U.S. patent application number 15/814853 was filed with the patent office on 2019-05-16 for cushioning apparatus for a railway car.
This patent application is currently assigned to Strato, Inc.. The applicant listed for this patent is Strato, Inc.. Invention is credited to Michael RING, Jonathan Sunde.
Application Number | 20190144015 15/814853 |
Document ID | / |
Family ID | 66431235 |
Filed Date | 2019-05-16 |
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United States Patent
Application |
20190144015 |
Kind Code |
A1 |
RING; Michael ; et
al. |
May 16, 2019 |
CUSHIONING APPARATUS FOR A RAILWAY CAR
Abstract
An improved selective travel cushioning device for a railway car
is responsive to both draft and buff loads on the coupler, fitting
into a standard cushioning unit pocket with little or no
reconfiguration of the sill required, while limiting wear on
elastic members in the cushioning unit and exhibiting high energy
absorption.
Inventors: |
RING; Michael; (Lake
Village, IN) ; Sunde; Jonathan; (Somerset,
NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Strato, Inc. |
Piscataway |
NJ |
US |
|
|
Assignee: |
Strato, Inc.
Piscataway
NJ
|
Family ID: |
66431235 |
Appl. No.: |
15/814853 |
Filed: |
November 16, 2017 |
Current U.S.
Class: |
213/30 |
Current CPC
Class: |
B61G 9/10 20130101; B61G
9/06 20130101; B61G 9/22 20130101 |
International
Class: |
B61G 9/10 20060101
B61G009/10; B61G 9/22 20060101 B61G009/22 |
Claims
1. An end-of-car cushioning device for a railway car, comprising: a
yoke having aligned apertures at a front end adapted to receive a
pin or key for attaching the yoke to a railway car coupler, and
having a vertical wall at a second end of the yoke opposite the
front end; a coupler-receiving member adapted to receive buff force
from the coupler and adapted to move inside the yoke; a first stack
of elastomeric units positioned between the coupler-receiving
member and the vertical wall of the yoke, each elastomeric unit in
the first stack comprising a metal plate and at least one
elastomeric pad, said first stack being compressed by draft and
buff loads on the coupler; a front buff plate positioned adjacent
to and rearward of the yoke and connected to a rear buff plate by a
rod; a second stack of elastomeric units positioned between the
front buff plate and the rear buff plate.sub.; each elastomeric
unit in the second stack comprising a metal plate and at least one
elastomeric pad, said second stack being compressed in response to
buff loads on the coupler; wherein, the yoke, the front buff plate
and the rear buff plate are positioned within a center sill of the
railway car.
2. The end of car cushioning device according to claim 1, wherein
the yoke is not mechanically attached to the front buff plate or
the rear buff plate.
3. The end-of-car cushioning device according to claim 1, wherein,
each elastomeric unit in the first stack comprises a metal plate
having a vertically oriented face and an elastomeric member in a
middle portion of the vertically oriented face; wherein at least
one of said plates comprises an edge portion extending around the
elastomeric member, said edge portion having a front surface
feature that cooperates with a rear surface in an edge portion of
an adjacent plate; and wherein at full compression of the first
stack, contact between the front surface feature and the rear
surface of an adjacent plat prevents compression of an elastomeric
member between them beyond a predetermined thickness.
4. The end-of-car cushioning device according to claim 3, wherein,
each elastomeric unit in the second stack comprises a plate having
a vertically oriented face and an elastomeric member in a middle
portion of the vertically oriented face; wherein each plate in said
second stack comprises an edge portion extending around the
elastomeric member, said edge portion having a front surface
feature that cooperates with a rear surface feature in an edge
portion of an adjacent plate; wherein at full compression of the
second stack, contact between the front surface feature and the
rear surface feature of adjacent plates prevents compression of an
elastomeric member between them beyond a predetermined
thickness.
5. The end of car cushioning device according to claim 4, wherein
all of the elastomeric units in the first stack have a raised
feature that mates with a recessed feature in an adjacent plate so
that all of the elastomeric units in the first stack are
nested.
