Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACRGROIJND OF THE lNV~ ,lON
A railway freight car commonly includes a car body
supported on the center plates of a pair of longitudinally spaced
trucks. The coned wheels of the trucks engage the respective
rails of a railway track and the trucks travel a generally
sinuous path along tangent track as they continually seek a
centered position under the steering influence of the wheel
conicity. In traveling such a sinuous path, a railway truck will
oscillate laterally and yaw cyclically with respect to the car
body about the vertical axis defined by the vertical center line
of the truck bolster center plate. A railway truck also will yaw
or rotate quasi-statically with respect to the car body in
negotiating curved track.
As a result of such lateral truck oscillation and cyclic
yawing, unstable truck hunting responses can develop if the
frequency of the cyclic motion approaches resonance. Reference
is made hereby to prior U.S. patent 3,957,318 for further
detailed explanation of railway vehicle truck hunting phenomena.
Railway car body rock and roll is another problem in
railway car stability that is related to the truck hunting
phenomenon. As the trucks of a railway car negotiate their
sinuous path of travel along the railway track, the car body
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will move laterally in concert with the cyclic lateral
movement of the truck center plates. The loaded or heavy
car readily tolerates this lateral oscillation; however, the
empty or light car body may be driven to rock laterally from
side to side. As with known truck hunting phenomena, this
lateral rock and roll empty car body motion can also be
driven by resonant coupling to destructive extremes.
hailway truck side bearings have long been utilized to
provide support for a car body with respect to a truck
laterally outward ot the truck center plate. Such support
is necessary not only in view of the tendency of an empty
car body to roch from side to side as a result of the force
inputs of hunting or rock and roll phenomena, but
addi-tlonally by the negotiation of track curves and the
superclevated track encountered in curves.
~laer Conventional side bearings have included roller
bearings carried for rolling movement longitudinally wlthin
an elongated cage or carrier mounted on a railway truck
bolster. The roller extends above the uppermost extent of
the open top of the carrier for rolling engagement with a
wear plate carried by the car body. Such side bearings are
able to support a car body with respect to a truch bolster
laterally outward of the truck center plate while at the
same time permitting the bolster, and therefore the truck,
the freedom to rotate with respect to the car body as is
necessary to accommodate the normal truck movement along
3 204732~
both tangent and curved track as above described.
rhe art has also contemplated railway truch side
bearinys which serve not only to support a car body with
respect to a truck bolster during relative rotational
movemen-t therebetween, but in addition to dissipa-te energy
through frictional engagement between the car body wear
plate and a bearing element whereby the requisite rotational
freedom of the truck with respect to the car body is
malntained while a degree of restraint is also provided as a
means to control and limit destructive hunting responses.
Still further, the prior art has contemplated the use of
elastomeric elements to cushion the vertical loading of a
car body on a truck bolster exerted through the side bearing
struc-ture. Still other prior side bearings have
contemplated roller bearing structures with self-centering
rollers.
Among -the prior side bearlngs known in the art as
above characterized are those disclosed in U.S. paten-ts
1,831,926, 2,301,372, 2,754,768, 3,255,712, 3,295,463,
3,313,245, 3,493,221, 3,518,948, 3,556,503, 3,623,464,
3,670,661, 3,719,154, 3,796,167 and 4,859,089.
In some prior side bearings, the desired function was
purely to minimize friction, as in roller side bearings. In
others, friction elements were intentionally introduced to
provide both support and rotational freedom for th- car body
i ~ 2047324
with respect to the truck boIster, as well as rotational
restraint through the frictional dissipation of energy. The
above-cited patent 4,359,089 is one example of such an
energy dissipating side bearing.
Other more recent pr1or art side bearings such as that
disclosed in U.S. patent 4,090,750 have contemplated the use
of bearing elements formed of elastomeric columns and
upstanding rigid abutments which are engageable with a car
body wear plate to provide both vertical support and
relative rotational freedom for the car body with respect to
the bolster, as well as a friction interface between the
elastomeric columns and the car body wear plate to provide
frictional energy dissipation upon relative rotation of the
car body with respect to the bolster.
still other recent prior art side bearlngs such as
those disclosed in U.S. patent 4,0~0,016 and 3,957,31~,
combine elastomeric columns to provide support and
trlc~lonal energy dissipation as above characterized, and
rollcr elements to limit the magnitude of vertical
deflection of the elastomeric elements by providing a solid
stop beyond which the car body wear plate cannot move
vertically downward. The roller elements provide, at the
limit of vertical motion of the wear plate downward toward
the bolster, a range of relative rotational freedom for the
car body with respect to the bolster without significantly
increasing frictional restraint with greater side bearing
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oadirlg beyond that afforded by the elastomeric columns
alone.
Another truch bearing structure, not so recent, is
disclosed in U.S. patent 38,182 as a ball bearing element
disposed in a downwardly concave cup which is in turn
resiliently supported by an elastomeric ring element.
The present invention contemplates a novel and
lmproved rallway truch side bearing structure especially
well suited for use in railway truch and car body
comblnations unknown when many of the above cited prior
bearings were developed. Others of the above prior slde
bearings, although developed when the more modern truch and
car body combinations were known and could be suitably
adapted for use thereon, were nevertheless not specifically
developed for use with such truck and car body assemblies
and their design and development did not contemplate the
opera-ting conditions and problems posed by modern car
configurations.
More specifically, certain newer types of railway cars
utilize articulated couplings between pairs of adjacent car
platforms that share a common intermediate truck having a
f]at center plate bearing. These and other car
contlgurations often may have longer spacing between
adjacent trucks; that is, the car platform lengths, and
therefore the inter-truck spacing, may be groater than in
" ~ ~
~047~4
conventional cars. Stacking of containerized loads and
similar transport modes for these and other cars, often
characterized as intermodal cars, has resulted in loaded
cars with extremely high centers of gravity, for example as
much as 110 inches above the track.
In these and other car configurations, the role of the
side bearing in supporting the car body with respect to the
bolster has been altered dramatically. For example, in very
high center of gravity loaded cars, most particularly the
double stacked container configurations, the loaded car body
center of gravity is located well above the articulated
connector by which at least one end of the car body is
supported. Even if the opposed end of the car body is
supported by its own truck on a conventional flat center
plate bearing, and even if the lading is centered on the car
platform, the torsional stiffness of the car platform and
containerized lading may be insufficient to keep the car
body end that is supported in spherical bearing segments
from leaning continuously to one lateral side or the other
for relatively extended periods of car travel. If the
lading is off-center, or in such operational circumstances
as the traverse of track curves, extended periods of large
magnitude side bearing loading may be vir~tually unavoidable.
