U.S. patent number [Application Number ] was granted by the patent office on 0000-00-00 for united states patent: re31784 ( 1.
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United States Patent |
RE31,784 |
|
**Please see images for:
( Certificate of Correction ) ** |
Issue Date: |
January 1,
1985 |
Current U.S.
Class: |
105/197.2 |
Current CPC
Class: |
F42B
22/10 (20130101); B61F 5/122 (20130101) |
Current International
Class: |
B61F
5/12 (20060101); B61F 5/02 (20060101); F42B
22/10 (20060101); F42B 22/00 (20060101); B60F
003/00 () |
Field of
Search: |
;105/197A,197D,197DB,224.1,224R,197AD ;267/9R,9A,9B,63R,140,141
;280/716 |
References Cited
[Referenced By]
U.S. Patent Documents
Assistant Examiner: 13
Attorney, Agent or Firm: Breisch; E. Wallace Brams; J.
Stewart
Claims
I claim:
1. A railway truck bolster friction assembly adapted to be
.[.captively.]. retained within a pocket of an elongated truck
bolster member which extends between spaced elongated side frame
members of a railway truck vehicle comprising: elastomeric
.[.friction.]. means adapted to have a first portion thereof in
.[.communication.]. .Iadd.engagement .Iaddend.with adjacent
surfaces of such a pocket and a second portion thereof in
frictional engagement with .Iadd.an .Iaddend.adjacent
.[.portions.]. .Iadd.portion having a surface .Iaddend.of .Iadd.a
.Iaddend.wearing surface means of a column guide of a respective
one of such side frame members.[.,.]..Iadd.; .Iaddend.said second
portion being spaced .[.transversly.]. .Iadd.transversely
.Iaddend.outwardly, with respect to the longitudinal axis of such a
bolster member, from such a pocket and said first portion extending
.[.transversly.]. .Iadd.transversely .Iaddend.inwardly from said
second portion; and said elastomeric .[.friction.]. means being
.[.operative to deform and.]. .Iadd.deformable in shear to
.Iaddend.maintain said frictional engagement, without slipping
.[.between adjacent engaging surfaces.]., during .[.at least.].
initial vertical and transverse movements of such a bolster member
with respect to such a respective one of such side frame members
.Iadd.until such deformation in shear reaches a given
magnitude.Iaddend..
2. A railway truck bolster friction assembly as specified in claim
1 additionally including biasing means to bias said elastomeric
.[.friction.]. means into said .[.communication.]. .Iadd.engagement
with such adjacent surfaces of such a pocket .Iaddend.and said
frictional engagement.
3. A railway truck bolster friction assembly as specified in claim
2 wherein during .[.a.]. subsequent .[.vertical movement.].
.Iadd.relative movements .Iaddend.of such a bolster member
.Iadd.with respect to such a respective one of such side frame
members .Iaddend.said elastomeric .[.friction .]. means are
operative such that at least sections of .Iadd.said surface of
.Iaddend.said second portion will slip with respect to .Iadd.such
.Iaddend.adjacent .[.portions.]. .Iadd.portion .Iaddend.of such
wearing surface means.
4. A railway truck bolster friction assembly as specified in claim
.[.1.]. .Iadd.2 .Iaddend.additionally including said wearing
surface means .[.of such respective one of such side frame members,
and said adjacent portions of said wearing surface means extend.].
.Iadd.extending .Iaddend.downwardly and .[.slope transversly.].
.Iadd.sloping transversely .Iaddend.inwardly, with respect to the
longitudinal axis of such bolster member, to be operative as said
biasing means by providing a wedging action on said elastomeric
bearing means as such a bolster member moves vertically
.Iadd.downward.Iaddend..
5. A railway truck bolster friction assembly as specified in claim
.[.2 additionally including said wearing surface means of such
respective one of such side frame members, and said wearing surface
means includes.]. .Iadd.1 wherein .Iaddend.heat dissipation means
.[.thereon which are operative.]. .Iadd.are cooperable with said
wearing surface means .Iaddend.to .[.directly.]. draw heat from
said adjacent .[.portions.]. .Iadd.portion .Iaddend.of said wearing
surface means and dissipate such heat to the atmosphere.
6. A railway truck bolster friction assembly as specified in claim
2 wherein said biasing means continuously biases said elastomeric
.[.friction.]. means into said .[.communication.]. .Iadd.engagement
with such adjacent surfaces of such a pocket .Iaddend.and said
frictional engagement.
7. A railway truck bolster assembly as specified in claim 6 wherein
.Iadd.support means engage the downwardly facing portion of said
elastomeric means and .Iaddend.said biasing means includes at least
one elongated spring element extending substantially vertically
intermediate said .[.elastomeric friction.]. .Iadd.support
.Iaddend.means and a generally horizontally extending spring
seating portion of such a respective one of such side frame
members, such seating portion being spaced downwardly from said
.[.elastomeric friction.]. .Iadd.support .Iaddend.means.
