Railcar truck bolster with preassembled friction shoes

Friction shoes are preassembled in each end of a railcar truck bolster by providing openings in the bolster and in the shoes and passing a restraining member through the openings at each bolster end and tensioning and securing the restraining members so as to hold the shoes within respective pockets in the bolster. The shoes and pockets are further provided with cooperating anti-ejection features to prevent ejection of shoes after installation.

BACKGROUND OF THE INVENTION 
This invention relates to railcar trucks and more particularly involves a 
method for preassembling a bolster with friction shoes fitted therein, the 
improved assembly of a bolster with friction shoes and improved bolster 
and shoe components therefore. 
A typical railcar truck comprises wheelsets mounted on two axles which 
support side frames at each side of the railcar and a transverse bolster 
extending between the side frames with the ends thereof supported on load 
springs carried by each side frame between two vertical friction plates. 
Usually a truck is located under each end of a railcar and the car itself 
is pivotally supported upon a centerplate centrally positioned on each 
bolster. Thus the weight of the railcar will cause the ends of the 
bolsters to move vertically on the load springs while confined between the 
friction plates. 
To provide proper damping for the suspension system, friction shoes are 
located in pockets to each side of the bolster adjacent the side frame 
friction plates. The friction shoes have vertically disposed friction 
faces which contact the friction plate. In certain types of such friction 
shoes there is a shoe slope surface, generally opposite the friction face, 
which declines from a top portion of the friction shoe to a bottom portion 
thereof and away from the friction face and which engages a bolster slope 
surface on the inside of the pocket. The latter type shoe also has a 
bottom opening or hole through which a control spring extends from the 
bolster to the top portion of the shoe. The control spring urges the 
friction shoe against the bolster slope and upwardly through the pocket, 
while the slope also guides the shoe outwardly against the vertical 
friction plate. 
THE PRIOR ART 
When a truck is assembled the shoes, and control springs, are normally 
first placed in the bolster pockets at the assembly site and thereafter 
the bolster ends are inserted through each respective side frame. The load 
springs are then positioned in each side frame and the bolster ends 
lowered thereon. Normally it is necessary to temporarily compress and 
secure each of the shoes fully within the respective bolster pockets so 
that the bolster ends may be inserted between the side frame friction 
plates. In the past this has been done by inserting pins through holes in 
the internal pocket walls into corresponding holes in the shoes. Such pins 
are, with difficulty, manually manipulated through inspection openings in 
the bolster walls; and must be similarly removed after the truck is 
assembled. 
It has been proposed that the shoes could be compressed and held in place 
by a full exterior encirclement fastened about the outer periphery of the 
bolster and shoes and which could be easily released. However this is not 
practical as such an encirclement interferes with proper bolster side wall 
placement between the side frame vertical friction plates. Moreover such a 
full exterior encirclement, when released, is immediately gripped between 
the friction shoe friction face and the side frame friction plates where 
it will interfere with proper movement of the parts. Accordingly, an 
easily releaseable preassembled bolster with pre-compressed friction shoes 
without sideward interference would be of significant benefit to the 
railroad industry. Moreover such pre-assembly could be most expeditiously 
undertaken at a bolster manufacturing facility rather than at a truck or 
railcar assembly point. 
SUMMARY OF THE INVENTION 
Accordingly, it is a primary object of the present invention to provide a 
method for pre-assembling a railcar truck bolster with friction shoes 
releasably held compressed within bolster pockets by means of restraining 
members that do not extend to the sides of the bolster, but which may be 
easily released from outside the bolster. 
It is another object of the present invention to provide a railroad truck 
bolster preassembled with friction shoes which are releasably held 
compressed within the bolster pockets by means of restraining members that 
do not extend to the sides of the bolster but which may be easily released 
from outside the bolster. 
A further object of the present invention is to provide an improved railcar 
truck bolster having means within the bolster pockets to receive a 
restraining member that does not extend outside the bolster side walls. 
Still another object of the present invention is to provide an improved 
railcar bolster friction shoe having means to receive a restraining member 
by which it may be releasably held compressed within a bolster pocket. 