Accordingly, the corresponding side bearing may be required
to support a much greater than normal load through extended
periods of car travel. Thus, the side bearing must
accommodate controlled rotational freedom between the truck
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an~ the car body through an angle equivalent to the maximum
relative rotation therebetween, and this in turn requires
maximum longitudinal rolli*g freedom for the roller bearing
element. The maximum relative rotation between a car body
and a truck in normal operation may be as great as the
relative rotation experienced from a short radius left hand
turnout to a similarly short radiused right hand turnout,
although more typically the range of relative truch-to-car
body rotation which the side bearing must accommodate would
be that experienced in the spiral or entry portion of a
track curve.
~he extendea plattorm lengths of some modern cars also
can require a greater range of relative rotational freedom
be-tween the truck and the car platform because a longer
platform requires a greater angle of relative rotation
between the platform and the respective truchs to negotiate
curved trach of any given radius. Still further, wlth
greater car load capacities and higher centers of gravity
zo there is impetus for designers to place the side bearings at
a greater radius from the truck center plate or articulated
connector to maximize the lateral moment arm of the side
bearing with respect to the center plate bearing. This too
increases the magnitude of roller bearing movement needed to
accommodate relative truch-to-car body rotation. An
additional design problem is that the geometric limitations
of truck and car body design limit the physical size of the
side bearing components that can be utilized in a given
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.,
application. It is preferred under most circumstances to
keep the "footprint" of a side bearing (i.e. the size of the
car body wear plate required to cooperate with the side
bearing) as small as possible, even though modern car
designs often call for increased rather than reduced bearing
load capacity and range of movement.
BRIEF SU~MARY OF THE INVENTION
Ihe present invention contemplates an improved side
bearing structure which is especially well suited for use
with intermodal cars and similar modern car configurations
having large load capacities, high centers of gravity,
longer truch spacing, and other design features to which
some prior side bearings might be less well suited in the
task of optimizing the dynamic performance of the car. The
invention contemplates generally a railway truck side
bearing assembly which is preferably adapted to be confined
within a generally conventional, standard railway truck side
bearing housing or carrier and including at least one
upstanding elastomeric bearing element and a longitudinally
adjacent spacer member disposed within the carrier. The
spacer member includes at least one upstanding abutment
which longitudinally confines a corresponding elastomeric
column, and a gensrally upwardly facing elongated surface to
receive a rigid bearing element such as a roller therein.
The roller is provided a range of free rolling movement
longitudinally of the spacer member between stops or limits
~04732~ `
defined by longitudinally spaced portions of the spacer
member.
The range of free movement for the roller can be made -
sufficient to accommodate the greater range of relative
rotary movement between a bolster and a car platform
required in modern car configurations as discussed
hereinabove without sacrifice of frictional energy
dissipation capability provided by the elastomeric columns.
This is so in part because the upstanding abutments of the
spacer member can extend upwardly above the uppermost extent of
the bearing carrier or housing and adjacent an upper portion
of a corresponding elastomeric column to longitudinally
~ buttress and confine the elastomeric element sufficien-tly
! 15 that it does not bend longitudinally over the top of the
confining abutment.
Accordingly, surface contact between the upwardly
facing bearing surface of the elastomeric column and the car
body wear plate is maintained more uniformly and the full
benefi.t of the shear restraint and frictional energy
dissipation at the elastomer-to-rigid wear plate interface
thus is realized. As a result, a smaller section thichness
of elastomer, especially in the longitudinal direction, may
2~ be employed to attain the same levels of performance as
regards shear restraint as in prior elastomeric side
bearings requiring larger section elastomeric columns.
Thus, without sacrificing the desirable control capabilities
10 2047324
of a larger section elastomeric column, an increased range of
longitudinal roller motion is made available in a side bearing
housing of given dimensions.
Generally speaking, the present invention may therefore
be considered as providing in a railway vehicle side bearing
having a rigid elongated housing which is adapted to be carried
by a railway truck to support a railway car body with the housing
having laterally spaced, upwardly projecting side walls and
longitudinally spaced, upwardly projecting end walls with
respective uppermost edges, such side and end walls enclosing an
upwardly open elongated cavity, a bearing assembly adapted to be
received within such cavity for engagement with a wear plate
carried by such railway car body comprising: compliant bearing
means adapted to be disposed within such cavity; the compliant
bearing means including a pair of upstanding, resiliently
deformable elastomeric elements disposed adjacent one another
with one of the elastomeric bearing elements being adapted to be
disposed adjacent one of such end walls; each elastomeric bearing
element having a generally upwardly facing surface portion; the
compliant bearing means further including a unitary rigid
friction element which is engageable with the upwardly facing
surface portions and extends upwardly therefrom; the rigid
friction element having a bearing surface means adapted to be
disposed vertically above such uppermost edges for frictional
engagement with such wear plate; a rigid, elongated spacer means
adapted to be disposed within such cavity adjacent the other of
the elastomeric elements; the spacer means including an upwardly
facing surface means extending thereon, and an upstanding
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lOa ~0473 24
abutment means which is cooperable with at least some of such
walls to confine the elastomeric bearing elements within such
cavity; rigid bearing means supported upon the surface means and
being moveable thereon in opposed directions within predetermined
limits; the rigid bearing means being of an overall vertical
height that, when supported upon the surface means with the
spacer means disposed within such cavity, the rigid bearing means
has an Uppermost extent located above such uppermost edges of
such side and end walls; the elastomeric elements being
vertically deformable in compression and having an overall
vertical height when disposed in assembly with the rigid friction
element within such cavity that the bearing surface means of the
rigid friction element is disposed vertically above the uppermost
extent of the rigid bearing means to maintain a vertical spacing
between the rigid bearing means and such wear plate throughout
a range of vertically downwardly directed loadings applied to the
compliant bearing means by engagement of the bearing surface
means with such wear plate, and to permit such wear plate to
engage the rigid bearing means when the vertically downwardly
directed loading on the compliant bearing means equals a given
load; and the abutment means extending vertically adjacent the
other of the elastomeric bearing elements to an uppermost
elevation intermediate the uppermost edges of such side and end
walls and the uppermost extent of the rigid bearing means.