8. A railway truck bolster friction assembly as specified in claim
7 .[.additionally including.]. .Iadd.wherein said support means is
.Iaddend.a spring follower interposed vertically intermediate said
elastomeric .[.friction.]. means and said spring element, said
spring follower having.[.;.]. an underside surface thereof in
.[.communication.]. .Iadd.engagement .Iaddend.with an upper axial
end portion of said spring element, an upperside surface thereof in
engagement with an underside surface of said elastomeric
.[.friction.]. means and having the .[.transversly.].
.Iadd.transversely .Iaddend.innermost surface thereof, with respect
to the longitudinal axis of such a bolster member, in
.[.communication.]. .Iadd.engagement .Iaddend.with .Iadd.an
.Iaddend.adjacent .[.surfaces.]. .Iadd.surface .Iaddend.of such a
pocket.
9. A railway truck bolster friction assembly as specified in claim
8 wherein said upperside and underside surfaces lay in a common
plane, which plane slopes .[.upwardly as it extends transversly
inwardly, with respect to the longitudinal axis of such a bolster
member, from said second portion.]. .Iadd.upwardly and towards said
second portion from said underside surface of said elastomeric
means.Iaddend..
10. A railway truck bolster assembly as specified in claim 7
wherein .[.the underside surface of said elastomeric friction
member slopes upwardly as it extends transversely inwardly, with
respect to the longitudinal axis of such a bolster, from said
second portion and is in communication with said biasing means,.].
said biasing means exerts a generally upwardly directed force on
said elastomeric .[.friction.]. member and said frictional
engagement primarily results from a horizontal component of said
upwardly directed force .[.as applied at said underside
surface.]..
11. In a railway truck assembly having an elongated bolster member
which is supported adjacent the axial ends thereof on spring groups
seated on spaced elongated said frame members and having bolster
member friction assemblies positioned intermediate the bolster
member and respective column guides of the side frame members, the
improvement comprising: said friction assemblies each having
elastomeric .[.friction.]. means received within a respective
pocket of said bolster member, said elastomeric .[.friction.].
means having a first portion thereof in .[.communication.].
.Iadd.engagement .Iaddend.with adjacent surfaces of said pocket and
a second portion .Iadd.having a surface .Iaddend.thereof in
frictional engagement with a wearing surface means of said column
guide, said second portion being spaced transversely outwardly,
with respect to the longitudinal axis of said bolster member, from
said pocket and said first portion extending .[.transversly.].
.Iadd.transversely .Iaddend.inwardly from said second portion; and
said elastomeric .[.friction.]. means being .[.operative to deform
and.]. .Iadd.deformable in shear to .Iaddend.maintain said
frictional engagement, without slipping .[.between adjacent
engaging surfaces,.]. during .[.at least.]. initial vertical and
transverse movements of said bolster member with respect to said
side frame members .Iadd.until such deformation in shear reaches a
given magnitude.Iaddend..
12. A railway truck assembly as specified in claim 11 wherein
during subsequent vertical movement of said bolster member said
elastomeric .[.friction.]. means are operatie such that at least
sections of said second portion will slip with respect to
.[.adjacent portions of.]. said wearing surface means .Iadd.until
said deformation in shear reaches a given magnitude greater than
said first mentioned given magnitude.Iaddend.. .Iadd.
13. A railway truck bolster friction assembly adapted to be
retained within a pocket of an elongated truck bolster member which
extends between spaced elongated side frame members of a railway
truck vehicle comprising: elastomeric means having a first portion
with surfaces thereof adapted to frictionally engage adjacent
surfaces of such a pocket and a second portion with a surface
thereof adapted to frictionally engage an adjacent column guide
surface of a respective one of such side frame members; said second
portion being spaced transversely from said first portion such that
when said surfaces of said first portion engage such adjacent
surfaces of a pocket said second portion extends outwardly from the
pocket; and said elastomeric means being deformable in shear to
simultaneously frictionally engage such surfaces of a pocket at
such a column guide surface engagements without slipping during
initial relative movements of such a bolster member with respect to
such a respective one of such side frame members until such
deformation in shear reaches a given magnitude. .Iaddend. .Iadd.14.