Yet another object of the present invention is to provide improved railcar 
truck bolster and friction shoe structures which inhibit ejection of the 
shoe from a bolster pocket. 
In brief the present invention comprises the application at each end of a 
bolster of a restraining member, such as a narrow strap, which extends 
through openings in the walls defining two opposite pockets at one end of 
a bolster upwardly through each friction shoe placed therein and through 
openings in the top portions of those friction shoes. Preferably the 
restraining member is a partial encirclement that extends across the 
exterior surface of the bolster top wall between two opposite shoes.

DETAILED DESCRIPTION OF THE INVENTION 
Existing railcar structures employ trucks comprising side frames generally 
10 which are supported above bearings (not shown) resting on axles and 
wheels (also not shown). A transverse bolster generally 20 extends between 
two side frames 10 with each bolster end portion 22 supported on load 
springs 24 seated in the side frames 10. The bolster is usually an 
essentially hollow member of cast steel having a top wall 28, bottom wall 
30 and two opposite side walls 32, 34. At each bolster end 22 there are 
two pockets generally 36, 38 formed by internal walls 40, 42, 
respectively, which extend to the bottom wall 30 from opposite openings in 
the side walls, 32, 34 and adjacent areas of the top wall 28. Usually 
raised lands 46, 48 partially surround the respective pocket 36, 38 
openings in the bolster top wall 28; and vertical gibs 50, 52 are formed 
in each of the side walls 32, 34 onward of the pocket openings therein. 
When assembled with the side frames 10, the bolster ends 22 are urged 
upward by the load springs 24 and are movable vertically between closely 
spaced friction plates 56, 58 that are vertically disposed in the side 
frames, with the gibs 50, 52 located at the outward and inward edges of 
the friction plates so as to prevent separation of the bolster 20 from the 
side frame 10. Friction shoes generally 66, 68 are reciprocally mounted on 
control springs 70, 72, respectively, within the respective pockets 36, 38 
so as to be urged against the friction plates 56, 58. 
Each friction shoe 66, 68 comprises a hollow body having top portion 74, 
side portions 76, a bottom foot 78 and a vertical friction face 80, and is 
placed in its respective pocket with the friction face 80 disposed to 
engage a friction plate 56 or 58. As may be seen in FIG. 3, the respective 
control spring 70 or 72 extends upwardly through a hole in the foot 78 of 
a shoe, from a spring seat 86, 88 on the bolster bottom wall 30 within 
pockets 36, 38, and against the underside of the shoe top portion so as to 
urge the shoe out of the pocket. 
Each shoe 66, 68 also has sloped surfaces 90 extending essentially between 
the levels of the top portion 74 and foot 78 and declining away from the 
friction face 80. The sloped surfaces 90 of shoes 66, 68 are positioned 
inwardly of the pockets 36, 38 so as to engage mating bolster slopes 92, 
94 formed in the respective pocket internal walls 40, 42 so that the shoes 
are directed against the friction plates 56, 58. 
According to the present invention the friction shoes 66, 68 may be 
preassembled and held fully compressed against control springs 70, 72 
within the pockets 36, 38 of a bolster generally 20 by providing openings 
or slots 98 in one of the walls defining each pocket (either the bolster 
bottom wall 30 or an internal pocket wall 40, 42) and an opening or slot 
100 in each shoe top portion 74, spaced away from the friction face, 
passing a restraining member 102 through the slots 98, 100, moving each 
shoe 66, 68 inwardly within the respective pocket to compress each control 
spring, tensioning the restraining member to hold the shoe compressed in 
the pocket and then securing or anchoring the restraining members while 
tensioned. 
One way in which the foregoing method may be accomplished is to pass 
separate strands through each shoe and its respective pocket and anchor 
each end thereof (such as by knotting or applying fasteners) at the 
exterior of the respective openings in the shoe and pocket wall. 