These and other features and further advantages of the
invention will be more fully appreciated upon consideration of
the following detailed description and the accompanying
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11 2~324
drawings in which:
Fig. 1 is an end elevation showing a side bearing
according to one presently preferred embodiment of the
instant invention and cooperatihg portions of a railway
truck and car body;
Fig. 2 is a sectioned side elevation of a side bearing
taken on line 2-2 of Fig. 1;
1 0
~ig. 3 is a sectioned side elevation showing an
alternative embodiment of the instant invention;
fig. 4 is a sectioned side elevation showing another
alternative embodiment of the instant invention;
,
Fig. 5 is a sectioned side elevation showing still
another alternative embodiment of the inventionj
Fig. 6 is a sectioned side elevation similar to Fig. 5
and including representation of a car body wear plate to
illustrate one operating condition for the illustrated side
bearing;
Fig. 7 is a top plan view of another alternative
embodiment of the invention;
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12
Flg. 8 lS a sectioned side elevation taken on line
VIII-VIII of Fig. 7;
Fig. 9 lS a top plan view of a further alternative
embodiment of the invention;
Fig. 10 is a side elevation, partially broken away, of
still another alternative embodiment of the invention;
Fig. 11 is a top plan view of the embodiment of Fig. 10
with portions brohen away;
Fig. 12 is a sectioned side elevation of another
alternative embodiment of the invention;
Fig. 13 lS a sectioned side elevation of another
alternative embodiment of the invention;
~ig. l4 is a sectioned side elevation of a fragmentary
portion of a side bearing showing a further alternative
embodiment of the invention; and
Fig. 15 is a sectioned side elevation similar to Fig. 14
showing yet another alternative embodiment of the invention.
~here is generally indicated at 10 in Figs. 1 and 2 a
side bearing assembly which is carried atop a bolster 12 of
a railway truck and is secured thereto as by threaded
fasteners 14 for cooperative interaction with the wear plate
13 ~0~7324
16 of a rail car body 18 supported by a center plate bearing
portion 13 of bolster 12. Although this invention will be
described with reference to a conventional truck bolster and
center plate support system as in a known three piece truck,
it will be understood that the invention may also be utiliz~d
in other car body support applications such as intermodal
cars or other car configurations where adjacent car platforms
are supported through the bearing segments, commonly
spherical in form, of an articulated coupling that is
supported on a truck, as well as alternative truck
configurations such as single axle trucks. For application
in a conventional three piece truck, other known components
not shown include spring groups mounted in a pair of side
frames to support the opposed longitudinal ends of bolster
12, and suitably journaled wheelsets which rest on tracks or
rails to support each side frame of the truck.
The invention herein is directed primarily to side
bearing assemblies such as shown at 10, and the balance of
the truck and car body elements set forth hereinabove are
well known in the art. Further detailed description of such
elements thus is not necessary for understanding of the
present invention.
The invention also contemplates in one preferred
embodiment an assembly of side bearing components adapted to
be received within a side bearing housing or carrier 20 of
generally conventional design, or alternatively in a new and
heretofore unknown side bearing carrier. The side bearing
assembly 10 comprises the elongated bearing carrier or
housing 20 having a pair of elongated, upstanding, laterally
spaced side walls 22 and a pair of longitudinally spaced,
upstanding end walls 24 which may be comprised of respective
pairs of laterally
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adjacent, inturned end flange portions of side walls 22.
For this and other bearing carrier end wall configurations,
shim plates 26 may be assembled with end wall portions Z4
such that upper portions 28 thereof overlie the uppermost
extent of end wall portions 24, and a lower extent 30 of
each shim plate Z6 extends adjacent an inner surface of the
end wall portions 24, respectively, and downwardly into the
confines of carrier 20.
i
The carrier 20 further includes a longitudinally and
laterally extending base portion 32 which, in conjunction
with side walls 2Z and end walls 24, forms an upwardly
opening cavity 34 to receive and confine an assembly of side
bearing elements.
It will be seen that side walls 22 and end walls 24
project upwardly to an uppermost extent which is at a
uniform elevation. Additionally, the upper extent 28 of
each shim plate 26 projects to an elevation above the
uppermost extent 36 of the side and end walls 22, 24 for a,
purpose to be described hereinbelow.
Within the confines of space 34 is received an
assembly of bearing elements comprised preferably of a pair
of elongated, upstanding elastomeric columns 40, one
received in each longitudinal end of space 34 adjacent a
respective end wall portion 24 and in longitudinal abutment
with the respective shim plate 26, an elongated spacer or
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-15-
abutment member 42 received within space 34 longitudinally~
intermediate elastomeric columns 40, and a rigid bearing
member such as a roller 44 is received within space 34
intermediate side walls 22 and within the conflnement of an
upwardly opening concavity 46 formed by abutment member 42.
Spacer member 42, also referred to alternatively as a
saddle, includes a longitudinally extendlng base portion 48
which rests upon an upper surface 50 of carrier base portion
, 10 32, a pair of upstanding end abutment portions 52 which are
; spaced longitudinally apart to reside longitudinally
inwardly adjacen. the respective elastomeric columns 40, and
integral curved or radiused portlons 54 which extend
intermediate base portion 48 and the respective abutment
portions 52.
It ~ill be noted that abutment portions 52 extend
upwardly to an uppermost extent 56 which, like the uppermost
portions 28 of shim plates 26, project above the upper
extent 36 of the side walls 22 and end walls 24 to an elevation
preferably just slightly below the highest elevation of
roller 44. Accordingly, upstanding abutments are provided
at an elevation above the highest lateral abutment provided
by carrier 20 such that the relative rotational movement
between bolster 12 and car body 18 occurs at all load lcvels
with reduced tendency for elastomeric columns 40 to bend
longitudinally, and therefore reduced tendency for
development of non-uniform loading of the elastomeric
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-16-
columns 40 in compression. More particularly, rulative
rotation between car body 18 and bolster 12 results at all
load levels in shear deformation of elastomeric columns 40
in the longitudinal direction and ultimate friction break
and longitudinal sliding of wear plate 16 on the uppermost
surfaces 41 of elastomeric columns 40. Both the control
provided by horizontal shear deformation of the elastomeric
columns prior to frictional sliding between surfaces 41 and
wear plate 16, and the energy dissipation achieved by
fric-tional sliding movement between the surfaces 41 and
plate 16 are optimized in part by abutments 52 which
constrain the elastomeric columns 40 to remain essentially
upright under all operating conditions and load levels.