A device for maintaining engagement between a bolster and the side
frames of a railway truck assembly in which an elongated bolster
extends horizontally between spaced side frames with open ended
pockets in the ends of the bolster being located in spaced adjacent
relationship with surface means on the side frames, respectively,
comprising:
a formed block of elastomeric material of a configuration to be
received in such a bolster pocket with an outer surface of said
block being in deformed engagement with an adjacent one of such a
surface means when the bolster and the side frames are in a
relative position which is the same as the relative position when
said bolster and said side frames are at rest;
said elastomeric block being of a composition that, upon movement
of the bolster relative to such adjacent one of such surface means
to produce a shearing deformation in said block while said block
remains in deformed engagement with such adjacent one of such
surface means, said block initially remains in essentially the same
relative position with respect to such adjacent one of such surface
means until such shearing deformation reaches a first magnitude and
thereafter said block partially moves with respect to such adjacent
one of such surface means until such shearing deformation reaches a
second magnitude greater than said first magnitude and thereafter
said block moves in its entirety with respect to such adjacent one
of such surface means when the magnitude of such shearing
deformation exceeds said second magnitude. .Iaddend. .Iadd.15. A
railway truck assembly comprising: an elongated horizontally
extending bolster; upstanding side frames at the ends of said
bolster, respectively; open sided pockets in the ends of said
bolster, respectively; said side frames having surface means
adjacent the open sides of said pockets, respectively; elastomeric
means in said pockets having outer surfaces in frictional
engagement with said surface means, respectively; and said
elastomeric means being of a composition that, upon movement of
said bolster with respect to said surface means to produce a shear
deformation in at least one of said elastomeric means, one said
elastomeric means initially maintains such frictional engagement by
undergoing shear deformation while remaining in essentially the
same relative position with respect to the one of said surface
means adjacent thereto until such deformation reaches a first
magnitude and thereafter undergoing further shear deformation with
only a portion thereof moving with respect to said one of said
surface means until such deformation reaches a second magnitude
greater than said first magnitude and undergoing still further
shear deformation while moving in its entirety with respect to said
one of said surface means when the magnitude of such shear
deformation exceeds
said second magnitude. .Iaddend. .Iadd.16. A railway truck assembly
as specified in claim 15 wherein said frictional engagement results
from initially deforming said elastomeric means prior to subjecting
said elastomeric means to shear deformation. .Iaddend. .Iadd.17. A
railway truck assembly as specified in claim 15 wherein biasing
means carried by said side frames engages said elastomeric means,
respectively, to bias said elastomeric means into said frictional
engagement. .Iaddend.
Description
Modern three piece railway freight car trucks use rigid wedge
shaped friction members intermediate an axial end portion of the
bolster member and an adjacent side frame. These friction members
provide the fit-up between the bolster and the side frame columns
and serve to snub or damp the freight car suspension.
In the normal travel of railways cars over a railbed, various
differences in the surface profile of the laterally spaced tracks
resulting from rail joints and superelevation of the outside track
on curves, gives rise to a tendency of resonant swaying and
bouncing of the car body. In modern cars with heavy load capacity
and a relatively high center of gravity, the forces and weight
shift of the car resulting from track surface variations becomes so
large at times that a variety of effects may develop such as:
(1) Complete unloading of the wheels on one side of the truck to
the extent of lifting the unloaded wheels off the rail with a high
potential of derailments;
(2) The imposition of extreme stresses on the car body and truck
members; and
(3) Cumulative damage and misalignment of track, ties and roadbeds
through pounding action.
The need for adequate damping of railway vehicle suspensions has
been recognized and to a certain extent alleviated by independent
means. Specifically, as mentioned hereinabove, rigid friction
members, for example as illustrated in U.S. Pat. No. 3,461,815 are
generally utilized to dampen or snub the rocking motion by
frictional resistance developed between the rigid friction members
and the side frame column guides. In addition to the friction
members highly successful hydraulic snubbers, such as shown in U.S.
Pat. Nos. 4,004,525 and 3,868,912, which are vertically disposed in
a spring group, have been developed and provide an even more
effective means of snubbing the freight car swaying and bounce.
The utilization of rigid friction members for swaying has been
shown to be defective in several areas. For example: the steel on
steel frictional engagement between the rigid friction member and
the side frame column guide wear plate results in a "stick-slip"
friction action which produces poor ride quality. Furthermore, with
an empty car the transmissability of the "stick-slip" friction can
result in an excitation or coupling with any or all of the natural
frequencies of the railway car components; and the "stick-slip"
friction action results in an impacting type start and stop
movement of the bolster with respect to the side frames thus
leading to potential deleterious structural effect. Furthermore,
the friction forces on the mating faces of the rigid friction
member with respect to the side frame column guide and the bolster
pockets may result in a requirement for frequent replacement of
components and/or a renewal of wear surfaces. Still further, with
higher friction forces of some rigid friction members the railway
trucks occasionally have a tendency to sieze in a random lossenged
angle (i.e., truck going out of square and the wheel flanges take
an acute angle with respect to the guiding rail) thereby increasing
unsymmetrical wheel flange and/or tread wear.
