Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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END STRUCTURE ASSEMBLY FOR HOPPER CAR
FIELD OF THE INVENTION
This invention relates to structures for railcars such as may be applicable,
for
example, to the reinforcement of hopper cars, and, in a specific example, to
the structural
transition from a hopper of a hopper car body to the rail car truck end
structure.
BACKGROUND OF THE INVENTION
The design of railway hopper cars is governed by three main requirements.
First, the
fully loaded weight of the car must not exceed 286,000 1b. Thus to maximize
useful, load car
designers try to minimize car weight. At present an empty grain hopper car may
typically
weigh about 70,000 1b., such that lading in excess of 200,000 1b. is
permissible. Second, the
car must withstand a draft load which may be in excess of 500,000 Lbs. Third,
the car must
not buckle under buff loads when slowing or stopping. Under the first, dead
weight, loading
condition the car may be modelled as a simply supported hollow beam carrying a
distributed
vertical load in excess of 200,000 1b., with a corresponding bending moment
distribution.
Under the second, tensile draft, and third, compressive buff, loading
conditions the car is like
a column, taking tensile and compressive loads.
The general structure of contemporary curved-sided hopper cars can be
idealized as a
load bearing monocoque in the form of a hollow, downwardly opening, generally
C-shaped,
thin walled, low aspect ratio column. At each column end, the load is
transferred through a
transition structure from the shell into a stub sill and coupler by which the
railcar is
connected to the next rail car. The challenge in designing the structure for a
hopper car, in
general, is to reduce the mass of the thin shell, and any supporting
structure, to a minimum
while still maintaining the structural integrity required to withstand the
given loads, and to
transfer those loads between the couplers and the body shell. When the shell
is made too thin
it fails in compression due either to global buckling of the structure, or to
the local buckling
phenomenon of wrinkling. In such a hollow shell structure, the ability to
resist the
compressive buff load, without buckling, requires that the principle
longitudinal structural
components of the car, those being the roof and side walls, work together as a
single
integrated structure.
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The hopper car's side structure contributes to its ability to withstand
compressive
buff loads and lateral loads in corners as well as the customary loads
experienced due to
lading. The side structure and the roof structure also interact to stabilize
each other. Side
sheets have been made of several rolled sheets cut to the arc length measured
from the side
sill to the top chord, with their rolling direction perpendicular to the
longitudinal axis of the
car, butt welded together along their side edges. The side sheets require a
significant amount
of assembly time and effort, and the resulting butt-welded seams are oriented
perpendicularly
to cyclic tensile draft loads.
Hopper car designs also face the difficulty of arranging the transition
structure for
carrying loads from the end hoppers to the shear plates and bolsters which
actually rest on
the trucks, that is, in the area where the shear plate, the end hopper slope
sheet, and the
hopper come together. Current industry designs do not tend to increase the
stiffness of the
side construction from the bolster toward the end hopper compartment. It is
advantageous to
provide an increase in the local stiffness of the hopper shear plate, the
hopper sheet
extension, and the side sill, but without increasing the thickness of those
members over their
full lengths. If the side sills are made thicker over their entire lengths, a
large amount of
material would be added that would not be used effectively.
In general, it would be advantageous to have an improved hopper car shell
structure.
It would be advantageous to have, and there has been a long felt need for, an
improved
hopper car side sheet. Finally, there has been a long felt need for an
improved structure to
transfer the load from the hopper car shell structure to the trucks of the
railcar.
SUMMARY OF THE INVENTION
In one aspect of the invention, there is a transition section for carrying
structural loads
between an end hopper of a railway hopper car and a railway hopper car end
structure carried
on a truck, the end hopper having a side sheet, said transition section
comprising a side sheet
extension extending between the side sheet and the end structure, the side
sheet extension
varying smoothly in section between the side sheet and the end structure.
In another aspect of the invention, the hopper car having a side sill of
constant section
extending between, and attached to, the end hopper and the end structure, the
transition
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section is such that the side sheet extension reinforces the side sill between
the end hopper
and the end structure.
