Railcar truck bolster with immobilized friction shoes

Friction shoes are immobilized within the pockets of a railcar truck bolster by threaded pins that are inserted through apertures in the pocket walls and friction shoes and guided into the inboard pocket wall apertures by a concentric tapered surface within the pockets on the inboard pocket walls.

BACKGROUND OF THE INVENTION 
This invention relates to railcar trucks and more particularly involves 
method and structure for assembling and disassembling friction shoes 
fitted and spring loaded within pockets such as the improved assembly of a 
truck bolster with friction shoes in the bolster pockets, 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 between 
two vertical columns on load springs carried by each side frame. 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 
vertical columns. 
To provide proper damping for the suspension system, friction shoes are 
spring biased in pockets to frictionally retard vertical movement between 
the bolster and the side frame columns. Although it is possible to locate 
such pockets in the side frame columns, it is more common to locate the 
pockets in the bolster. The friction shoes have vertically disposed 
friction faces which contact friction plates secured to the opposite truck 
component. 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 slope surface engages a sloped surface on the 
inside of the pocket. The latter type shoe also has a bottom opening or 
hole through which a control spring extends to the top portion of the 
shoe. The control spring urges the friction shoe against the pocket sloped 
surface and upwardly through the pocket, while the slope also guides the 
shoe outwardly of the pocket against the opposite truck member such as the 
friction plate on the frame vertical column. 
THE PRIOR ART 
When a truck is assembled the shoes, and control springs, are normally 
first placed in 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 into apertures in 
the internal pocket walls through aligned apertures in the shoes. Such a 
technique is taught in U.S. Pat. No. 2,615,403 to Orr et al. Such pins 
are, with difficulty, manually manipulated through the apertures in the 
pocket walls, which apertures ordinarily are provided for both pin 
reception and shoe inspection purposes. The pins must be similarly removed 
after the truck is assembled. Furthermore, it is difficult to precisely 
align the shoe and pocket apertures to enable pin reinsertion if the truck 
must be disassembled for maintenance and the like. 
It has been proposed that the shoes could be compressed and held in place 
within bolster pockets by a full exterior encirclement fastened about the 
outer periphery of the bolster and shoes and which encirclement could be 
easily released. However 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. An acceptable partial encirclement, passing through the shoes and 
bolster pockets, is disclosed in U.S. Pat. No. 4,825,775 to Stein et al. 
However, a shortcoming of both full and partial encirclements is that once 
removed they cannot be reimplaced for truck disassembly. Furthermore, such 
structures are appropriate only for bolster applications. 
Accordingly, a preassembled pocket with pre-compressed friction shoe held 
in place with immobilizing means that is easily removed and reimplaced 
would be of benefit to the railroad industry. Such pre-assembly could be 
most expeditiously undertaken at a truck component manufacturing facility 
rather than at a truck or railcar assembly point, yet the immobilizing 
means could be both removed or reimplaced at any truck assembly or 
maintenance facility. 
SUMMARY OF THE INVENTION 
Accordingly, it is a primary object of the present invention to provide a 
method for assembling a railcar truck friction shoe held compressed within 
a pocket by immobilizing means that is easily both removed and replaced. 
It is another object of the present invention to provide a railcar truck 
friction shoe which is held compressed within a pocket by immobilizing 
means that is easily both removed and replaced. 
It is still another object of the present invention to provide a method for 
assembling a railcar truck bolster with friction shoes held compressed 
within bolster pockets by immobilizing means that are easily implaced, 
removed and replaced after being removed from the shoes and pockets. 
It is yet another object of the present invention to provide a railcar 
truck bolster preassembled with friction shoes which are held compressed 
within the bolster pockets by immobilizing means that are easily implaced, 
removed and replaced after being removed from the shoes and pockets. 
A further object of the present invention is to provide an improved railcar 
truck pocket structure having guide means within the pocket to direct an 
immobilizing means into a receiving aperture in an inboard pocket wall. 
Still another object of the present invention is to provide an improved 
railcar friction shoe having notches to cooperate with pocket wall guide 
means for directing an immobilizing means into a receiving aperture in an 
inboard pocket wall. 