By use of the elastomeric friction member of the present invention
the above problems are overcome, or in the least, greatly
alleviated. Specifically, the elastomeric friction members deform
initially before slipping with respect to the side frame column
guide wear plate. Further, (just as a pencil eraser drawn across a
rigid surface will initially deform, thereafter have portions slip
while other mating portions deform and thereafter slip in its
entirity) portions of the surface of the elastomeric friction
member will slip while other portions will initially deform. Thus
the transition of the elastomeric friction member from rest to
movement will be smooth and controlled. With an elastomer, such as
urethane there initially occurs motion without friction through the
deformation of the elastomer and then the friction breaks for a
very smooth transition. Furthermore, the relatively soft interface
of the elastomeric friction member with respect to the rigid mating
surfaces results in substantially less wear and failure due to
loosening of column wear plates and of adjacent components and
surfaces. Still further, the tendency to freeze in a loosenged
attitude is substantially reduced with elastomeric friction members
because of the characteristic shear flexibility of elastomers.
Thus by using elastomeric friction members, control of the various
loaded and empty railway freight car motion modes is much superior
than with the rigid friction members utilized heretofore.
Furthermore, the function of spring group hydraulic snubber
assemblies will complement the elastomeric friction members
resulting in a more nearly linear spring motion response to all
truck inputs with less total energy dissipation by the damping
combination and less energy transmission to the car body in both
loaded and empty operational modes. Still further, if desired, the
hydraulic snubbers, which have been found to be operative to
furnish more linear and optimum damping may be utilized as
substantially the sole snubbing means and the elastomeric friction
member will then serve the primary purpose of maintaining the
bolster to side frame fit-up relationship. In this latter instance
the force levels of the friction member with respect to the side
frame column can be reduced to more optimum friction levels along
with more optimum shear deformation constants.
An additional feature of the elastomeric friction members of the
present invention is that they offer a controlled lateral restraint
between the car body and truck which tends to increase the
threshold primary hunting speed. The shear resilience of the
elastomeric friction members is superior to the rigid friction
members utilized heretofore. Hunting in railway vehicles is the
unstable cyclic yawing of trucks and the resulting lateral
oscillation of the railway car vehicle and is of particular
significance when the car in traveling is an empty condition at
relatively high speeds; for example, in excess of 40 miles per
hour. The lateral track irregularities combined with conventional
coned wheel configurations results in one side of a wheel set
moving ahead of the other which in turn results in the flanges of
the wheels striking and rubbing against the rails first on one side
and then on the other thereby causing undesirable lateral body
oscillations and excessive truck component and rail wear. As the
wheel treads and flanges wear, the tread conicity becomes more
severe and the flange-rail clearance becomes larger thereby
resulting in even greater excursions of the wheel sets during
hunting and hence a more severe response occurs at an even lower
speed. The lateral excursions can become effectively severe to
possibly result in derailments.
The inclusion of an elastmeric friction member of the present
invention provides a controlled lateral constraint by increasing
the lateral spring constant. The lateral spring constant of the
elastomer is added to the lateral spring constant of the spring
group, thus increasing the threshold hunting speed in much the same
manner as the elastomeric bearing blocks of the side bearing in
applicant's U.S. Pat. No. 4,080,016. For example, the resonance
frequency due to hunting with rigid friction member may be 11/2 to
2 hertz; however, the inclusion of the elastomeric friction members
of the present invention may drive this resonance frequency to 21/2
or 3 or even higher. Thus in some instances it may be possible to
adequately control hunting by the elastomeric friction members of
the present invention without the necessity of elastomeric bearing
blocks being disposed within the side bearings. In the least the
lateral spring constant provided by the elastomeric friction
members will permit a wider range of choices as to the composition
of the side bearing elastomeric bearing blocks.
A still further feature of the lateral constraint offered by the
elastomeric shear resilience of the elastomeric friction members of
the present invention is the elimination of the heretofore
relatively free lateral bolster movement between the bolster gibs.
This free movement resulted in the bolster gibs impacting with the
side frame columns at the lateral motion limits. The bolster gib
impact can cause additional response severity particularly in
rocking loaded cars as well as hunting empty cars.
Accordingly, it is one object of this invention to provide a
bolster to side frame friction assembly which provides smooth
transition and damping characteristics.
Another object of this invention is to provide a superior means of
fitting-up the side frame to bolster relationship.
Still another object of this invention is to provide a friction
assembly which does not cause excessive wear to adjacent surfaces
of the bolster and side frames.
Yet another object of this invention is to provide a side frame to
bolster friction assembly which, in addition to serving heretofore
"normal" functions of a friction member, additionally substantially
raises the threshold hunting speed of a railway truck assembly.