6. The end of car cushioning device according to claim 5, wherein
all of the elastomeric units in the first and second stack have a
raised feature that mates with a recessed feature in an adjacent
plate, so that all of the elastomeric units in the first and second
stack are nested.
7. The end of car cushioning unit according to claim 1, wherein the
front buff plate, the rear buff plate and the second stack of
elastomeric units all have about the same approximately rectangular
plan dimension which substantially corresponds to a rectangular
cross-sectional dimension of the railway car sill; wherein one end
of the rod is received in a recess in the front buff plate forming
a flush front surface on the front buff plate; wherein the rod is
received through aligned apertures in each of the elastomeric
units; and wherein the rod, the front buff plate, the rear buff
plate and the second stack of elastomeric units form an assembly
positioned in the sill rearward of the yoke and separated from the
yoke.
8. The end of car cushioning unit according to claim 6, wherein the
sill has AAR Standard EOC-8, EOC-9 or EOC-10 dimensions.
9. The end of car cushioning unit according to claim 6, wherein the
aligned apertures of the yoke are adapted to receive a pin.
10. The end of car cushioning unit according to claim 9, wherein
the yoke is an F-Type.
11. The end of car cushioning unit according to claim 6, wherein
the aligned apertures of the yoke are adapted to receive a draft
key.
12. The end of car cushioning unit according to claim 11, wherein
the yoke is an E-Type.
13. The end of car cushioning unit according to claim 1, wherein
the metal plates each has a face that substantially fills an
interior cross-section of the sill.
Description
BACKGROUND OF THE INVENTION
[0001] The invention is directed to a cushioning apparatus for a
railway car, and more particularly to a selective travel apparatus
that absorbs draft and buff loads applied to a coupler of a railway
car.
[0002] As is generally known, railway cars are connected to an
adjacent car by a coupler. The coupler is joined to a yoke, for
example an "E-type" or "F-type" yoke, by a draft key or pin, and
the assembly is mounted in a railway car center sill.
[0003] To prevent damage to the railway cars and the laded goods
during operation, and especially during assembly of the railway car
train in the yard, various devices have been installed to absorb
loads on the coupler so that impact forces are not transmitted to
the railway car.
[0004] In a conventional frictional draft gear, one or more elastic
elements, such as a coil spring or a set of elastomeric pads, is
enclosed in a housing mounted in the yoke behind the coupler. A
piston-like element frictionally received in the housing absorbs
buff loads transmitted via a coupler follower which moves inside
the yoke in response to buff impact force applied on the coupler,
and the draft gear is compressed in the yoke in response to draft
loads. The basic draft gear apparatus has been used for decades.
However, in many cases unacceptably large forces are transmitted to
the railway car.
[0005] A hydraulic cushioning unit comprises a piston received in a
cylinder filled with fluid. Such devices may dissipate more force
than a conventional draft gear, but they are known to be prone to
leakage.
[0006] U.S. Pat. No. 2,766,894 describes a selective travel draft
gear with separate cushioning elements for buff and draft loads on
the coupler. In this design, both of the cushioning elements are
located forward of the back wall of the yoke.
[0007] U.S. Pat. No. 2,825,472 describes a selective travel draft
gear which comprises separate cushioning elements for buff and
draft loads on the coupler, but both stacks of cushioning elements
are attached to the yoke.
[0008] U.S. Pat. No. 6,446,820 discloses a selective travel draft
gear of more recent vintage where the separate draft and buff
cushioning elements are coupled and adapted to fit into the draft
gear pocket. These apparatuses have not been very well received,
and may be prone to buckling, wherein a stack of elastomeric
elements is pushed out of alignment and fails to operate according
to specifications.
[0009] All of the above-referenced U.S. Patents are incorporated by
reference.
SUMMARY OF THE INVENTION
[0010] In view of the prior art, one object of the invention is to
provide an alternative cushioning device that provides cushioning
over a range of impact speeds.
[0011] Another object of the invention is to provide a cushioning
apparatus for a railway car that provides cushioning for both draft
and buff loads applied to the coupler, limiting force transmitted
to the railway car over a range of impact speeds, such as may be
encountered during train build, where impact speeds may be in the
neighborhood of 4-14 mph or higher, and during start-up and
stopping. Embodiments according to the invention may exhibit low
displacement per unit of force applied over a range of relevant
force levels.