In brief the present invention comprises the application of an immobilizing 
means through friction shoe and pocket wall apertures wherein the pocket 
wall aperture that last receives the immobilizing means includes a guide 
means adjacent thereto to direct the immobilizing means to that aperture. 
Preferably the immobilizing means is a threaded and pointed shaft; and the 
friction shoe includes notches cooperating with the pocket wall guide 
means.

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 no shown). A transverse bolster generally 20 having open ends 
22 extends between two side frames 10 whereupon the bolster is 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. Extending inward from each side 
wall near each bolster end 22 there are pockets generally 36 formed by 
spaced inboard and outboard walls 40, 42 (respecting the bolster ends 22) 
which extend to the bottom wall 30 from opposite openings in the side 
walls, 32, 34 and adjacent areas of the too wall 28. Each pocket 36 also 
includes inner wall 44 interconnecting the inboard and outboard walls 40, 
42. The pockets 36 and particularly the walls 40, 42 are contoured to 
slidingly receive a particular shaped friction shoe such as shoe 66 
hereinafter described in detail. Vertical gibs 50, 52 are formed in each 
of the side walls 32, 34 adjacent 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 moveable vertically between closely 
spaced friction plates 56 that are disposed on vertical columns 60, 62 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. The friction shoes generally 66 are reciprocally 
mounted and compressed on control springs 70 within the pockets 36 so as 
to be urged outwardly of the pockets and against the friction plates 56. 
Each friction shoe 66, as shown in FIG. 6, comprises a hollow body to 
receive the spring 70 having top portion 74, side portions 76, a bottom 
foot 78, a vertical friction face 80, and a web B2 opposite the friction 
face. The shoe 66 is placed in its respective pocket with the friction 
face 80 disposed outwardly to engage a friction plate 56 on the side frame 
10. As may be seen in FIG. 5, the respective control spring 70 extends 
upwardly through a hole in the foot 78 of a shoe, from a spring seat 84 on 
the bolster bottom wall 30 within pockets 36 and against the underside of 
the shoe too portion so as to urge the shoe out of the pocket. 
The particular friction shoe 66 illustrated in FIG. 5 also has side wings 
86 with sloped surfaces 88 extending essentially between the levels of the 
top portion 74 and foot 78 and declining away from the friction face 80, 
and there are slots 90 in each side portion 76 that are generally parallel 
to the sloped surfaces 88. The sloped surfaces 88 of shoe 66 are 
positioned inwardly of the pockets 36 so as to engage mating inboard and 
outboard bolster slope walls 92, 94 formed in the respective pocket 
internal walls 40, 42 so that the shoes are directed against the friction 
plates 56. 
As may be seen in FIGS. 3, 4 and 5 apertures 100, 102 are located in the 
respective inboard and outboard walls 40, 42 of pocket 36 so as to be 
aligned with vertical portions of slots 90 in the shoe 66 when the latter 
is compressed against its control spring 70. According to the prior art, 
as shown in FIG. 1, the shoes could be temporarily held in the compressed 
attitude by inserting smooth pins through the apertures 100, 102 and shoe 
slots 90. 
The present invention provides a method and structure for immobilizing the 
friction shoes 66 within bolster pockets 36 and holding the shoes 
compressed and immobilized therein for an indefinite period. The method 
and structure hereafter described have an advantage of being easily 
repeated and replaced on a given shoe and bolster pocket and therefore 
have application in both preassembling a bolster with friction shoes 
inserted therein before being mounted in truck side frames and also for 
reimmobilizing the shoes within bolster pockets when it is necessary to 
perform maintenance thereon. 
This invention is accomplished by providing the aforementioned apertures 
100, 102 in the form of circular holes in the respective outboard and 
inboard pocket walls 40, 42 and forming a guiding means such as an inward 
taper or conical countersink 104 on the interior pocket surface of the 
inboard wall 40 concentric to the aperture 100. It is to be understood 
that the taper 104 assists in guiding and directing a pin or the like into 
the aperture 100. Preferably the taper 104 extends inwardly of the pocket 
on a projecting semiencircling boss 120, as seen in FIGS. 4 and 5, located 
toward a bolster side wall 32, 34 outward of the aperture 100 which is the 
direction that a shoe 66 will be urged by spring 70 and sloped surfaces 
92, 94. 