In a third aspect of the invention, the end structure having an horizontally
extensive
shear plate, the hopper side sheet having an end slope edge generally oriented
toward the end
structure, the transition section further comprises a shear plate extension
formed integrally
with the shear plate, the extension having a root where if meets the shear
plate and a tip
distant therefrom, the shear plate extension tapering smoothly from the root
to the tip, and the
shear plate extension bent downwardly from the shear plate on a smooth,
continuous curve;
and the side sheet extension has a smoothly curved profile which melds with
the end slope
edge and has a distal portion for lying smoothly against the end structure and
the shear plate
extension lies along and is attached to at lest a portion of the side sheet
extension and acts as
a flange therefor.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention and to show more clearly
how it
1 S may be carned into effect, reference is 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 1 is a general arrangement view of an hopper car incorporating the
present
invention;
Figure 2 is a longitudinal centre-line cross-section of the hopper car of
Figure 1;
Figure 3 is a plan section of the hopper of Figure 1;
Figure 4 is a lateral cross section of the hopper of Figure 1;
Figure 5 is a half sectional plan view of a bolster and shear plate of the car
of Figure
1;
Figure 6 is an end view detail of a side sill and bolster of the hopper car of
Figure 1;
Figure 7 is an enlarged detail of the side sill of Figure 6;
Figure 8 is a side view detail of the bolster of Figure 5;
Figure 9 is a sectional quarter view of a side sill transition of the car of
Figure 1;
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The description of the invention is best understood by commencing with
reference to
Figure 1, in which some proportions have been exaggerated for the purposes of
conceptual
illustration.
Referring to the preferred embodiment of Figures 1, 2, 3 and 4, a hopper car
of all
steel construction is shown generally as 20. It has trucks 22 in the customary
manner, upon
which a railcar body 24 rests. The body has end structures 26 and 28 supported
on trucks 20.
Three hoppers 30, 32 and 34 are defined by a combination of left and right
main side walls
36 and 38, respectively; left and right hand, foremost, middle and rearmost
inwardly
downwardly sloping side sheets, 40, 42, 44, 46, 48, and 50, respectively; end
walls 52 and
54; internal bulkhead partitions 56 and 58; and foremost and rearmost sloped
sheets 60, 62,
64, 66, 68, and 70, tied together and reinforced by left and right hand side
sills 72 and 74 and
top chords beams 76 and 78 all of which are attached to end structures 26 and
28 and covered
by a roof assembly 80.
1 S In general terms, the roof assembly 80 and sidewalls 36 and 38 form a
three sided,
downwardly opening thin shelled structure, similar to a monocoque. This thin
shell is, in
effect, wrapped around endwalls 52 and 54 and bulkhead partitions 56 and 58
and extends
downwardly to the level of side sills 72 and 74. End walls 52 and sloped sheet
60, endwall
54 and slope sheet 70, and bulkhead partitions 56 and 58 act in general terms
as frames, or
formers, forming a skeleton to which the monocoque-like structure is attached
like a skin.
The individual members of the structure are relatively thin and flexible
alone, but when
assembled work together mutually to stiffen each other and the entire
structure. The ability of
such a structure to bear service loads generally depends on the ability of the
unsupported
spans between the formers, to maintain their desired shape. The formers shown
are all
upstanding, but need not be vertically upstanding, and need not be parallel to
give a desired
stiffening effect when the skins are welded in place.
In the embodiment shown the distance between each adjacent pair of formers
defines
the fore-and-aft length of one of hoppers 30, 32, or 34. Generally speaking
the sidewalls
extend along the formers between the discharge assemblies of the hopper car,
described
below, and the superstructure which is typically a roof assembly. The steel
sheet required for
the sidewall has an overall sidewall sheet width from a lap joint located
approximately at
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the level of the top of the side sill, to the top chord roof line measured
along the arc of the
wall, i.e., the developed width.
This structure will now be described in greater detail, commencing with end
structures 26 and 28, and working, generally speaking, inwardly and upwardly.
Inasmuch as
the car is largely symmetrical, the following description made in the context
of forward end
structure 26 also applies to rear end structure 28.
