to clumsy loading of
trailers or containers.
In the past, one method of dealing with areas of higher flange stresses in the
side
construction was to use a member of greater weight. As the thickness of
structural members
is reduced it would be advantageous to transfer loads from the railcar trucks
to the bolsters,
and thence to the side sills, more snmothly to discourage or reduce stress
concentrations. One
way to do this is to increase the depth of section at the bolster, with a
consequent increase in
height of the end decking.
SUMMARY OF THE INVENTION
The present invention provides, in a first aspect, a transverse force resolver
for a railcar
having a pair of longitudinally extending side sills, comprising a structure
having one
longitudinal force transfer interface for transferring force to one side sill
and another
longitudinal force transfer interface for transferring force to the other side
sill. A transverse
force transfer interface is provided for transmitting a transverse force to
one of the side sills.
The transverse force transfer interface is offset from the one longitudinal
force connection by
a longitudinal moment arm distance. The transverse force transfer interface
has longitudinal
slip.
Additionally, that aspect of the invention may be such that the longitudinal
force
connections are structurally equivalent to a pin jointed connections. Also,
additionally, in that
first aspect of the invention the longitudinal connections can be for location
at substantially the
same longitudinal location of the railcar. In yet another additional feature
of that aspect of the
invention the force resolver can comprise another transverse force connection
for transmitting
a force to the other side sill, and the other transverse force connection is
offset from the
longitudinal force connection by another longitudinal moment arm distance.
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In a different additional feature of that aspect of the invention, the force
resolver can
include a cross beam and a moment structure mounted thereto. The longitudinal
force
connections are located at opposite ends of the beam. The moment structure
extends away from
the beam; and the transverse force connection is mounted to the moment
structure.
In yet another additional feature of that aspect of the invention, the force
resolver
transverse force connection can include an abutment for abutting a reaction
member mounted
to the side sill. In a still further alternative feature of that aspect of the
invention, the force
resolver can include abutments for abutting reaction stops for transmitting
clockwise and
counterclockwise moments to the longitudinal force connections. And, in each
case, the force
lo resolver moment structure can be a floor panel of the railcar.
In another aspect of the invention, there is a transverse force resolver for a
railcar
having a pair of longitudinally extending side sills, comprising a structure
having a
longitudinal force connection for connection to one of the side sills, and a
pair of transverse
force transfer interfaces for transmitting transverse forces to the side
sills. One of the
transverse force transfer interfaces is offset from the longitudinal force
connection by a
longitudinal moment arm distance; and the transverse force transfer interfaces
have
longitudinal slip.
In an additional feature of that aspect of the invention, the transverse force
resolver is
for a railcar having a pair of spaced apart cross beams extending between and
connected to the
side sills, wherein each of the transverse force connections is mountable to
one of the cross
beams.
In another aspect of the invention, there is a rail car having a pair of
longitudinally
extending side sills. A pair of spaced apart cross beams extend between and
are connected to
the side sills. A pair of force resolvers, as described in the previous aspect
of the invention,
each have one of the transverse force connection mounted to one of the beams,
and the other
of the transverse force connections mounted to the other of the beams. One of
the force
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resolvers has its longitudinal force connection connected to one of the side
sills and the other
of the force resolvers has its the longitudinal force connection connected to
the other of the
side sills.
In a still further aspect of the invention there is a transverse force
resolver for
5 installation between a pair of longitudinally extending side sills of a
railcar, comprising a pair
of longitudinal force connections, one connected to one of the side sills and
the other
connected to the other of the side sills. A pair of transverse force transfer
interfaces are
provided for transmitting transverse forces to the side sills. Each of the
transverse force
transfer interfaces is offset from the one of the longitudinal force
connections by a longitudinal
moment arm distance, and each of the transverse force transfer interfaces has
longitudinal
slip.
In an additional feature of these aspects of the invention the transverse
force resolver
can have longitudinal force transmitting interfaces chosen from the set of
connections
Is consisting of (a) a bolted connection; (b) a pin jointed connection; (c) a
welded connection;
(d) a rivetted connection; and (e) a sliding connection with transverse slip.
Similarly, in an
additional feature of these aspects of the invention, the transverse force
connections have
abutments for transmitting forces to either side of the rail car.