In prior side bearings wherein a relatively elongated
extent of an elastomeric column projected above the highest
longitudinal abutments and was therefore relatively
uncor-fined in at least one longitudinal direction, relative
rotation of the bolster about a vertical axis with respect
to the car body, with the car body wear plate engaging the
side bearing elastomeric columns,
produced in the longitudinally unconfined elastomeric
columns a tendency to bend longitudinally. This is
especially true of the trailing or rearward elastomeric
~ column, reckoned with respect to the direction of
longitudinal movement of the car body wear plate 16 with
respect to the side bearing assembly. Such elastomer column
bending produces non-uniform loading across the surface 41
of the elastomeric element thereby significantly~degrading
the shear restraint available at the wear plate-to-ela~stomer
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17
int~rface. By providing abutments projecting upwardly, pre-
ferably above the bearing carrier side and end walls, and
especially for the
longitudinally opposed sides of the elastomeric element,
improved longitudinal confinement of the elastomeric element
enhar)ces the uniformity of loading on the uppermost surface
thereof. As a result, the shear restraint available at the
wear plate-to-elastomer interface is of both greater
magnitude and improved uniformity over that available
without such longitudinal abutments.
Ac~ordingly, the desired characteristics of shear
restraint in the elastomer-to-wear plate interface can be
achieved with elastomeric columns of smaller cross section
than required in prior side bearings. Therefore, within the
confines of a given bearing carrier 20 more longitudinal
space is available between elastomeric elements 40 by use of
smaller section elastomeric elements to provide a greater
longi-tudinal rolling range for roller 44. The side bearing
thus can accommodate increased angular rotation between
truck 12 and car body 18.
rhe lnwardly facing surfaces 60 of member 4~ provide
rigid stops or limits for roller movement such that roller
44 will not laterally deform elastomeric elements 40 as it
rolls longitudinally to one extreme or the other in its
longitudinal travel. However, it will be noted that the
spacer member 48 is free to move or rock longitudinally with
respect to housing 20 so that when roller 44 engages one of
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,'
-18-
surfaces 60, the member 48 can roll or tilt slightly in the
same longitudinal direction by limited longitudinal
compression of the adjacent elastomeric column 40. The
member 48 thereby provides a further increment of roller
movement in the longitudinal direction and cushions the
engagement of the roller on the surface 60.
It wlll be noted that the uppermost extent of roller
44 projects above the uppermost extent of the side walls 22
and end walls 24, and additionally above the uppermost
extent of the shim plate upper ends 28. The roller 44 also
projects above the uppermost projection 56 of the abutment
portions 52, although preferably only very slightly above.
Accordingly, when the loading on elastomeric columns 40
deforms them in vertical compression to the solid condition
whereat plate 16 engages roller 44, plate 16 remains at all
times clear of contact with side walls 22, end wall.s 24,
shim plates 26 and abutment projections 56, and only a very
minimal vertical extent of the elastomeric columns projects
above the uppermost extent 56 of abutments 52.
;
Inasmuch as one object of this invention is to
provide, within the confines of a given bearing carrier, the
necessary longitudinal free rolling range for a roller
bearing element to accommodate the greater relative
rotational movement between a truck and a car platform as
mus-t be accommodated in some modern cars, it will be noted
tha-t an additional advantage provided by abutment member 48
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- 1 9-
is that it elevates the rolling surface on which roller 44
is supported above the uppermost surface 50 of base 32.
Accordingly, the uppermost extent of roller 44 projects
further upward by an equal increment thereby permitting the
use of a smaller diameter roller than could be otherwise
employed, where the load limits to be encountered by the
roller bearing permit. A smaller diameter roller occupies
less of the longitudinal rolling range available between the
limi-ts defined by the abutment member 4~ thereby providing
further increased longitudinal free rolling range for the
roller 44. Accordingly, the smaller diameter roller allows
the accommodation of larger ranges of relative angular
rotation between a truck and a car body within the confines
of a given side bearing carrier or housing 20.
~ther embodiments of the lnvention are shown in figs.
3 through 5. In Fig. 3 the bearing assembly shown is
essentially identical in most salient respects to that
described hereinabove with reference to Figs. 1 and 2;
z~ however, the abutment member 62 is configured to include a
base portion 64 which is of a concave configuration to
provide a generally concave upper surface 66 on which roller
44 is supported. The roller 44 thus tends to be
gravitationally self-centering when in a free rolling state
(i.e. not engaged by the car body wear plate) to ensure that
sufficient free rolling range in either longitudinal
direc-tion will be available upon contact of the roller 44 by
the car body wear plate. It will be recalled that some
~_ 2047324
.
-20-
modern cars with extremely high centers of gravity when
loaded will tend to lean over on one or the other of side
bearings on a given truck for relatively long periods of
travel. For any embodiment of this invention, the available
free rolling space in either longitudinal direction for
roller 44, when centered, should be sufficient to
accommodate the maximum relative truck to car body rotation
which can occur under such circumstances.
A~dltionally, abutment member 62 is free to roch
longi-tudinally within housing 68 if the concave upper
surtace 73 on which member 62 rests is of a larger radius
than the mating convex surface 75 of member 62. As member
62 rocks, the upstanding abutment at the leading end thereof
(with respect to the direction of its longitudinal rocking)
compresses the corresponding elastomeric element 40. The
rocking action of member 62 presents to the roller a
progressively lower angle of inclination on surface 66 as
the roller 44 moves up the incline of surface 66 when
displaced from its centered position. Without the rocking
capability for member 62, as the roller moves to one side or
the other from its centered position it rolls up the
cen-tering incline, and the side bearing thus is lifting the
entire weight supported thereon vertically upward. This
increase in the vertical loading on the side bearing roller,
increases the directly proportional horizontal restraint
between the roller and body plate 16, which is undesirable;
however, such lifting reduces elastomer compression
!
'
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~_~ 21
housing 68 beneath the abutment member 6Z.
Fig. 4 discloses another alternative embodiment of the
invention similar in many salient respects to that described
with reference to Figs. 1 and 2, but having an abutment
member 76 with an elongated, essentially flat base portion
78 and upstanding portions 80 with the integral corner
portions joining abutments 80 to base 78 being of
significantly smaller radius than portions 54 of Fig. 2. In
addition to a slightly concave upper surface of base portion
78, centering of the roller 44 may be provided by biasing
elements 82 which are engageable with opposed lower surface
portions 84 of the roller 44 and ~lso engageable with inner
surfaces 86 of abutment member 76 adjacent the lower corners
thereof. Biased retainers 32 may be of solid, soft
elastomer construction, and preferably are formed to leave a
corner void 83 into which they may deform when contacted by
roller 44.