A preferred method for pre-assembling the shoes and bolster in the manner 
shown in the drawings is to pass a band 106 first through slots 98 in the 
pocket walls (either internal wall or bolster bottom) of two opposite 
pockets 36, 38 at one bolster end 22 and pull the band 106 so that equal 
lengths extend out of each pocket. Each such end is then threaded through 
the spring hole in the bottom foot 78 and the slot 100 in the top portion 
74 of each respective shoe 66, 68 and each control spring 70, 72 is 
inserted in the respective shoe. Both shoes 66, 68 are then compressed 
within the respective pockets 36, 38 and the ends of band 106 are drawn up 
tightly toward one another and tensioned across the top wall 28 of the 
bolster 20 where the band ends are secured together, under tension, so as 
to hold the shoes compressed within the pockets. In the preferred 
embodiment the band 106 is made of steel and the ends are secured together 
by a metal clamp or clip 108 which is crimped thereon. The ends could also 
be riveted or welded together and there are other materials, such as 
plastics that may be suitable for the band. 
It will be seen in the figures that the preferred embodiment of 
preassembled parts comprise a bolster generally 20 with friction shoes 66, 
68 held compressed within pockets 36, 38 at each end 22 thereof by bands 
106 which extend through the bolster 20 and shoes and are secured by 
clamps 108 exterior of the bolster top wall 28. Notably the bands 106 do 
not extend around the bolster side walls 32, 34 nor across the shoe 
friction faces 80. Thus the bands 106 are deemed to be partial 
encirclements of the bolster ends 22 and shoes 66, 68, because the bands 
106 are closed upon themselves and extend around parts of each shoe and 
bolster end and outside of at least the top or bottom wall of the bolster 
end. 
When preassembled in the aforedescribed manner, the bolster 20 may be 
shipped to the truck assembly site and there inserted in the lower areas 
of each side frame 10 and then lifted into position between the side frame 
friction plates 56, 58. Usually the bolster 20 will be held in this 
position, slightly lowered from the top travel limit, whereby the 
restraining members may be severed in the upwardly exposed area above the 
bolster top wall so as to free the shoes 66, 68 to move into contact with 
the friction plates 56, 58. In some instances the severed restraining 
members may simply be left in place. With the preferred embodiment it is 
advantageous to engage the clamp 108 with bifurcated fork and, after the 
band 106 is severed, the band is removed by winding it onto the fork. 
Thereafter it is usual to insert the load springs beneath the bolster ends 
22. 
It may also be observed in the drawings that there are two alternatives to 
the aforedescribed preferred embodiment. According to one alternative the 
slots 98 in the bolster wall are located in the bottom wall 30 adjacent 
each control spring seat whence the band 106 will extend outward both 
above and below the bolster 20. In a second alternative the slots 98a are 
located in the internal pocket walls 40, 42, at the base of the innermost 
portions thereof also near the control spring seats, in which case the 
band 106 will extend outward of the bolster 20 only at the top. 
A further improvement feature illustrated in the drawings is an 
anti-ejection means to prevent loss of one or both shoes 66, 68 should the 
restraining member (or band 106) be accidentally broken during shipment of 
a preassembled bolster. The anti-ejection means comprises inclined grooves 
116 in the side portions 76 of each shoe 66, 68, which grooves 116 extend 
parallel with the shoe slope 90 and extend partially into the shoe portion 
opposite the friction face, and small lugs 118, 120 projecting inwardly 
from the bolster top wall 28 at each side of a pocket near a bolster side 
wall (e.g. pocket 36 near side wall 32 and pocket 38 near side wall 34). 
When the respective shoe 66, 68 is inserted into its pocket 36, 38 the 
inclined grooves 116 are first fitted over the lugs 118, 120. Each groove 
then tracks on an interfitting lug; and the shoes cannot be removed from 
the bolster sideways except when lifted to the very top of the pocket. 
Thus each shoe will normally be retained at least partially in its pocket 
and will not be ejected therefrom after being inserted. 
The foregoing detailed description has been given for clearness of 
understanding and to provide a complete description of a preferred 
embodiment of the invention. Various modifications may be made without 
departing from the spirit and scope of the invention which is defined in 
the following claims.