[0012] Yet another object of the invention is to provide improved
alignment and positioning of elastomeric pads in a cushioning
device, to prevent over-compression, permanent deformation, and
buckling during use.
[0013] Yet another object of the invention is to provide a
cushioning apparatus that absorbs both draft and buff loads in a
compact format, more easily installed in a standard pocket such as
for an AAR standard EOC-9 or EOC-10 configuration.
[0014] These and other objects of the invention are met in one
aspect with an end-of-car cushioning device for a railway car,
comprising: a yoke having aligned apertures at a front end adapted
to receive a pin or key for attaching the yoke to a railway car
coupler, and having a vertical wall at a second end of the yoke
opposite the front end; a coupler-receiving member adapted to
receive buff force from the coupler and adapted to move inside the
yoke; a first stack of elastomeric units positioned between the
coupler-receiving member and the vertical wall of the yoke, said
first stack being compressed by draft and buff loads on the
coupler; a front buff plate positioned adjacent to and rearward of
the yoke and connected to a rear buff plate by a center rod; a
second stack of elastomeric units positioned between the front buff
plate and the rear buff plate, said second stack being compressed
in response to buff loads on the coupler; wherein, the yoke, the
front buff plate and the rear buff plate are positioned within a
center sill of the railway car; and wherein, the yoke is not
mechanically attached to the front buff plate or the rear buff
plate.
[0015] In another aspect, the invention resides in the arrangement
of the plurality of elastomeric units, each comprising a plate and
an elastomeric pad positioned in the middle of the plate. A first
set of the plates is arranged in a rear or "buff" stack and the
plates are each sized to fill the sill area to ensure alignment of
the elastomeric pads. A second set of plates is arranged in a front
or "draft" stack, sized to fit inside a yoke. The edges of the
plates extending around the elastomeric pads are configured so that
the plates can nest with each other, and at full compression the
edges of the plates contact one another to prevent overcompression
of the individual elastomeric pads.
BRIEF DESCRIPTION OF THE FIGURES
[0016] The subject matter regarded as the invention is particularly
pointed out and distinctly claimed in the concluding portion of the
specification. The invention, however, both as to organization and
method of operation, together with objects, features, and
advantages thereof, may best be understood by reference to the
following detailed description when read with the accompanying
drawings in which:
[0017] FIG. 1 is top view of a cushioning device assembly according
to the invention assembled in a railway car sill;
[0018] FIG. 2 is an isometric view of a front portion of a
cushioning device according to the invention;
[0019] FIG. 3 is an isometric view of a rear portion of a
cushioning device according to the invention;
[0020] FIG. 4 is an isometric view of an improved selective travel
cushioning device according to the invention attached to an "F"
Type coupler;
[0021] FIG. 5 is a cross sectional view of the improved selective
travel cushioning device assembly of FIG. 1, taken along view lines
5-5 of FIG. 1; and
[0022] FIG. 6 depicts the response of a cushioning unit to static
buff and draft loads.
[0023] The drawings are not to scale, and features not necessary
for an understanding of the invention are not shown.
DETAILED DESCRIPTION OF THE INVENTION
[0024] Directions and orientations herein refer to the normal
orientation of a railway car in use. Thus, unless the context
dearly requires otherwise, the "front" of a coupler is in a
direction away from the body of the car and "rear" is in a
direction toward the center of the car. Likewise, the
"longitudinal" axis or direction is parallel to the rails and in
the direction of movement of the railway car on the track in either
direction. The "transverse" or "lateral" axis or direction is in a
horizontal plane perpendicular to the longitudinal axis and the
rail. The term "inboard" means toward the center of the car, and
may mean inboard in a longitudinal direction, a lateral direction,
or both. Similarly, "outboard" means away from the center of the
car. "Vertical" is the up-and-down direction, and "horizontal" is a
plane parallel to the rails including the transverse and
longitudinal axes.