~ig. 5 illustrates yet another embodlmen-t Or the
inven-tion in which the entire cavity within the side and end
walls of a side bearing carrier or housing is occupied by an
enlarged upstanding elastomeric column 8~ and an
asymmetrical abutment member 90 having an upwardly concave
recess in which there is received a roller 44. Accordingly,
abutment member 90 includes a base portion 92 and a single
upstanding abutment portion 94 which extends upwardly
adjacent the longitudinally inner side of elastomeric column
2047324
22
for longitudinal confinement of the same. The opposed
end 96 of abutment member 90 interfaces with the end wall
portions 24 of the bearing carrier thereby serving to
position the abutment member 90 and provide a reaction
interface to bear the longitudinal forces imposed upon
abutment member 90 by confinement of elastomeric member ~8
in operation. End portion 96 together with upstanding
abutment 94 and connecting base portion 92 define an
upwardly opening recess 98 within which roller 44 is free
rolling between longitudinal limits in much the same manner
as above described with reference to other embodiments. In
addition, it is noted that the base portion 92 is of
increased thickness thus illustrating another means for
elevating roller 44 to thereby permit the use of a smaller
diameter roller, with the attendant benefits as hereinabove
described.
Additional embodiments and aspects of the invention are
illustrated by Figs. 6 to 15. Fig. 6 shows a side bearing
similar to that shown in Fig. 5 and mounted on a truck bolster
101. Fig. 6 also includes a generally schematic representation
of a car body wear plate 100 which is carried by a structural
member 102 that is rigidly affixed with respect to a railway car
body or platform (not shown). In Fig. 6, the side bearing
roller 44 is shown residing at one extreme position with respect
to spacer or abutment member 90 and spaced a near maximum
longitudinal distance from a compliant bearing means shown as an
elastomeric element 88.
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23
As noted hereinabove, one favorable aspect of the
embodiment of Fig. 5 is that it allows use of a minimum-length
wear plate. The wear plate which engages a side bearing must
always be provided with a bearing surface area and dimensions to
maintain proper bearing contact with the truck side bearing
throughout the entire range of relative motion between the side
bearing and the wear plate. In the case of prior side bearings
with elastomeric bearing elements, the length of the car body
wear plate had to be sufficient to maintain full coverage
contact with the entire upper surface area of both of the
elastomeric elements throughout the entire range of relative
movement between the car body and the truck bolster.
Prior elastomeric side bearings, when they have included a
separate rigid stop such as a rocker or a roller, typically have
included a pair of longitudinally spaced elastomeric bearing
elements with the rigid stop disposed therebetween. As it has
been essential to maintain full coverage contact of the wear
plate on the elastomeric bearing element engagement surfaces,
the required length of the wear plate has been considerably
greater than would be otherwise desirable.
The asymmetrical bearing structure of F;gs. 5 and 6,
having only a single elastomeric element and a solid stop such
as the roller 44 disposed adjacent thereto, permits use of a
much shorter wear plate. While the wear plate must still
maintain full coverage of the upper bearing surface 104 of
elastomeric element 88, there is no second elastomeric element
spaced from the element 88 to impose a similar coverage or
surface engagement requirement at a location spaced from
2~473~4
24
elastomeric element 88. Instead, the only other requirement for
bearing surface engagement is that the wear plate 100 be capable
of engaging roller 44 in load bearing engagement throughout the
available range of relative movement between the car body and
the truck bolster 101, and throughout the available range of
rolling movement for roller 44 with respect to abutment member
90 .
I, ~
As shown in Fig. 6, even with roller 44 at the extreme
position spaced as far as possible from elastomeric element
bearing element 88, the high point of the roller top 106, which
is the load bearing surface of roller 44, defines the furthest
extent to which the adjacent end portion 108 of wear plate 100
must reach. So long as at least the end portion 108 of wear
plate 100 overlies the bearing surface 106 of roller 44, load
bearing engagement may be maintained therebetween.
Thus It will be appreciated that since the load bearing
surface portion of the roller does not extend throughout the
longitudinal extent of the roller structure, but rather is
centered with respect to it, the wear plate 100 need not extend
to overlie the entire longitudinal extent of roller 44. That
is, essentially half of roller 44 may lie outboard of the
longitudinal reach of wear plate 100 since that portion of the
roller 44 is never engaged by the wear plate 100. As a result,
the required wear plate length is minimized.
Figs. 7 and 8 show another embodiment of the invention
which may be regarded as somewhat similar in structure to the
embodiments of Figs. 2 or 3, but with side bearing assembly 10
2n473~4
turned by 900 with respect to its orientation in the Fig. 2 and
3 embodiments. The free rolling rigid element, however, retains
a rolling orientation generally tangent to truck rotation. More
specifically, the side bearing 110 of Figs. 7 and 8 is moun.ted
on a truck bolster 101 and includes a carrier or cage such as a
unitary cast cage member 112 with integral mounting lug portions
114 and a perimeter wall structure including end walls 116 and
side walls 118. The cage 112 also includes integral interior
partitions 120 spaced from each other and from side walls 118 to
define three cavities 1Z2, 124, and 126 for receiving bearing
elements therein.
rhe lntermediate cavity 124 is dimensioned in accordance
with the above disclosure regarding other embodiments to receive
roller 44 for free rolling of roller 44 therein between
predetermined limits in the longitudinal direction, that is
longitudinally with respect to a car body as above disclosed.
Cavities 122 and 126 are spaced laterally to either side of
cavity 124 and are dimensioned to receive and confine
elastomeric bearing elements 128 for engagement with a wear
plate 130 carried by a support structure 132 of a car body (not
shown).
In this embodiment of the invention, the restraint
characteristics provided by the elastomeric element and roller
combination will be quite similar to those achieved with other
embodiments of the side bearing above described; however, in the
Fig. 7 and 8 embodiment, the elastomeric and rigid bearing
elements are spaced apart in the lateral direction rather than
~4~32~
26
in the longitudinal direction. Accordingly, this arrangement
also serves to permit optimization of wear plate dimensions by
reducing the longitudinal extent of the side bearing footprint,
and thus the required wear plate length. As will be explained
further herelnbelow, optimization of wear plate dimensions is
generally desirable, but minimizing wear plate length in
particular may be regarded as one of the more important
optimization parameters.