As shown in Figures 5, 6, 7, 8 and 9, end structure 26 has a central
longitudinally
extending stub sill 100 in the form of a fabricated box beam which extends
away from
forward hopper 30 (or rearward hopper 34) of body 24. A standard coupler 102
is attached to
the distal end of stub sill 100 so that car 20 may be linked to other rail
cars. A transverse
beam-like bolster structure 104 extends laterally from stub sill 100 and
includes left and right
hand arms 106 and 108. Each arm has a fabricated stepped beam structure with
an outwardly
tapering lower flange. Each arm also has a corresponding pair of parallel
stepped webs. The
depth of the webs decrease outwardly from the centreline 110 such that stub
sill 100 and
arms 106 and 108 form a cruciform 112 of varying depth of section. A lower,
distal portion
of each of arms 106 and 108 rests upon a side bearing and spring assembly of
each of trucks
22 in the conventional manner. On the underside, at the intersection of
cruciform 112 is a
yoke 118, for location about the pivot of each of trucks 22.
The upper face of cruciform 112, lies in a single plane and is welded to a
shear plate
120. Shear plate 120 has an upturned end flange 122, and an opposed bight-
shaped wheel
well rebate 124. Rebate 124 is bounded on its outer and foremost limit by a
forwardly
extending shear plate extension 126 emanating from a root 125 at the body of
shear plate 120
and tapering to a distal tip 127, bent on a smooth radius downwardly, with an
inwardly
tending profile such that it can be welded to hopper 30 (or 34) in the manner
described
below. Outboard of shear plate extension 126 is a side sill tang 128 separated
from shear
plate extension by a tang relief 130. The most distant tip of tang 128 from
bolster structure
104 is indicated as 129. As shown in Figures 5 and 9, distal tip 127 of shear
plate extension
126 extends away from bolster structure 104 longitudinally beyond the
longitudinal location
of tip 129 of tang 128.
The left and right hand, parallel, spaced apart, longitudinally extending side
sills 72
and 74 rest upon, are welded to, and are supported by, the outboard margins of
shear plate
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120. The farthest extremities of side sills 72 and 74 extend along shear plate
120 to lie
above, and to benefit from the support of, bolster structure arms 106 and 108.
As shown in
the section of Figure 7, each of side sills 72 and 74 has an open, roll
formed, smoothly
radiused section having a first, horizontal wall 136 and an adjoining, outer
vertical wall 138.
The first horizontal wall 136 is for resting upon, and welding to, sheer plate
120. The
adjoining, outer, vertical wall 138 gives onto an upwardly and inwardly angled
upper leg
140. At the other extremity of the section, an angled lower leg 142 extends
upwardly and
inwardly from horizontal wall 136.
As shown in the enlarged detail of Figure 7, which is typical, forward hopper
side
sheet 40 has a main planar, trapezoidally shaped lower portion 146, and a much
smaller,
minor upper portion designated as sill flange lip 148 bent at an angle for
mating with the
tangent angle of the lowermost portion of main side sheet 36. Furthermore, as
is typical,
forward bulkhead partition 58 is provided with a step, or notch, 144, into
which the lower
edge of side sheet 36 may seat. Legs 140 and 142 of side sill 72 extend to
meet the upper and
lower portions of forward hopper left hand side sheet 40, and, when welded
thereto, form a
stiff, closed hollow section.
As shown in Figures 2, 4 and 8, each of end hoppers 30 and 34 has an end slope
sheet
either 60 or 70. The end slope sheet has a trapezoidally shaped lower portion
150 and a main
sidewall contour profile-following upper portion 152. The slope sheet 60 or 70
is supported
from the inner end of stub sill 100 by generally triangular, lightening hole
relieved, left and
right hand gussets 154 and 156 welded at a compound, generally outwardly
leaning angle
therebetween. Both backed by a substantially vertically oriented transverse
shear plate 158
which extends from bolster structure 104 upwardly to meet end slope sheet 60
or 70. A pair
of parallel, spaced apart, channel shaped end slope sheet outer stiffeners 160
have their toes
welded to end sheet 60 or 70. Stiffeners 160 extend upwardly along the slope
of, end sheet
60 or 70, from shear plate 158 to an hollow, closed triangular section,
laterally extending
transom 162 . Transom 162 is located to support end hopper 30 or 34, as the
case may be, at
the intersection of end slope sheet 60 or 70 and vertically upwardly extending
end wall 52 or
54. Finally, a stanchion, or stem post 164 extends vertically upward from the
outer end of
stub sill 100 to meet centrally, and to extend past, transom 162 and continues
upwardly
against end wall 52 or 54 to a level roughly equal to the height of top chords
76 and 78,
described below.