[0025] "Elastomer" and "elastomeric" refer to polymeric materials
having elastic properties so that they exert a restoring force when
compressed. Examples of such materials include, without limitation,
thermoplastic elastomer (TPE), natural and synthetic rubbers such
as: neoprene, isoprene, butadiene, styrene-butadiene rubber (SBR),
polyurethanes, and derivatives.
[0026] As used herein, the term "about" associated with a numerical
value is understood to encompass a margin of +/-10% of the value.
An object is said to "substantially fill" a space (such as a
railway car sill) when just enough space is provided to allow the
object to move in the space without interference. This may mean a
clearance of up to about 1/4 inch laterally and up to about 3/4
inch vertically.
[0027] In embodiments, a cushioning device according to the
invention is adapted to fit into an Association of American
Railroads ("AAR") standard pocket. The dimensions of a standard
pocket and permitted tolerances may be set by the AAR. from time to
time, and reference herein to AAR standards refers to standards in
the AAR Manual of Standards and Recommended Practices in effect at
the filing date of this application, including performance
standards, such as M-921-B, for hydraulic cushioning units. A
person having ordinary skill in the art has a general knowledge of
AAR standards and the published AAR standards cited herein are
incorporated by reference as background.
[0028] FIG. 1 depicts a cushioning assembly 10 according to one
embodiment of the invention, including a sill 13, coupler 14, and
front and rear units 20, 30 of the cushioning device installed in
the cushion unit pocket. FIG. 1 depicts center sill 13 with bell
shaped opening 15 adapted to accommodate long shank coupler 14 for
a greater range of coupler mobility, although the invention is not
limited to a long shank coupler configuration.
[0029] In embodiments, cushioning device assembly 10 may be
characterized by a pocket length of about 383/4 inches described in
AAR standard S-183 for an "EOC-9" pocket, or a pocket length of
about 483/4 inches described in AAR standard S-184 for an "EOC-10"
pocket. In other embodiments, the cushioning device may be adapted
to fit other pocket dimensions.
[0030] In FIG. 1, and as used herein, the "cushioning unit pocket",
or simply the "pocket", is defined by front lugs 11 and rear draft
lugs 12 mounted on the interior of center sill 13. According to
embodiments of the invention, the cushioning elements are adapted
to be inside the center sill without significantly reconfiguring
the sill geometry.
[0031] In FIG. 1, the cushioning apparatus comprises a first stack
17 of elastomeric units positioned forward of vertical wall 21 of
the yoke, and a second stack 16 of elastomeric units positioned
behind the first stack 17, between a front buff plate and the rear
buff plate (as shown in FIG. 3). The cushioning unit comprises a
front portion 20 and a rear portion 30, which are not fixed to one
another.
[0032] FIG. 2 is a view of a front "draft" portion 20 of a
cushioning apparatus according to an embodiment of the invention.
Yoke 206 includes rear vertical wall 21 and a front portion
including two aligned apertures 23 adapted to receive a pin 42 (not
shown in FIG. 2). A coupler-receiving member 22, conventionally
termed a "coupler follower" is adapted to receive buff force from
the coupler and adapted to move inside the yoke. In the embodiment
shown, coupler follower 22 includes a recess 24 adapted to receive
the shank end of the railway car coupler 14, such that follower 22
moves under buff force from the coupler. The configuration shown in
FIG. 2 is "F-type", in that a pin is used to attach coupler 14
(shown in FIG. 4) to yoke 206, and walls 26 are on the top and
bottom of the yoke. An "E-type" configuration, using a draft key to
attach the coupler to the yoke using draft key, may also be used
without departing from the scope of the invention, and indeed
without changing the dimensions of elastomeric units 25, or of the
stacks 16, 17.
[0033] For ease of understanding the invention, a single
elastomeric unit 25 is shown in FIG. 2 in the space between
vertical wall 21 and coupler follower 22, each elastomeric unit
comprising a metal plate 225, and at least one elastomeric pad 27.