Althoug~ the side bearing em~odiments disclosed herein
generally may be suitable for use in an orientation with the
roller axis disposed radially with respect to the bolster center
plate center, the embodiment of Figs. 7 and 8 in particular is
well adapted for use in such a radial configuration. Radial
positioning of the side bearing affords a further opportunity to
minimize the length and width of the car body wear plate.
Fig. 9 shows a modification of the Fig. 7 and 8 embodiment
as an asymmetrical bearing structure similar in some respects to
the Fig. ~ and 6 embodiments but with the`roller turned 900 from
the roller orientation shown in Figs. 5 and 6, so that the
roller rolls along side a single elastomeric bearing element
rather than toward and away from it. More specifically, the
Fig. 9 embodiment includes a cage or carrier 130 with mounting
lugs 132 for mounting thereof on a truck bolster. A perimeter
wall structure 134 includeo end wall portions 136 and side wall
portions 138. An intermediate partition 140 divides the
interior space within the bounds of the perimeter wall structure
134 into laterally adjacent cavities 142 and 144. A roller 44
20~7324
27
is disposed for free rolling within limits in cavity 142 in the
direction longitudinally of the side bearing and laterally
adjacent to an elastomeric bearing element 1Z8 which is received
and confined within cavity 144.
~ he fig. 9 embodiment, lihe that of Figs. 7 and 8, permits
another mode of wear plate size optimization. Specifically, the
side bearing of Fig. 9 permits the longitudinal extent of the
wear plate to be minimized, and in addition permits its lateral
extent to be reduced further over that required by the Fig. 7
and 8 embodiment. Like the Fig. 7 and 8 embodiment, the side
bearing of Fig. 9 can also be oriented in a radial position with
respect to the truck center plate to minimize both the length
and width of the car body wear plate. Also, it may be oriented
on the truck bolster with the elastomeric column either inboard
or outboard of the roller element.
figs. 10 and 11 disclose another asymmetrical side bearing
having a single elastomeric element and a rigid stop such as a
roller element disposed adjacent one another within a fabrlcated
cage. More specifically, in Figs. 10 and 11 a cage member 146
may be formed by forming processes similar to those employed in
the fabrication of conventional side bearing cages or carriers
to include upstanding lateral side walls 148 and inturned
longitudinal ends 150. In addition, intermediate the
longitudinal ends of the carrier, a portion of each side wall 48
may be inturned at longitudinally adjacent locations 152 to
divide the area within the confines of the carrier side and end
walls into longitudinally adjacent cavities 154 and 156. An
elastomeric bearing element 158 is received in cavity 156 and a
2 ~
28
rigid bearing element such as a roller 160 is received
longltudinally adjacent thereto within cavity 152 for free
rolliny within llmits longitudinally of the carrier 156 toward
and away from elastomeric bearing element 158.
As in all of the above described embodiments,
elastomeric element 158 is provided with longitudinally spaced
high buttresses or abutments, the buttresses in this case being
in the form of conventional shim plates 162 shown in side
elevation in Fig. 10 and in plan view, partially broken away, in
Fig. 11. These high-reaching buttress elements confine upper
portions of the elastomeric element in the longitudinal
direction to maintain more uniform engagement of the bearing
element with a wear plate throughout relative motion
therebetween under all levels of vertical loading. Of course,
as in the above described embodiments, the uppermost extent of
shim plates 162 is in any event lower than the uppermost extent
of roller 160 so that the wear plate never engages the shim
plates 16Z.
rhe Fig. 10 and 11 embodiment also discloses structure by
means of which the desirable high-reaching buttressing for the
elastomeric element may be achieved while maintaining use of a
larger diameter roller than is used in other above described
embodiments. Specifically, the Fig. 10 and 11 embodiments do
not require any saddle or carrier member for the roller 160 such
as disclosed in the Fig. 2 to 5 embodiments, for oxa~ple.
Accordingly, the base surface 164 on which roller 160 rolls i5
at a lower elevation than the corresponding surface in the Fig.
2 to 5 embodiments. As a result, a larger diameter roller may
be utilized.
20~7324
29
Ot course it will be appreciated that use of a larger
diameter roller in a given longitudinal space envelope reduces
the available rolling range for the roller. Accordingly, to
maintain a desired rolling range in a side bearing of the Fig.
10 and 11 embodiment, it may be necessary to extend cage 46,
depending upon the diameter of the roller to be used, in order
to provide the desired rolling range. However, despite the
longer cage length, the Fig. 10 embodiment will still
accommodate a shorter car body wear plate than will prior side
lO bearing designs, due to the benefit of the asymmetrical side
bearing arrangement as discussed above.
I-t may be determined in some circumstances that the
benefit of a larger roller outweighs the desirability of a long
rolling range within the bearing cage. Accordingly, the option
provided by the instant invention of choosing a larger or a
smaller roller is another example of the way in which the
invention allows optimization of the side bearing and wear plate
footprint.
ln ~ig. 1~ a further embodiment of the invention is
20 disclosed as a side bearing 164 comprised of an elongated cage
or carrier 166 which may be fabricated by conventional means to
" include upstanding, longitudinally extending side walls 168 and
inturned end portions 170 which are adapted to receive shim
plates 172. A saddle member 174, which may be similar to that
described with reference to Fig. 5, is disposed within a cavity
176 defined within the confines of the side walls 168 and
inturned ends 170 of carrier 166. Saddle 174 is located
adjacent one longitudinal end of carrier 166 and includes a
downwardly concave upper surface 178 on which a roller 180 is
30 received for free rolling thereon within longitudinal limits.
2B~732~
A longitudinal end 182 of saddle 174 extends upwardly to
form a high-reaching buttress to confine between itself and the
opposed end of carrier 166 a compliant bearing means which
includes a pair of longitudinally adjacent elastomeric bearing
elements 184 and a rigid, unitary bearing element 186 disposed
atop the elastomeric bearing elements 184 and having an upper
surface 188 which is adapted to engage a car body wear plate
(not shown).