In a further additional feature of any of the above aspects of the invention,
the
transverse force resolver can include a cross beam having longitudinal force
connections at
either end thereof and a pair of mounted structures attached to transmit a
moment thereto. One
of the mounted structures extends longitudinally forwardly and the other
extends longitudinally
rearwardly therefrom. Each of the mounted structures has one of the transverse
force
connections mounted thereto. In a yet further additional feature of that
additional feature, the
transverse force resolver includes a pair of the mounted structures that
extend forwardly of the
cross beam and a pair of the mounted structures extend rearwardly of the cross
beam. Each
of the mounted structures have one of the transverse force connections mounted
thereto.
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In a still further aspect of the invention, there is a floor panel assembly
for a railcar
having a pair of longitudinally externiing side sills, comprising a first
cross member extending
between and connected to the side sills, and a moment arm structure mounted to
the cross
member for transmitting a moment thereto. The moment arm extends away from the
cross
member and has a transverse force ttansfer interface for transmitting a
transverse force to one
of the sills. The transverse force transfer interface having longitudinal
slip.
In an additional feature of this aspect of the invention, the floor panel
assembly can
extend substantially perpendicular to the side sills. In another additional
feature of this aspect
of the invention, the floor panel assembly includes a second moment arm
structure. The first
moment arm structure extends longitudinally forwardly from the cross member
and the second
moment arm structure extends rearwardly thereof. The second moment arm
structure has a
transverse force connection, having longitudinal slip, for transmitting a
force to the other side
sill.
In yet a still further aspect of the invention, there is a well car comprising
a pair of
spaced apart, longitudinally extending side sills. A floor cross member
extends between and
is connected to the side sills. A moment arm structure is connected to the
cross member for
transmitting a moment thereto. The moment arm having a transverse force
transfer interface
for transmitting force to one of the side sills, and the transverse force
transfer interface has
longitudinal slip.
In an additional aspect of that invention, the well car can include a floor
cross beam
that extend between, and is connected to, the side sills, spaced from the
cross member. The
transverse force connection is mouited to the cross beam to transmit force to
the one side sill
through the beam.
In another additional feature of that aspect of the invention, the well car
can further
comprise another cross beam extending between and connected to the side sills,
spaced apart
from the one the cross beam. The cross member is located between the cross
beams and
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another moment arm structure connected to the cross member for transmitting a
moment
thereto. The other moment arm structure has a transverse force connection to
the other cross
beam, and the other transverse force connection has longitudinal slip.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention and to show more clearly
how it
may be carried into effect, reference will now be made by way of example to
the
accompanying drawings, which show an apparatus according to the preferred
embodiment of
the present invention and in which:
Figure la is a plan view of an articulated railcar having three articulated
well car units.
Figure lb is a side view of the articulated railcar of Figure la.
Figure lc is an enlarged plan view of one end unit of the railcar of Figure
la.
Figure ld is an enlarged side view of the end unit of Figure lc.
Figure 2a is a schematic plan view of an unloaded end unit as in Figure lc.
Figure 2b is a schematic plan view of a laterally loaded end unit as in Figure
lc.
Figure 2c is a load diagram of a floor panel assembly of the loaded end unit
of Figure
lc.
Figure 3a is a view from beneath a floor panel of the end unit of Figure ic.
Figure 3b is a side view of the floor panel of Figure 3a.
Figure 3c is a view of a free edge of the floor panel of Figure 3a.
Figure 3d is a view of a welded edge of the floor panel of Figure 3a.
Figure 4a shows a plan view of a moment resolver spine of the end unit of
Figure lc.
Figure 4b is a side view of the spine of Figure 4a.
Figure 4c is a cross section of the spine of Figure 4a taken on section '4c-
4c'.
Figure 5a shows a plan view of the central cross beam of the end unit of
Figure ic.
Figure 5b shows a side view of the cross beam of Figure 5a.
Figure 5c shows a cross section of the cross beam of Figure 5a taken on
section 15c-
5c' .
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Figure 6a shows a typical cross section of a pair of floor panels welded to a
spine as
indicated at cross section '6a-6a' of Figure lc.
Figure 6b shows a typical cross section of an interface between a floor panel
and a
cross beam as indicated at cross section '6b-6b' of Figure lc.
Figure 6c shows a view on Arrow 16c' of Figure 6b.
Figure 6d shows a view on Arrow '6d' of Figure 6b.
Figure 7a shows a section of a side beam of the end unit of Figure id taken on
'7a-7a'.
Figure 7b shows an alternate section to that shown in Figure 7a.