These and other objects and advantages of the present invention
will become more readily apparent upon a reading of the following
description and drawings in which:
FIG. 1 is a schematic plan view of a conventional railway truck
assembly of a type which will incorporate a load dependent friction
snubbing assembly of the present invention therein;
FIG. 2 is a fragmentary plan view taken on lines 2--2 of FIG. 3
which illustrates a typical spring group of a conventional railway
truck assembly;
FIG. 3 is a fragmentary side elvational view, partially in section,
of a bolster and side frame of a typical railway truck assembly
which includes therein a load dependent friction wedge assembly of
the prior art;
FIG. 4 is an enlarged partial side sectional view of a friction
assembly of the present invention in operational position on a
conventional railway truck assembly;
FIG. 5 is an enlarged partial side sectional view of another
embodiment of a friction assembly of the present invention in
operational position in a conventional railway truck assembly
having modified bolster ends;
FIG. 6 is an enlarged partial side sectional view of yet another
embodiment of a friction assembly of the present invention in
operational position in a conventional railway truck assembly
having modified bolster ends and wherein the friction assembly is
operative without the necessity of a biasing or preloading
spring;
FIG. 7 is an enlarged partial side elvational view of still another
embodiment of the present invention, similar to the embodiment of
FIG. 4; however, including heat dissipation means and lateral
captive restraints for the elastomeric friction member;
FIG. 8 is a plan view of the embodiment illustrated in FIG. 7;
and
FIGS. 7a and 8a are views respectively similar to FIGS. 7 and 8;
however, illustrating the deformed condition of the elastomeric
friction member.
FIGS. 1, 2 and 3 illustrate a standard four wheel railway freight
truck of a conventional design which is generally indicated at 10
and which comprises: bolster 16 extending transversely between a
pair of laterally spaced side frames 22; spring groups 20 seated on
each side frame 22 to support the bolster 16; and a centerplate 12
and suitable side bearings 14 which cooperate with the bolster 16
to support a carbody (not shown). A pair of spaced axle assemblies
24 having suitably journaled wheels 26 thereon extend in a
direction generally parallel to the longitudinal extent of bolster
16 and support each side frame 22 adjacent respective axial end
portions thereof and cooperate with a spaced pair of rails (not
shown) for the rolling movement of the truck 10 therealong.
FIG. 3 is illustrative of a typical rigid friction wedge 28 of the
prior art such as is shown in U.S. Pat. No. 3,461,815. Typically
prior rigid friction wedges such as wedge 28 are generally
triangular in cross-section with the hypotenuse mating with a
similarly inclined surface 30 of a pocket 32 formed in axial end
portions of the bolster 16. As shown there is a pair of
transversely spaced rigid friction wedges 28 at each end of the
bolster 16. The vertical surface 34 of each rigid wedge 28 is in
biased engagement with a vertically extending wear plate 36
positioned on an adjacent column guide 38 of the side frames 22.
This biased engagement is accomplished by pre-loading forces
created by a spring coil unit 40; which includes inner and outer
coils 42 and 44, respectively, extending vertically between the
side frame 22 and an underside surface of the rigid friction wedge
28. Coil units 40 are generally considered a part of the spring
group 20 with the balance of the coil units of spring group 20
communicating directly between the side frame 22 and the bolster
16.
As is known rigid friction wedges such as wedge 28 are utilized as
an engagement means between the otherwise relatively loose bolster
to side frame relationship of conventional trucks and which also
serves as a limited damping means for a degree of rocking or
swaying and bouncing control of the railway vehicle freight car
truck 10. However, as is described hereinbefore, rigid friction
wedges such as wedge 28 suffer from a variety of deficiencies such
as: rigid stick-slip friction action which can result in excitation
or coupling with the natural frequencies of railway car components
and deleterious structural effects; substantial wear on mating
surfaces; generally poor ride quality and a propensity to
contribute to flange and wheel wear. Furthermore, wedges of the
type illustrated in FIG. 3 are known to have but a limited effect
on the hunting response of an empty freight car.
At this point it is to be noted that the invention herein is
primarily directed to an improvement over the rigid bolster to side
frame friction wedges utilized heretofore and the operation and
cooperation of such improved arrangements with generally well known
railway freight car components. Accordingly, other than is
necessary to describe the various embodiments of the invention
herein with respect to the bolster and sideframe relationships, the
balance of the elements specified hereinabove need not be described
in detail for a full and complete understanding of this invention
to those skilled in the art. Furthermore, for purposes of
description hereinafter, inner or inwardly and outer or outwardly
shall respectively refer to towards and away from the longitudinal
axis of the bolster 16.
FIG. 4 illustrates a retrofit side frame to bolster friction
assembly 50 of the present invention which is of a configuration
which is adapted to be insertable within the bolster pocket 32 to
replace prior art rigid friction wedges, such as wedge 28, without
the need to alter the standard configuration of existing bolsters
16 and side frames 22 of the conventional freight car truck 10.
Friction assembly 50 comprises: an elastomeric friction member 52
and spring follower 54 which is biased into engagement with member
52 by means of the coil unit 40 which extends vertically between an
upwardly facing lower surface 56 of side frame 22 and downwardly
facing lower surface 58 of follower 54. Follower 54 has a genrally
upwardly extending triangular configuration and includes a
downwardly open keeper pocket 55 formed within surface 58 for the
captive retention of the upper end portion of coil unit 40. As
viewed in FIG. 4 friction member 52 comprises an an inwardly
projecting first portion, shown as formed triangular portion 62,
and an outer second portion, illustrated as a generally rectangular
portion 60.