Tne elastomeric elements 184 are confined laterally by
side walls 176 and longitudinally by shim plate 172 (also
referred to as an end plate) and high-reaching buttress 182. In
addition, the upper surfaces 190 of elastomeric bearing elements
184 which engage corresponding lower surface portions 192 of
rigid bearing element 186 preferably are inclined with respect
to the horizontal so as to converge downwardly. Accordingly,
vertical loads applied through a car body wear plate to rigid
bearing element 186 act through the interface between surfaces
190 and 192 to urge the elastomeric bearing elements apart in
longitudinally opposed directions thereby maintaining uniform
location of the bearing elements 184 within carrier 166 in all-
modes of bearing operation. In addition, the tendency of
vertical loads to urge bearing elements 184 longitudinally apart
automatically takes up any slack or free motion of the
elastomeric portion of the Fig. 12 side bearing assembly such as
might result from progressive bearing wear or variation of
component dimensions within manufacturing tolerances. The
resulting confinement of the elastomeric elements 184 provides
for a uniform and consistent restraint characteristic.
2047324
31
Other features of the Fig. 12 embodiment include
interlocking tongue portions 189 of rigid element 186 which
project vertically downward into cooperating recesses formed in
the upper surfaces 190 of the elastomeric elements 184.
Interengagement of the tongues and recesses serves not only to
interlock the rigid element 186 to elastomeric elements 184, but
additionally to carry laterally directed forces between the
rigid element 186 and elastomeric elements 184 in part by
lateral compression of the elastomeric elements 184 between the
l0 tongues 189 and the sidewalls of the bearing carrier.
Additionally, the angle of inclination for surfaces 190
may be steeper than that for surfaces 192 so that vertical
compression of the elastomeric columns 184 is maintained as a
uniform percentage of the overall elastomeric column height
across the entire elastomeric column horizontal cross section.
Fig. 13 shows a further example of a side bearing
' according to the instant invention wherein the bearing carrier
or cage 192 lS cast as a unitary member to include the mounting
lugs or similar mounting structure, an elastomeric bearing
20 element receiving cavity, a roller element receiving cavity, a
free rolling range for the roller within the roller receiving
cavity, high reaching longitudinal buttress portions to confine
the elastomeric bearing element, and other structural elements
corresponding to features of the embodiments above described,
including an integral roller saddle portion with a high
elevation floor or base to permit utilization of a smaller
diameter roller.
32 ~732~
Figs. 14 and 15 show fragmentary portions of a side
bearing similar to that shown in Fig. 13 but including a rocker
element instead of a roller as a rigid or solid stop. As ha1s
been noted hereinabove, a self-centering roller, or more
generally a self-centering rigid stop, is desirable as one of
the numerous disclosed ways in which the side bearing structure
may permit optimization of the side bearing footprint. A
self-centering structure such as a rocker permits accommodation
of a larger radius rolling element in a given rolling pochet
length.
~ s above noted, it is desirable to have available a free
rolling range, or more generally a range of free motion, for the
solid stop bearing element in the longitudinal direction so that
when the wear plate is engaged on the solid stop, relative
movement of the wear plate on the side bearing will not be
restricted by limits on the available range of roller or rocker
movement. If the roller or rocker is free to move throughout an
extended range of relative motion, the restraint characteristic
of the side bearing can be more easily maintained as a uniform
characteristic since rolling engagement of the wear plate with
the roller or rocker element will carry all the overloads beyond
the load magnitude which produces the solid bearing condition
while introducing no significant increment of restraint to
relative pivoting movement between the car body and the truck.
Accordingly, for all overload conditions, the elastomeric
bearing element or elements will be under an esséntially
constant maximum vertical load and the elastomer shear restraint
will be consistent and uniform.
2~47~2~
33
The required range of longitudinal movement for a solid
bearing element can be minimized if the solid bearing element is
positively self-centering. If the solid stop is positively
self-centering, a shorter rolling cavity length will permit a
sufficient range of movement in either longitudinal direction to
accommodate the full range of longitudinal wear plate movement.
Gravitational centering as disclosed in other embodiments
generally will permit more free oscillating motion of the
rolling element when not under load. This results in less
assurance that the rolling cavity limits will permit a
sufficient range of roller motion under overload conditions,
since the roller position when initially engaged by the wear
plate will be less predictable.
~ '19S. 14 and 15 disclose two structures for dealing with
this problem. In Fig. 14, a rocher 194 is disposed within a
cavity 196 of a bearing carrier 198. Opposed recesses 200 on
the longitudinally opposed sides of rocker 194 receive ends of
respective coil springs 202. The opposed ends of the respective
springs 202 are received in recesses 204 which are formed in the
respective longitudinally spaced upstanding end wall portions of
cavity 196. Springs 202 preferably are identical and are
maintained in a state of generally equal compression (which may
include essentially zero compression) with the rocker centered,
so that they exert essentially equal opposing longitudinal
forces which serve to positively center rocker 194
longltudinally within cavity 196. The springs are preferably to
be uncompressed when the rocker is centered, as any difference
in the spring rate or length will result in the rocker being
maintained, whsn not under load, in an off-center position.
20473~4
`_ 34
Fig. 1~ shows one spring bias centering arrangement which exerts
essentially zero spring bias on the rocker at the centered
position.
In Fig. 15 a solid stop structure is shown in which a
rocker 206 is received within a cavity 208 formed in a carrier
210 having longitudinally opposed end walls 21Z which diverge
upwardly and are spaced apart sufficiently to provide a range of
free motion for rocker Z06 therebetween. Spring elements 214
are affixed adjacent the opposed longitudinal sides of rocher
206. Springs 214 are generally of a V-shape having one leg of
the V affixed to a longitudinal side 213 of rocker 206 and the
opposed leg of the V being free to engage a respective cavity
surface 212.
On mo~ement ot the rocker 206 in rocking motion
longitudinally of cavity 208, the free leg of one or the other
of springs 214 engages the respective cavity wall 212 and is
compressed toward the other leg of the same spring to thereby
bias rocker 206 back toward a centered position. Springs 214
thus function in a manner similar to springs Z02 of Fig. 14 to
maintain the rocker 206 in a centered position.
Positive self-centering is not the only benefit of the
spring bias arrangements shown in Figs. 14 and 15. In these
figures, the rocker elements 194 and 206 are shown in bearing
cages with elevated rocker bases. That is, they are shown in
configurations which are described above as being intended for
smaller diameter rollers or rockers. However, when used in an
embodiment without an elevated rocker floor, the positive
self-centering structure can be much more important.
.1 .