Thus by first compressing a friction shoe 66 against its control spring 70 
into a pocket 36, and thereby generally aligning the slots 90 in the shoe 
66 with pocket apertures 100, 102, the shoe may be immobilized against 
outward movement by inserting therethrough an immobilizing means, such as 
a pin generally 124. The guiding means countersink 104 assists in 
directing the pin 124 into aperture 100 should the pin be angled 
vertically or should shoe slots 90 be slightly out of alignment and cause 
the pin 124 to be angled outwardly. The guiding means is further enhanced 
if it includes the aforementioned semi-encircling boss 120. 
Preferably the pin 124 is pointed at an insertable end 126 to further 
facilitate aiming into the aperture 100. Additionally the pin 124 should 
be provided with an enlarged head 128 at the end opposite point 126 to 
facilitate manipulation of the pin and also the extraction thereof. 
In the most preferred embodiment of the immobilizing means the pin 124 has 
a helical surface, such as a coarse thread 136, along its length and the 
enlarged head 128 is configured, as by the hexagonal head illustrated, to 
accept a wrench or other tool by which the pin 124 may be twisted. 
It will thus be understood that by pushing pin 124 through the aperture 102 
in the outboard pocket wall 42 and through slots 90 in shoe 66 and against 
the tapered countersink surface 104, the pin will lever the shoe slots 90 
into alignment with both apertures 100, 102. Further pushing will result 
in the pin 124 extending through aperture 100. By also twisting the pin 
124 in one direction (usually clockwise) the action of the helical surface 
of thread 136 against a rim of aperture 100 will cause the pin to be drawn 
inward. Furthermore the helical surface will tend to prevent withdrawal of 
the pin 124 from aperture 100 unless it is twisted in a reverse direction. 
The latter feature is further enhanced by the tapered surface 104 of 
aperture 100 so as to present a smaller diameter hole and pronounced sharp 
angled rim on the inboard side of inboard pocket wall 40. 
The threaded pin 124 may also be readily extracted by reverse twisting in 
which case the action of the thread 136 against edges of the shoe slots 90 
and the aperture 102 will cause the pin to move in an outboard direction. 
It should be noted in FIG. 7 that a preferred friction shoe 66' includes 
notches 114 in web 82' to pass over the boss 120. Since a shoe 66' may be 
placed in either the left or right side pocket of a bolster but the boss 
120 is always to be located on the inboard pocket wall 40, it is necessary 
to make symmetrical inwardly extending notches 114 from both sides of the 
shoe. 
As shown in FIGS. 1, 2 and 4, it is usual that the ends 22 of a bolster 20 
are open. This permits access for the aforedescribed inserting and 
extracting of pins 124. It is also to be noted in FIGS. 2, 3 and 4 that a 
warning and instruction strap 150 is preferably impaled by pins 124 
outboard of the pockets 36. There are a number of advantages to the 
placement of strap 150. Foremost it is more visible than the heads 128 of 
the pins 124 and serves to warn that the pins must be removed after the 
bolster 20 is placed in side frames 10. To further enhance this function 
the strap 150 may be vibrantly colored and have instructional information 
displayed thereon. Secondly, the strap 150 may be shaped or located to 
stand away from apertures 102 and hold the pin heads 128 spaced outboard 
of the outboard pocket walls 42 whereby they be easily accessible to an 
appropriate tool such as a socket wrench. This may be important where the 
pocket wall structure, as shown, includes angles closely adjacent the 
apertures 102 which would otherwise interfere with placement of the tool 
on the pin head 128. Further where the strap 150 is shaped or located to 
hold the pin head 128 outward of the aperture 102 the pin 124 must itself 
by sufficiently long to extend through the inboard aperture 100 and the 
strap will begin to deform only after the pin thread 136 engages the rim 
of aperture 100 thereby indicating the shoe 66 is safely immobilized. 
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 int 
he following claims.