With a general configuration as described above, when friction
assembly 50 is biased into the operational position thereof by coil
unit 40, the outer vertically extending surface 64 of portion 60
will be in biased engagement with the adjacent vertically extending
surface 66 of the column guide wear plate 38 and the lower sloping
surface 68 of triangular portion 62 will be in engagement with a
complementary sloping surface 70 of follower 54. Furthermore, the
upper sloping surface 72 of triangular portion 62 will be aligned
in a common sloping plane with inner sloping surface 74 of follower
54 and the aligned surfaces 72 and 74 will be in continuous
engagement with the adjacent inclined surface 30 of the bolster
pocket 32. Thus, the elastomeric friction member 52 will be
generally confined within the adjacent portions of the boundary
surfaces 66, 30 and 70; however, the areas of portion 60 adjacent
the upper and lower ends thereof will not be confined thereby
allowing spaces for the member 52 to deform in shear.
The confined fit of the elastomeric friction member 52 within the
bolster pocket 30 provides the fit-up of the side frame to bolster
relationship. The pre-load provided by the upwardly directed
biasing force of coil unit 40 provides the frictional force between
the member 52 and the wear plate 36 interface which is necessary
for vertical damping by friction assembly 50. The pre-load force on
wedge shaped member 54 yields a transverse component reflected to
and generating friction on the surface 68. This friction force may
be varied by varying the spring constant of the coil unit 40 or by
varying the "self-actuation angle". In the embodiment described,
the self-actuation angle for upward motion of bolster 16 is the
angle between surfaces 68 and 66 and for downward motion of bolster
16, the angle between surfaces 72 and 66. As the spring constant
increases or the self-actuation angle decreases or becomes more
acute the normal load on the wear plate surface 66 increases.
The normal force on the wear plate surface 66, in conjunction with
the coefficient of friction between surfaces 64 and 66 determines
the amount of external vertical force necessary to break friction
between the wear plate 38 and the elastomeric friction member 52.
Inasmuch as the damping from the vertical friction force to aid in
the prevention of excessive rocking or bouncing conditions of the
railway freight car 10 is dependent upon the biasing force of the
friction assembly 50, it is important that the pre-determined force
necessary to break friction not be so great as to prevent
substantially all vertical movement of the bolster 16. Similarly,
such pre-determined force must not be so small as to provide an
insignificant damping effect.
Through the use of the friction assembly 50 of this invention, the
damping of the vertical forces which would result in excessive
rocking or swaying of the railway freight truck assembly 10 is
accomplished in a smooth and controlled manner. Specifically, upon
initial movement of the bolster 16 with respect to the sideframes
22, the elastomeric friction member 52 deforms vertically (see
deformed member 52 as illustrated in the alternative embodiment of
FIG. 7a). After this initial deformation, portions of the friction
member 52 will continue deforming while other portions will slip
with respect to the adjacent wear plate 36. Finally, friction will
be entirely broken and the entire surface 64 of friction member 52
will slip with respect to the mating surface 66 of wear plate 38.
Thus, the transition of friction member 52 from stationary to
sliding is extrememly smooth and not at all like the abrupt
"stick-slip" action of the prior art rigid friction wedges, such as
the rigid friction wedge 28 discussed hereinbefore. Furthermore
during the entire transition from preliminary partial deformation,
deformation and partial sliding and complete sliding, the vertical
motion of the bolster 10 with respect to the sideframes 22 is
resisted by vertical bolster spring forces, including the coil
units 40, and the damping or friction forces that occur during
rocking or vertical bouncing. Still further, the physical
properties of the elastomeric material of friction member 52 are
such that the member 52 will not cause excessive wear, abrading or
galling of the mating metallic surfaces.
An additional and very important feature of the side frame to
bolster friction assembly 50 of the present invention is that it
offers a controlled bolster to side frame restraint. This increases
the threshold hunting speed and reduces the lateral bolster gib
impact for both rocking and hunting control. Insofar as hunting
control, the operation of the friction assembly 50 and the lateral
deformation characteristics of the elastomeric friction members 52
will be similar to the general operation and deformation
characteristics described heretofore with respect to the
elastomeric bearing blocks in the side bearings in U.S. Pat. Nos.
3,957,318 and 4,090,750. The primary distinction between such
patents and the present invention is that in such patents, the
elastomeric side bearing blocks inhibit hunting by restraining the
movement of the truck body with respect to the car body wherein in
the present invention, the elastomeric friction members 52 act to
control hunting by adding more restraint to the transverse or
horizontal movement of the bolster 16 with respect to the side
frames 22. Specifically, the elastomeric friction members 52 will
deform in shear in a plane which extends in the longitudinal
direction of the adjacent side frame 22 when the railway truck 10
is traveling at a high speed when there is a tendency for an empty
car to hunt and the bolster to oscillate in a horizontal plane. The
friction members 52 aid in the prevention of hunting by providing a
sufficiently rigid shearing constraint at the bolster ends within a
pre-determined acceptable modulus of elasticity while still
maintaining the ability of the members 52 to provide the side frame
to bolster fit-up effect and the vertical damping as discussed
hereinbefore. The alternative embodiment best illustrated in FIG.