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Foremost hopper 30 is bounded by front end wall 52 and forward hopper slope
sheet
60, described above. The foremost hopper 30 is also defined by an opposed,
main side wall
contour profile mating, forward bulkhead partition 56. The foremost hopper 30
is further
bounded by left and right main side walls 36 and 38 which meet at their lower
extremities
S with left and right downwardly and inwardly sloping, trapezoidally shaped
forward hopper
side sheets 40 and 42; trapezoidally shaped rearward slope sheets; and roof
assembly 80,
described below. The basic inverted rectangular pyramid structure of forward
hopper
discharge assembly 166, giving onto outlet 168, is formed by welding the
mating seams of,
opposed slope sheets 60 and 62 to opposed side sheets 40 and 42. Similarly,
middle hopper
32 is bounded by partitions 56 and 58, main side walls 36 and 38, hopper side
sheets 44 and
46, slope sheets 66, and roof assembly 80. Hopper 32 has a corresponding
discharge
assembly 170 and outlet 172.
The rearmost hopper 34 is bounded by rearward bulkhead partition 58, rear end
wall
54, left and right main side sheets 36 and 38, left and right downwardly and
inwardly sloping
rear hopper side sheets 48 and 50, rear hopper forward and rearward slope
sheets 68, 70, and
roof assembly 80. Hopper 34 has a discharge assembly 174 and outlet 176.
The arrangement of structure at the intersection of shear plate 120 of end
structure 26
(or 28), hopper end slope sheet 60 or 70 of hopper 30 or 34, and hopper side
sheet 40, 42, 46
or 48, as the case may be, is illustrated, typically, in Figures 7, 8 and 9.
Side sill 72 or 74
rests on shear plate 120. The two are welded together along the outer edge of
shear plate
120, the inner edge of side sill 72 or 74, and around the peninsula shaped
profile of tang 128
and tang relief 130. Hopper sloped side sheets 40, 42, 48 and 50 each have an
extension 182
reaching out to lie along, and be welded to, the end portion of side sill 72
or 74. As shown,
side sheets 40, 42, 48 and 50 extend past the locus of intersection with, and
at which they are
welded to, slope sheet 60 or 70 of end hopper 30 or 34. The side sheets 40
have a long,
smooth, large radius transition section 184 which mates with the downward
turned ear of
shear plate extension 126. That is, as shown in Figure 5, shear plate
extension 126 is formed
to lie along, and be attached to, the lower, curved edge 185 of transition
section 184 of side
sheet extension 182. As shown, sheer plate extension 126 acts as a flange
along the lower
edge of side sheet extension 182. When welded together, use of this structure
reduces the
load which must be carried through side sills 72 and 74 from hopper 30 and 34
to shear plate
120, provides additional structure locally only, and, by being smooth, reduces
or avoids the
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stress concentrations that might otherwise exist at the transition from side
sill 72 or 74 to a
more sharply edged shear plate. A consequent benefit is that the thickness of
the section of
side sills 72 and 74 need not be as thick as it might otherwise be, allowing a
savings in
material, and hence weight, along side sills 72 and 74.
As illustrated in the preferred embodiment of Figure 1, main side walls 36 and
38 are
each formed from a rolled sheet 186 of high strength steel with the rolling
direction aligned
longitudinally, for spanning the distance between end walls 52 and 54. Sheet
186 is cut to the
desired developed profile, stepped into notches 144 and then deflected back to
form up
against the side profile of partitions 56 and 58. Sheet 186 is fillet welded
once on the inside
to the top of trapezoidal lower portions 176 of side sheets, and a second time
externally along
the edge of lips 178 of hopper side sheets 40, 44 and 48 or 42, 46 and 50, as
the case may be,
to form a lap joint.
Although a particular preferred embodiment of the invention, and a number of
alternative embodiments have been described herein and illustrated in the
figures, the
principles of the present invention are not limited to those specific
embodiments. The present
invention is defined by the claims which follow.
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