20~732~
'~_ 35
Without the elevated rocker floor, a larger diameter
' rocker may be used, and indeed in many circumstances a larger
diameter rocher may be desirable, for example a 4" diameter
rocher. As has been noted, however, a larger diameter solid
bearing element requiring a given minimum longitudinal range of
free movement will require a corresponding longitudinal
clearance within the bearing cage. A larger dlameter roller
thus requires a larger longitudinal clearance. The use of a
rocher, which is essentially a roller with its upper and lower
radiused portions intact and its sides truncated, reduces the
longitudinal clearance requirement and thus helps to optimize
side bearing overall size by minimizing the overall side bearing
length requirement even though the radiused surfaces of the
rocher present a relatively large diameter structure for rolling
engagement with the bearing in the solid condition.
The positive centering structures disclosed in Figs. 14
and 15 serve to permit the further reduction of the longitudinal
clearance required by the rocker since, as noted hereinabove, a
self-centering structure helps to ensure that the rocher element
will be centered when first engaged by the wear plate as the
bearing goes solid. Accordingly, use of a rocker with positive
centering within a space offering à range of free longltudinal
movement permits overall bearing length to be minimized in
general without resorting to a smaller diameter solid stop
bearing element for rolling engagement with the wear plate in
the solid condition. Of course, the Fig. 14 and 15 embodiments
relate to the use of a rocker in lieu of a roller in a much more
,,
20~7324
36
general sense. If a range of longitudinal freedom is provided
for a rocker, the rocker design will be limited by the
requirement that the rocker be stabile , i.e. self-righting when
displaced from its upright position. The disclosed springs may
permit use of a rocker design, for example a rocker of minimal
longitudinal extent, which is not inherently self-righting.
Described hereinabove are.a number of structural advances
in side bearings which permit the overall dimensions of the side
bearing, most notably its longitudinal extent (in the direction
of the car body length), to be minimized. One motive for
achieving such minimal dimensions is seen in the design and
geometry of such railway rolling stock as long intermodal cars
wherein a shorter overall side bearing structure and shorter
bearing footprint are highly desirable due to the more
restrictive bearing space limitations. For example, the
increased distance between the trucks of long intermodal cars
results in a larger maximum angle between the connected cars in
turns. This can result in the adjacent side bearing wear plates
of the pivoted car bodies on the inside of the turn coming into
closer than usual proximity to each other.
All ot the above described asymmetrical bearing structures
wherein a rigid or solid stop is located adjacent to a single
elastomeric bearing element or a compliant bearing assembly can
be of significant benefit for reasons beyond the desirability of
optimizing the bearing footprint or the wear plate surface
dimensions. For example, such an asymmetrical bearing structure
allows freedom in the selection of the maximum load bearing
location with respect to the bolster and the car body.
37 20~732~
,
As has been noted, all bearing loads beyond those required
to bring the bearing to a solid state or condition are carried
by the bearing rocker or roller. Accordingly, by merely turning
the asymmetrical side bearing assembly end-for-end, the location
of the elastomeric bearing element with respect to the location
of the bearing overloads may be changed. In some embodiments of
the invention, this may be accomplished by simply removing the
solid stop, saddle member, and elastomeric column from the
bearing cage and reversing their positions therein. In other
embodiments, the entire side bearing is turned end-for-end. The
invention thus provides a side bearing which is adapted for use
in a variety of configurations to achieve distinctly different
objectives.
More speciflcally, in some rolling stock such as modern
high load capacity cars, the invention permits side bearings to
be placed closer to the truck bolster center line. Side
bearings located as close as possible to the bolster center line
are less able to exert a turning moment on the bolster tending
to rotate it about its longitudinal axis. For those instances ~,
in which it is deemed most desirable to avoid such turning
moments, an asymmetrical side bearing structure of the present
invention may be so mounted that the solid stop is located
longitudinally`closer to the bolster center line and the
elastomeric element is located longitudinally further therefrom.
This orientation will produce the smallest possible turning
moments upon the bolster as all overloads tending to overturn
" the bolster will be acting on the shortest possible moment arm.
~ 38 2 0~7324
There may be other circumstances in which it is more
desirable to locate the solid stop as close as possible to the
car body support structure. For example, in such rolling stock
as long intermodal cars the side bearing wear plates of thé car
bodies may often be supported on outrigger structures which
extend laterally and/or longitudinally from the car body frame
to a position overlying the side bearing carried by the truck
bolster. The required strength of such wear plate support
structureS is determined in part by the distance of the maximum
loads borne by the wear plate from the car body frame.
An incremental strength requirement due to a larger
distance between the car body frame and the furthest point of
maximum wear plate load application will necessitate a more
massive wear plate support structure, including enlarged beam
sections and gussets over those which would be required if the
maximum wear plate loads were borne closer to the car body
frame.
Since the maximum loads borne by the wear plate occur
where the wear plate engages the solid stop of the side bearing, r
an orientation with the side bearing solid stop located closer
to the car body frame and further from the bolster center line
may be desirable in such instances. Of course, in general it is
always desirable to minimize the structural mass of any portion
of a railway car, including the side bearing wear plate support
structure, in order to minimize the car tare weight.
2 4
,
39
The above described side bearing structural features can
be utilized in various combinations to selectively position or
locate the application of overload forces, provide for free
rolling wear plate to bearing engagement throughout the range of
overload forces borne by the bearing after the wear plate goes
solid upon it, maintain uniform elastomeric bearing restraint
(especially shear restraint) throughout the range of overload
forces borne on the side bearing and reduce side bearing
footprint size.
' 10 Accoraing ~o the description hereinabove there is
provided by the instant invention a novel and improved side
bearing assembly for use especially in conjunction with
modern rail car body and truck configurations. Although the
invention has been described with reference to certain
presently preferred embodiments, it will be appreciated that
I have envisioned various alternative and modified
embodiments within the scope of the invention as described.
Among such modifications, I have contemplated a side bearing
generally as above described but with more than two
elastomeric columns spaced longitudinally of a bearing
carrier and with rollers free rolling within limits in
abu-tments members disposed between each pair of adjacent
elastomeric columns. Additionally, a bearing of this
invention may be constructed to the proportions of an
unusually elongated housing member to provide a single
bearing assembly which provides support for both of the
mutually adjacent ends of a pair of car platforms which are
supported on a common truch bolster. The elastomeric
~7324
columns may be configured in a variety of geometric shapes
and from a variety of elastomeric materials according to the
performance requirements of the particular car body and
truck assembly. Certainly such alternative embodiments
would also occur to others versed in thu art, once apprised
of my invention. Accordingly, it is intended that the
invention be construed broadly and limited only by the scope
of the claims appended hereto.