8a insofar as the deformation of the elastomeric friction member 52
during hunting control additionally includes a formed depression in
the column guide wear plate to limit the lateral sliding of the
member 52.
The hunting control qualities of the friction assembly 50 may be
used in series with the hunting control aspects of the side
bearings described in the above mentioned U.S. Pat. Nos. 3,957,318
and 4,090,750 or, if conditions so dictate, the hunting control can
be accomplished primarily by the friction assembly 50 or by the
friction assembly 50 in conjunction with the transverse force
damping characteristics of the inclined snubber arrangement which
is illustrated in U.S. Pat. No. 4,132,176. In such later instances,
the requirement for elastomeric bearing blocks being disposed in
the side bearings may no longer be necessary for adequate hunting
control. In the former instance the utilization of a side bearing
block constructed of two differing materials may no longer be
required. In any event, the elastomeric material composition of the
elastomeric friction member 52 will vary substantially (i.e.
hardness characteristics, compression qualities, one or two
material composition and the like) depending on the design effect
desired and the synergism, if any, with other hunting control
components of the railway freight truck 10.
FIG. 5 illustrates another embodiment of a side frame to bolster
friction assembly 80 of the present invention wherein the axial end
portions 82 of a standard bolster 16 are custom designed to provide
rectangular pockets 84 for captively receiving the friction
assembly 80 therewithin. End portions 82 comprise: a top flange 86,
having the outer end thereof spaced slightly inwardly from wear
plate 36; a bottom flange 88 spaced downwardly from flange 86 and
having the outer end thereof spaced inwardly with respect to the
outer end of flange 86; and a web or wall portion 90 extending
vertically between flanges 86 and 88 adjacent the outermost end of
flange 88.
The bolster friction assembly 80 comprises: horizontally disposed
elastomeric friction member 92 having the upper and lower sides
thereof tapering inwardly from the outer ends thereof; a top keeper
member 94 having a planar upperside surface thereof in
communication with the underside surface of the top flange 86 and
having a downwardly sloping underside surface which is in
communication with an adjacent sloping side surface of friction
member 92; and a lower follower member 96 having an upwardly
sloping upperside surface which is in communication with an
adjacent sloping side surface of friction member 92. The entire
assembly 80 is provided with a pre-load or normal force by means of
the coil unit 40 which communicates between the surface 56 of side
frame 22 and the downwardly facing surface of lower follower member
96.
The operation and effect of friction assembly 80 is essentially the
same as the fit-up, rocking and bouncing control, and hunting
control as described hereinbefore with respect to friction assembly
50. The primary distinction between assemblies 80 and 50 are
structural and the operational effects dictated by these structural
distinctions. Specifically, the self-actuation angle of assembly 80
(as determined by the upper and lower sloping surfaces of friction
member 92) is less acute with respect to the wear plate surface 66
then the self-actuation angle of assembly 50. Accordingly, the
self-actuation force component normal to the wear plate surface 66
of assembly 80 for a given spring constant of coil unit 40, will be
less than the self-actuation force component of assembly 50.
However, it is to be noted that the degree of confinement of both
elastomeric friction members resulting in a static confinement
pressure on all faces surrounding the members is in addition to the
self-actuation force or pressure component that occured with
impending vertical motion. The selfactuation forces or pressure of
assembly 80 will be less than assembly 50, assuming a similar
composition elastomeric material used in each of the bearing
members. The self-actuation pressure not only increases with a more
acute angle but also with a softer durameter elastomer.
FIG. 6 illustrates still another embodiment of a side frame to
bolster friction assembly 100 of the present invention wherein the
axial end portions 102 of a standard bolster 16 are custom designed
to provide rectangular pockets 104 for captively receiving the
friction assembly 100 therewithin. Furthermore, friction assembly
100 is operative without the necessity of a coil unit 40 and the
normal force resulting in friction on the surface 116 is entirely
the result of the lateral confinement surrounding the elastomeric
friction member 114.
End portions 102 comprise: top and bottom vertically spaced flanges
106 and 108 respectively, which have outer ends thereof in a common
vertical plane (or a slightly inwardly sloping plane, if desired),
which plane is spaced slightly inwardly from the inner surface of
the wear plate 110; and a web or wall portion 112 inwardly spaced
from the outer ends of flanges 106 and 108 and extending vertically
between flanges 106 and 108.