In actual usage, several elastomeric units 25 form stack 17
contained in this space (as shown in FIG. 4 and FIG. 5), which (in
one non-limiting example) may be about 9-10 inches from the
vertical wall to the follower, in a compressed state, comprising
for example, 10-15 plates and a corresponding number of elastomeric
pads, although other pad sizes and configurations may be employed
to tune performance to a particular type of car or lading. In the
embodiment shown, the elastomeric unit 25 includes metal plate 225
and a single elastomeric pad 27. In other embodiments, multiple
elastomeric pads may be positioned on a plate. FIG. 4 depicts an
installed position where coupler pin 42 engages the front side of
aperture 23. When a draft load is applied on coupler 14 through pin
42, the first stack 17 of elastomeric elements is compressed
between vertical wall 21 and coupler follower 22 which abuts stops
11. The first or "draft" stack 17 is compressed when the coupler is
subjected to buff loads and also when the coupler is subjected to
draft loads. To install the elastomeric units 25 in the front
portion of the cushioning unit, the coupler follower 22 may be held
in place with a predetermined pressure on the elastomeric pads 27,
using a set of destructible shear pins fixing the coupler follower
to the yoke. In the rear stack, two c-shaped spacers (not shown)
may be provided on rear unit 30 between rear plate 32 and nut 54 to
provide a pre-load on the rear stack for installation.
[0034] Referring again to FIG. 2, each elastomeric unit 25
comprises elastomeric pad 27 mounted in a recessed area 29 of the
metal plate 225. The rigid plates may be adapted to prevent
over-compression of the elastomeric pads 27. For example, the
plates may be made of cast or fabricated metal such as steel, and a
stop surface may be provided on the periphery of the plate around
the recess. Additionally, protrusions 28 permit a nesting
arrangement of elastomeric units 25 in stack 17, as shown in FIG. 4
and FIG. 5, which also contributes to alignment of the elastomeric
units 25. Metal-to-metal contact on the stop surfaces occurs when
an elastomeric pad 27 between two adjacent plates 225 is compressed
a predetermined amount, such as 20-80%, and in embodiments 20-60%,
of the uncompressed thickness of the pads. In embodiments, the pads
in the front or draft stack compress about 0.5 inches (from their
uncompressed thickness prior to installation) before metal to metal
contact prevents further compression. The plates 225 forming front
stack 17 extend to the walls and/or the straps of the yoke 206. By
way of example and not limitation, an uncompressed thickness of
each pad 27 forming front stack 17 may be about 1.37 inches.
Installed, under a static load of 32 klb, the thickness of the
draft pads is 0.92. Fully compressed, at the point when
metal-on-metal contact of the plates prevents further compression
of the pads, the elastomeric pads 37 in the draft stack may have a
thickness of 0.68 inches. These dimensions are provided for
guidance and should not be deemed to limit the invention. In
practice many configurations are possible without departing from
the scope of the invention.
[0035] The elastomeric pads 27 may be provided with a through hole
in the center, which aligns with a protrusion, which may be cast,
stamped or fabricated on the plate, for example, and provided to
keep the pads in alignment. The diameter of the through hole may be
referred to as the "inner diameter". The lateral edge of each
elastomeric pad 27 may be curved in a toroidal manner, and the
outside diameter of the pad is measured at the middle of the
thickness dimension of the pad.
[0036] FIG. 3 represents the rear "buff" portion 30 of the
cushioning apparatus, positioned adjacent to and rearward of the
yoke and comprising front plate 31 connected to rear plate 32 by a
rod 34 which passes through a plurality of elastomeric units 35.
Although a single center rod 34 is shown, a plurality of rods may
also be used. Each elastomeric unit 35 comprises a plate 226 and at
least one elastomeric pad 37, similar in construction to the
elastomeric unit 25. However, the plate 226 and the elastomeric pad
37 both have a hole to receive rod 34. As in the description of
FIG. 2, only a single elastomeric unit 35 is shown in FIG. 3,
whereas 10-20 plates 226 and a corresponding number of elastomeric
pads could be employed, depending on the design. The elastomeric
unit(s) 35 substantially fill the sill area to help align
elastomeric units 35 and pads 37. Pads 37 may be shaped like pads
27. In the embodiment shown, each elastomeric pad 37 may be
circular when viewed in plan, having an outer diameter. An "inner
diameter" defines a through hole in the middle adapted to receive
the center rod.