Figure 8 shows an end view of the articulation end of the end unit of Figure
ic.
Figure 9a is an enlarged detail, in plan view of an articulated connection of
the railcar
of Figure lc.
Figure 9b is an enlarged detail, in side view, of an articulated connection of
the railcar
of Figure ld.
Figure l0a is an enlarged detail of a pin joint assembly taken on Arrow 'l0a'
in Figure
lb.
Figure lOb is section of Figure l0a taken on 'lOb - l0b'.
Figure lla shows an alternative floor panel for the railcar of Figure lc.
Figure llb shows a further alternative floor panel for the railcar of Figure
lc.
Figure llc shows a still further alternative floor panel for the railcar of
Figure lc.
Figure lld shows yet another further alternative floor panel for the railcar
of Figure
ic.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The description of the invention is facilitated by commencing with reference
to the
Figures, in which some proportions have been exaggerated for the purposes of
conceptual
illustration. Referring to Figures la and lb, an articulated rail car is shown
generally as 20.
It is made up of three articulated well car units, a first end unit 22, an
intermediate unit 24 and
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a second end unit 26 supported on a pair of standard end trucks 28 and 30, and
a pair of
articulated trucks 32 and 34 located between units 22 and 24, and between
units 24 and 26
respectively.
The mechanism for resolving transverse shear force loads will be described
generally
and in a typical manner, with the aid of Figures lc and ld, and the loading
schematics of
Figures 2a, 2b and 2c. A more detailed structural description and variations
will follow after
the general conceptual description. End unit 22 has a connector end structure,
indicated
generally as 36, an articulated end structure indicated generally as 38, and a
well structure,
indicated generally as 40 extending between them. Well structure 40 has a pair
of opposed side
members in the nature of left and right hand longitudinal beam assemblies 42
and 44, held
apart by a floor assembly 50.
When a lateral load, FL is applied, as for example when unit 22 travels
through a
curve, there will be a tendency for beam assemblies 42 and 44 to deflect, as
grossly
exaggerated in the schematic of Figure 2b. For the sake of simplifying this
conceptual
description, load FL is shown as a single point load at the mid point of unit
22. In actual use
lateral loads would be applied to unit 22 at each location at which a load
rests on unit 22, such
as the container supports. However, the same concepts described would continue
to apply.
FL could typically be the lateral force imparted on a container or a trailer
(carried through its
wheels). For the purposes of conceptual explanation it is shown as being
applied at a central
cross beam such as cross beam 52 of floor assembly 50. Other cross beams
include a pair of
medial cross beams are shown as 54 and 56 and a pair of end cross beams 58 and
60. Initially,
in the unloaded condition, all cross members are at 90 degrees to the lower
side sills of beam
assemblies 42 and 44. This defmes right-angled rectangular areas in the floor,
as in Figure 2a.
Conceptually, were the structure to deflect laterally, without the flooring in
place, the
rectangles would deform into the parallelogram shape shown in Figure 2b.
While the general shape of the bays of the floor changes to a parallelogram
configuration, the arms of H-shaped force resolvers 62 and 64, continue to
extend outwardly
CA 02243910 1998-07-23
at right angles from cross member 70. Consequently, the deflection due to FL
will cause H-
shaped force resolvers 62 and 64 of floor assembly 50 to bind against beam
assemblies 42 and
44 in the regions indicated as "A" and "B" respectively. The binding at "A"
provides a
direction reaction for FL on cross member 70. The binding faces are in
compression at "B",
5 and thereby transmit a force into side beam assemblies 42 and 44. The
reaction to this force
is provided by the adjacent horizontal cross beam 54 or 56, which is placed in
tension. Once
again, the shear in beam assemblies 42 and 44 will cause the neighbouring H-
shaped force
resolver 66 to bind against side sill assemblies 42 and 44 in the regions
indicated as "C" and
"D", and so on, until the shear is carried all the way to end structures 36
and 38 for ultimate
10 reaction by the counter plate which sides on the railcar trunk.