The side frame to bolster friction assembly 100 comprises a
horizontally extending generally rectangular elastomeric friction
member 114 having the outermost end thereof engaging the innermost
surface 116 of the wear plate 110. Surface 116 slopes downwardly
and inwardly from the uppermost end thereof and acts as a wedging
force to compress the friction member 114 as the bolster 16 moves
downwardly with respect to the side frames 22. This compression of
friction member 114 by the increasing confinement of the wedging
action created by the sloping surface 116 will result in a
frictional restraint between the outer surface of member 114 and
surface 116. This frictional restraint through the use of an
elastomeric friction member will provide the operational advantages
discussed hereinbefore with respect to the fit-up of the bolster to
side frame relationship, hunting control and damping of rocking or
bouncing of the railway freight truck 10.
An obvious advantage should design criteria dictate the usage of an
assembly such as assembly 100 is that no coil units 40 are required
to provide a pre-load force. In such an instance the special coil
units 40 can be deleted and larger capacity bolster to side frame
spring coils can be substituted therefor. The upward bias of the
spring groups 20 will urge the bolster 16 upwardly after downward
movement thereof and, because pockets 104 engage both the upper and
lower surfaces of friction members 114, members 114 will return to
the upper positions thereof upon upward movement of the bolster
16.
FIGS. 7 and 8 illustrate yet another embodiment of a side frame to
bolster friction assembly 120 of the present investion which is
substantially identical in construction and operation to the
friction assembly 50 described hereinbefore with the primary
distinction therebetween being that friction assembly 120 is
operative in conjunction with a heat dissipation and wear surface
means 122 which is carried by side frames 22 at the column guides
38 rather than the basic wear plate 36. FIGS. 7(a) and 8(a)
illustrate the deformed condition of elastomeric friction member 52
as was discussed hereinbefore with reference to assembly 50.
Heat dissipation and wear surface means 122 comprises: a generally
vertically extending plate portion 124; a continuous vertically
extending guiding depression 126 on the inner surface 128 of the
plate portion 124; and a plurality of transversely spaced
vertically extending heat dissipation fins 130 which are integrally
formed with portion 124 and extend outwardly from the outer surface
thereof. A vertically extending formed opening 132 is provided
through the side frame column guides 38 for the reception of the
heat dissipation fins 130 therethrough when the means 126 is
secured in operational position. As shown, in FIGS. 8 and 8(a),
means 122 are releasably secured to column guides 38, such as by
bolts 134 or the like, which communicate between guides 38 and
plate portion 122 transversely outwardly adjacent the opening
132.
As is shown the balance of the elements of friction assembly 120
are essentially identical to the like numbered elements of assembly
50. Accordingly, the operation of assembly 120 will in most parts
be identical to the operation described with respect to assembly 50
except for the heat dissipation afforded by means 122 and the
lateral restraint provided by the depression 126. Insofar as the
lateral restraint it is noted that the transverse dimension of
depression 126 is substantially identical to the transverse
dimension of the elastomeric friction member 52. Thus the hunting
control offered by friction members 52 in assembly 120 is primarily
through the deflection of the friction members 52. The depression
126 prevents the member 52 from sliding transversely with respect
to the inner surace 128.
Insofar as the heat dissipation it is to be noted that the
elastomeric material of friction member 52 is an inherently
excellent heat insulator. Accordingly, the best build up at inner
surface 128 may be substantial under certain operating
circumstances; for example, 180.degree. F. or more. Conditions may
dictate that the elastomeric material of the friction member 52
adjacent the inner surface 58 be relatively stiff to resist wear
and also to provide substantial shear deflection characteristics.
As elastomeric material heats up substantially, the shear
deflection characteristics may lessen or become uncontrolled. If
design criteria dictates substantial shear deflection
characteristics, such an uncontrolled change in these
characteristics may be unacceptable. Accordingly, by providing the
finned arrangement of means 122, the heat will be drawn from the
inner surface 128 and dissipated to the surrounding atmosphere.
Furthermore, simply by providing the opening 132 to releasably
retain a wearing member, even one without heat dissipation fins
130, air can circulate closer to the inner surface and thus
dissipate the heat build up which normally occurs thereat.
The invention herein is primarily directed to a side frame to
bolster friction assembly having elastomeric friction means.
Accordingly, various changes can be made by those skilled in the
art to the embodiments described hereinabove without departing from
the scope of the invention herein, which is defined by the scope of
the claims hereinafter. For example: friction assembly 50, as well
as other assemblies described herein, may be formed as a single
elastomeric member rather than an independent elastomeric member 52
and a rigid follower 54; in all embodiments hydraulic snubbers can
be disposed in the spring groups 20 to aid in the control of
rocking or swaying of the railway freight truck 10; in all
embodiments the elastomeric members may be formed with one or more
differing layers of elastomer if conditions so dictate, the inner
surfaces of the wear plates may be lubricated for initial break-in
if desired; a guiding and keeper depression can be used in all
embodiments if desired; the elastomeric portions of the friction
member may be reduced if desired so long as sufficient shear
constraint and deformation characteristics remain and that the
interface at the column guide is an elastomeric material; and the
like.
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