[0037] Pads 37 in the buff stack 16 may have the same general shape
as pads 27 in the draft stack 17 but they are scaled larger. The
maximum design force of the larger pads 37 is higher due to larger
surface area, but the surface pressure on each pad is the same. For
example, and not by way of limitation, the uncompressed thickness
of a pad 37 may be about 1.70 inches and the outer diameter may be
about 8.82. Compressed for installation with a force of about 32
klb, the installed thickness of the pads is about 1.24 inches.
Under full compression, with metal-to-metal contact of plates 226
preventing further compression of pads 37, the pad thickness may be
about 0.91 inches and the outside diameter may reach 10.63 inches.
Thus, in embodiments, the pads and plates are designed to allow
compression of 20-80 percent, and in embodiments 40-60 percent,
where the amount that the pad is compressed at full compression is
expressed as a percentage of the uncompressed thickness of the pad,
prior to installation. Bolt head 33 is flush mounted in front plate
31 so that the rear unit 30 may be mounted directly against front
unit 20. In embodiments, rear unit 30 is not attached to the front
unit 20, which facilitates installation. As shown in FIG. 5, rod 34
is secured by nut 54.
[0038] The same elastomeric material may be used for the
elastomeric pads in the draft stack as in the buff stack, such as a
thermoplastic elastomer.
[0039] The elastomeric units of the draft pack are adapted to slide
between straps 26 of yoke 20. In an E-type arrangement, the yoke is
attached to the coupler using a draft key, but the performance
considerations for the pads and plates are similar.
[0040] In embodiments, draft stack 17 is provided in a
pre-shortened installation configuration, which allows draft
portion 20 and the buff portion 30 to slide into the pocket and
allows the coupler to be installed without interference. A
plurality of shear pins, for example four shear pins pass through
the yoke into the coupler follower 22. The pins break on first
impact, and in this fully-installed or post-installation position,
the coupler is pre-stressed, applying buff force against the first
and second stacks.
[0041] FIG. 6 depicts performance modeling of a cushioning unit
according to the invention using response to static buff and draft
loads. The dynamic response of the material would be dependent on
impact speed and could approach twice the static load values.
Nevertheless, the response to static loads provides information to
guide product design to achieve performance objectives. In this
example, 11 pads are used in the buff stack, each having an
uncompressed thickness of 1.7 inches and an uncompressed diameter
of 8.82 inches. The draft stack comprises 14 pads, each having an
uncompressed thickness of 1.37 inches and uncompressed diameter of
6.63 inches. A static compression test is performed to obtain the
response to static load and subsequent recovery or "release".
Separation of compression and release curves represents hysteresis.
The relatively large hysteresis depicted in the response curves is
at least partly an advantage of using the plates to limit
compression of the elastomeric pads within a predetermined range,
resulting in a greater absorption and dissipation of impact energy.
At the same time, very little permanent deformation is expected
during the lifetime of the cushioning unit, on the order of less
than 10%, preferably less than 5%. The stiffening observed under
buff loads greater than about 400 klb occurs after the draft stack
is fully compressed, and the rear "buff" stack assumes the
remainder of the force absorption. Hysteresis may be expressed as
the ratio of energy absorbed by cushioning unit (W.sub.A) to the
energy input during impact (W.sub.E) (modeled as a static load).
Hysteresis for the cushioning unit may be extrapolated from the
deflection of the buff and draft pads versus applied static force
during compression and release from different starting points
(i.e., pre-loaded, uncompressed and fully compressed). In
embodiments a cushioning unit according to the invention will have
a W.sub.A/W.sub.E ratio derived in this manner of 0.3 to 0.65. The
large distance between the compression and release curves in FIG. 6
indicates relatively high hysteresis for a cushioning unit
according to the invention.
[0042] The description of the foregoing preferred embodiments is
not to be considered as limiting the invention, which is defined
according to the appended claims. The person of ordinary skill in
the art, relying on the foregoing disclosure, may practice variants
of the embodiments described without departing from the scope of
the invention claimed. A feature or dependent claim limitation
described in connection with one embodiment or independent claim
may be adapted for use with another embodiment or independent
claim, without departing from the scope of the invention.
* * * * *