It will be noted that force resolver 62 is subject to a force couple, or
moment, M
a(F112) due to the forces transmitted at regions "A" and "B". This moment is
resisted by the
bolted longitudinal force connection of force resolver cross member 70 at
locations "E" and
"F" to side beam assemblies 42 and 44 respectively, whose sum is equal to the
product of the
longitudinal forces transferred from the side sills, each Fs, multiplied by
the moment arm,
each being b/2 for a total of 2(Fs)(b/2) = Fs(b). In this manner the
transverse force applied
at "A" is reacted by a transverse force at "B", plus a tensile longitudinal
force, FT in assembly
42, and a compressive longitudinal force, Fc, in the opposite direction in
assembly 44. Since
force resolver 62 does not rotate in space, the moment couple of the forces
transferred to and
from assemblies 42 and 44 at locations "E" and "F" multiplied by the width
between assemblies
42 and 44, is equal and opposite to the moment couple of the forces applied at
"A" and "B"
multiplied by the longitudinal moment arm distances defined by the
longitudinal separation of
the effective centers of, for example, "A" from "E" and "B" from "E". In the
specific example
shown these latter distances are each equal and are more or less b/2, the
longitudinal half
width of force resolver 62.
Force resolver 62 is not under longitudinal tensile stress. When railcar unit
22 stretches
longitudinally due to draft loading or due to the tension in the side sill due
to vertical loading,
or both, the connection, or transverse, force interfaces, at "A" and "B" have
longitudinal slip,
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so that large tensile forces can not build up due to tensile strain, or
displacements in the side
sill from vertical and draft loads.
The bolted connections at "E" and "F" can be thought of as approximating, or
being
roughly equivalent to, pin jointed connections for the purposes of conceptual
structural
s analysis. This approximation will remain true provided that the width, that
is, the longitudinal
extent of the bolted connection, is small relative to the overall size of the
"H" shaped force
resolver. That is, in general the moment defined by the forces transmitted at
"C" and "D"
multiplied by their moment arms is large, or very large, relative to any
moment due to twisting
at the bolted connections at "E" and "F". Furthermore, even that twisting is
limited when cross
member 70 is connected at both ends to side beam assemblies 42 and 44.
Ideally, the bolted
connections at "E" and "F" should transmit a purely shear force which causes
either tension or
compression in longitudinally extending side sill assemblies 42 and 44.
Further, the
approximation would remain true even if connection were a pin joint or a
welded connection.
A bolted connection has advantageous fatigue performance and is preferred.
Bolting also
makes it possible to remove and replace damaged cross members relatively
easily.
The structure of well car unit 22 will now be described in detail, commencing
with the
structure of floor assembly 50, followed by side beam assemblies 42 and 44,
and end
structures 36 and 38. For the purposes of the present disclosure the floor
assemblies shown
are all the same, whether considering the multiple unit articulated railcar of
Figures la and lb,
or the single unit well car of Figure ic and id.
Referring to floor assembly 50 of unit 22, the spacing between main cross beam
52
and 28' medial cross beams 54 and 56 is unequal to the spacing between 28'
medial cross
beams 54 and 56 and 40' end cross beams 58 and 60. Four ISO 40' container
cones located
on 40' cross beams 58 and 60 are indicated as 72. The unequal pitch of the
cross members is
such that the well structure 40 can accommodate either two ISO 20' containers,
each with one
end located on cones 72, a single 40' ISO container, also located on cones 72,
a single 45'
domestic container or a single 48' domestic container. Depending on the
configuration of
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container carried in well structure 40, unit 22 is designed also to support an
upper, stacked 40'
ISO container, or single stacked 45', 48' or 53' domestic containers.
Force resolver cross members 70, 74, 76, and 78 are located midway between
each
successive pair of cross beams. They have either short floor panels, left
handed ones
designated as 80 and right handed ones as 82, or long floor panels, left and
right handed ones
designated as 84 and 86, respectively, welded to them as described in greater
detail below.
Four floor panels are generously welded to each cross member to form the H-
shape shown.
At each end of floor assembly 50 there is a pair of load spreading struts 88
and 90. They
transfer longitudinal loads between end structures 36 and 38 and side beam
assemblies 42 and
44 through end cross beams 58 and 60. Left and right hand cross beam socket
fittings 92 and
94 receive the ends of struts 88 and 90, as also described in greater detail
below. Finally, at
either end of floor assembly 50 left and right hand floor panel extensions 96
and 98 are located
between socket fittings 92 and 94 and side beam assemblies 42 and 44. Floor
panel extensions
96 and 98 permit a 53' trailer to be carried in well structure 40.
As noted above, force resolver 62 is made of cross member 70 and floor board
panels
80 and 82. Referring now to Figures 3a, 3b, 3c, and 3d, whether long or short,
the
construction of floor panel 82 is typical of all floor panels. For carrying a
load it has a top
plate 102, having a welded edge 104, for welding to cross member 70, and a
free edge 106
for locating freely slidably against cross beam 54 or 56 (as the case may be).
A pair of spaced
apart, parallel, longitudinally extending channels 108 and 110 are welded,
toes up, to the
underside of top plate 102 . Channels 108 and 110 extend between and terminate
at a welded
edge cross member end support plate 112 which depends from top plate 102 near
welded edge
104, and a free edge cross member support plate 114 which depends from top
plate 102 near
free edge 106. A floor panel side support 116 lies generally in a shallow arc
along, and is
spaced inboard from, the longitudinal side sill edge 118 of top plate 102. An
abutment, in the
nature of a generously welded floor panel corner tab 120, is welded to the
underside near a
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cross beam cut-out 122, and top plate 102 has an upturned lip 124 for facing
beam assembly
42 (or 44, as may be). A ahrust block 126 is welded to the inboard corner,
longitudinal end
face of top plate 102 to bear against cross beam 54 or 56, as is described
below.
Cross member 70 has a downwardly opening channel 130 whose toes terminate at a
S closure plate 132 that is welded to channel 130 to form a closed box
section. Closure plate
132 extends beyond channel 130 to leave horizontal flainges 134 for
accommodaftg, and.
carrying, the downward face of welded edge support plate 112. Cross member 70
terminates at
each end with end flanges 136 having a vertical face 138 for fastening with
bolts to side beam
assembly 42 (or 44), and a pair of horizontal ears, 140 for bolted connection
to the=toe of an
angle iron of that side sill.
Cross beam 52, being typical, is made of a downwardly opening channel 146. A
closure plate 148 is welded across the toes of channel 146 to form a box
section, as above,
with fore and aft extending horizontal flanges 150 for supporting the downward
face of free edge support
plate 114. It also has cast end flanges, 152, for bolted connection to side
beam assemblies 42
and 44 at six places per flange - four on a vertical face 154 and two on
opposed ears 156 for
engagement with the toe of an angle iron of side beam assemblies 42 and 44 as
the case may
be.
On assembly, floor panels 82, 84, 86, and 88, as the case may be, are not
welded to
flanges 152, but are allowed to be located freely thereon. Floor panels 82,
84, 86, and 88 are
located with comer tab 120 snug against beam assembly 40 (or 42) which acts as
a stop. Once
in place, side reaction blocks 160 are generously welded to the vertical side
faces of channel
146 as shown in Figure 6c . In this position one end face of each block 160
acts as a stop bard
against thmst block 126. Thus the distal ends of floor panels 82, 84, 86,and
88, while not
attached to channel 146, are prevented from moving lateraIIy by the inboard
face of beam
2s assembly 40 or 42 in otle direction, and by thrust block 126 in the other
direc6on and so a slip
joint, or slip connection is formed that not only has slip in the longitudinal
direction but also
has a transverse force transfer interface for transmitting transverse force to
either side beam
CA 02243910 1998-07-23
14
assembly 42 or 44 either directly or through the force transfer medium cross
beam 54, 56 or
some other cross beam as the case may be. Floor panels 82, 84, 86, and 88 are
also restrained
longitudinally by shims 162, of the largest possible dimension, fit on
assembly between the
vertical side face of channel 146 and support plate 112. Top plate 102 has cut-
outs to permit
installation of shims 162. The box section formed by closure plate 148
provides cross member
52 with resistance to deflection under longitudinal compressive loads such as
may be imposed
by floor panels 82, 84, 86, and 88.
Referring again to the conceptual illustrations of Figures 2a and 2b, the
initially
rectangular bays mentioned above are defined by longitudinally extending side
beam
assemblies 42 and 44, and by transversely extending cross beam pairs, such as,
for example,
beams 54 and 58. Taking the lateral force once again as FL, and assuming that
half or this
force is carried to each of trucks 28 and 32, as, for example, upon the shear
flow path
indicated as 'S', then the force transferred at each of stops 160 and corner
tabs 120 is
nominally one quarter of F,, . In actual use the precise values of the forces
transferred will
depend on the placement of the loads and the relative stiffness of the various
load paths.
Lateral loading from either side of the car will produce a tensile load in
cross beams 54 and
58. The load is carried across the bolted interface at the end of each beam,
to the respective
side sill, and then to the adjacent floor panel, or panels in the case of
assemblies having stops
160.
A section of side beam assembly 42, identical to side sill assembly 44, taken
in the
region of maximum vertical bending moment at section 17a-7a' is shown in
Figure 7a. It has
a top chord member 166 in the form of a generally square or rectangular hollow
tube 168,
typically with a 1/4" or 5/16" wall thickness, surmounted by a 1" thick top
chord plate 170,
with fillet welds all along the edges. At each section 'X-X', shown in Figure
id, plate 178
is supplanted by a thinner, 1/2" thick plate 180. Returning to Figure 7, a web
174 is mounted
to and extends downwardly from the inner face of hollow tube 168 to meet lower
side sill 176
in the form of a 1/2" thick roll fornvd angle 178 having a 7 3/8" vertical leg
and a 7" inwardly
extending toe. A 1/2" thick reinforcement 182 is welded to the lower face of
the toe of angle
CA 02243910 1998-07-23
178. Stiffeners in the nature of side posts 162 in the form of steel channel
sections, are
welded, toes inward, intermittently along the outside face of side sill
assembly 42 at locations
corresponding to the junctions of cross beams, such as cross beam 52, and
spines such as cross
member 70.
5 In an alternate embodiment, shown in Figure 7b, a top chord member 184 has
an
upwardly opening roll formed, U-shaped channel 186 in place of tube 168. The
toes of channel
186 are welded to the underside of plate 170 (or 180 as the case may be), to
yield a closed
hollow section.
Referring to Figures 8, 9a and 9b, at each end of railcar unit 22 loads
carried in the
10 floor and in the side beam assemblies 42 and 44 are transferred to and from
a connector 190.
There are three primary load paths. The first load path, generally for
carrying vertical shear
loads, is from the connector into the webs of a stub sill 192, thence into a
bolster 194, or
superior cross member 208 to the vertical webs of beam assembly 42 or beam
assembly 44.
The second load path, generally for carrying lateral loads, is from connector
190 through stub
15 sill 192, through shear plate 196 to bulkhead 197 into a spreader plate 200
and thence through
left and right hand struts 88 and 90 into floor assembly 50. The third load
path, generally for
carrying longitudinal loads, is from connector 190 through stub sill 192,
through shear plate
196 to beam assembly 42 or beam assembly 44. A significant portion of the
longitudinal
loads, perhaps 20 or 30 %, is carried from stub sill 192 along a downwardly
curving and
spreading stub sill neck 198 into a spreader plate 200 and thence through left
and right hand
struts 88 and 90 into cross member 58 or 60, as the case may be, and into side
beam assembly
42 or beam assembly 44. The eccentricity of the buff and draft loads, due to
the difference in
height of the centroid of the first motnent of area of the stub sill from the
height of the centroid
of the fnst moment of area of the side beams, is reacted by a couple carried
in bulkhead 197
and bolster 194.
Care has been taken on each of these paths to reduce stress concentrations
that had
formerly been found disadvantageous. On the first path lower side sill 176 and
web 174 end
CA 02243910 1998-07-23
16
at a smoothly curved transition flange 202 which meets main body bolster 194.
Similarly,
welded to the top of each of side beam assemblies 40 and 42 is a tapered
superior transition
member 204 which extends from well beyond the transition of web 174 into beam
assembly
40 or 42, to the end of beam assembly 40 or 42. This permits a deeper
transition section over
the wheel well allowance, and a correspondingly better stress distribution.
Further, it permits
a deeper main bolster 194, and a deeper transition from side beam assemblies
40 and 42 to
bolster 194, with lower stress levels generally, permitting a heavier loading
generally. At the
other end a similar superior transition member 206 carries loads into a cross
member 208 at
the same level as male or female side bearing arms 210 or 212 and allows those
side bearing
arms to be at a greater elevation from the rails, permitting a heavier duty
articulated truck with
greater load bearing capacity.
Along the second load path each of load spreading struts 88 and 90 is pin
jointed to
prevent them from transmitting a bending moment. The pin joints themselves are
of non-
conventional construction to carry high loading. As shown in Figures l0a and
lOb, each strut
has a trunnion 218 built up at each end for capture in apertures 220 of lower
and upper
sandwich plates 222 and 224. Struts 88 and 90 by themselves have insufficient
section to
afford a hole for a pin, given the large forces involved. Similarly, a
circumferential weld
around a stub would lack sufficient weld area. Consequently trunnions 218 are
formed from
a three part assembly. There are two, opposed, hollow, cylindrical, half-moon
shaped outer
shells 226 that lie upon the upper, or lower, surface of struts 88 or 90. They
are welded inside
and out, with externally smoothly ground fillets. Nested inside outer shells
226 is a single
inner disc 228 of significantly smaller outer diameter than the inner diameter
of shells 226.
The gap, or cavity, "G" between shells 226 and disc 228 is filled with
repeated passes of weld
metal. The area for transfer of shear from the longitudinal top and bottom
members 230 and
232 of struts 88 and 90 to their respective trunnions 218 is greatly increased
as compared to
a single circumferential fillet weld. Further, members 230 and 232 need not be
pierced, thus
retaining their entire section. Further still, since members 230 and 232 do
not have to have
enlarged ends, the distance from the centerline of the pin joint to adjacent
structure, is less
than it might otherwise be.
CA 02243910 1998-07-23
17
As noted above, the well car units each have well structures, like end unit
well
structure 40, that are suitable for carrying shipping containers or highway
trailers, or a
combination load. Each end of the unit is equipped with a trailer hitch 236 or
238 for receiving
the king pin of a highway trailer. The decking adjacent to hitches 236 and 238
is kept clear
of obstructions that could interfere with the landing gear, or under-carriage
of highway
trailers. To accommodate this need, and the need that the distance between
brake cylinders
not exceed 175 ft., a pair of saddle-bag brake reservoirs 240 and 242 have
been partially
tucked into the hollow next to the outer face of web 174 beneath top chord
roll formed channel
168 and a brake valve 244 has been mounted between units 22 and 24. Reservoir
240 is the
norlnal, or auxiliary brake reservoir for trucks 28 and 32. Reservoir 242 is
the corresponding
emergency brake reservoir. A standard brake valve 246 and standard combined
reservoir 248
are mounted to the connector end of unit 26, and is used for operating the
brakes of trucks 30
and 34. The brake piping is arranged to suit this location, but is otherwise
conventional in
nature.
All of the elenients of the load paths have now been described in detail. A
number of
other configurations of floor panel are also possible as illustrated in
Figures lla, llb, llc and
lld. To begin, additional pairs of thrust and reaction blocks could be used
rather than one
pair per floor panel. Use of a large number of such blocks would yield a
dovetailed joint
appearance. Other configurations of force resolving floor panel are also
possible. For
example, it appears that a roughly triangular floor panel 250 could be used,
either in a first
alternative as shown in Figure 11a, with two sides in slip connections 252 and
254 on opposite
cross beams and one side 256 bolted to one side sill, or as in a second
alternative, 260 shown
in Figure llb, with opposite sides 262 and 264 bolted to the side sills and
one side 266 in a
thrust and reaction block joint against one cross beam 268. The common feature
of these
alternatives is not that they be triangular, but rather that they employ three
force transfer
interface points, and that those points form a triangle.
In the alternative of Figures 11a the shear will be resolved out of phase.
However, two
such triangular panels can be placed back-to-back, as in Figure llc, such that
each triangular
CA 02243910 1998-07-23
18
bolted shear connection transmits a longitudinal force to one side sill.
Similarly, a pair of
three point force transfer panels can be oriented to lie across the car as in
Figure lld.
However, it is preferred to use a four or six point embodiment in which the
floor panels are
rectangular for carrying highway trailer wheels, and which permit a transverse
couple imposed
on the floor panels to be reacted by a longitudinal couple in the side sills.
In each case, the force transfer at the thrust and reaction blocks is a purely
normal
force, applied across a transverse force transfer interface that is in
compression. No moment
is transmitted across the interface, and no tensile stress is generated to
cause a crack to open.
The bolted connections to the side sills have good fatigue characteristics:
high tensile strength
bolts place the flanges in compression. Furthermore, while it is possible to
construct floor
panels whose longitudinal force transmitting attachments to the respective
side sills are not
located at the same longitudinal location of the rail car, it is advantageous
and preferred, for
them to be at the same longitudinal location.
Although the embodiment illustrated in Figure lc and described above is
preferred, the
principles of the present invention are not limited to this specific example
which is given by
way of illustration. It is possible to make other embodiments that employ the
principles of the
invention and that fall within its spirit and scope as defmed by the following
claims and their
equivalents .
