Torsion bar railway truck

A railway truck has frames on each side divided into separate components or lever arms extending from the axles. Opposed arms are secured together by a pair of parallel torque tubes. A bolster rides on the tubes and maintains the tubes in parallel and provides frictional damping. The torsion tubes each carry a pair of torsion bars secured at the inner end to the torque tube and to the outer end to the bolster. Unequal loads on opposite wheels are carried equally by the torsion tubes.

BACKGROUND OF THE INVENTION 
This invention relates to railway rolling stock and more particularly to 
railway trucks, which ride on rails and provide support for car bodies. 
Many of the design features of railway trucks have remained the same over 
the past century, with improvements being made primarily in refinement of 
individual components and scaling up of the components for carrying higher 
capacities. A conventional truck comprises a pair of spaced parallel 
unitary side frames which are supported near their ends on wheel and axle 
assemblies. A transverse bolster centrally connects the side frames, and 
the ends of the bolster are supported on helical springs carried in 
opposed side frame windows. The bolster resiliently supports the car body. 
Mechanical snubbers are employed to dampen vertical movements of the 
bolster, and shoes are carried by the bolster and frictionally engage 
vertical columns on the side frame. 
While the prior art is crowded with many suggestions to improve the ride 
and performance of so-called three piece trucks of the foregoing nature, 
many problems have remained unresolved, presumably due to characteristics 
inherent in the design. The side frames, which form rigid connections 
between the front and rear wheels on each side of the truck, are heavy 
castings. This necessarily results in a high unsprung weight between the 
wheels and bolster, contributing to poor riding qualities. The two trucks 
beneath the car may contribute up to forty percent of the tare weight of 
the total structure. 
A second problem with existing truck designs is unlevel riding qualities 
under varying speeds, loads and track conditions. One example is a 
phenomena of rock and roll, in which the car body and trucks may rock from 
side to side to a dangerous degree. 
Another problem is the inability of present designs to maintain a square 
condition because of the H relation between the side frames and the 
bolster. The bolster has portions in slidable engagement with columns of 
the side frame, and these parts tend to wear over a period of time. The 
design contributes to the problem known as hunting, in which the wheels on 
one side of the truck may precede the wheels on the other side and cause 
an erratic ride. The problem may become intensified as the relevant parts 
become worn. 
Finally, conventional railway trucks contain numerous cooperating parts 
which must be carefully engineered in order to perform in a satisfactory 
manner, all contributing to cost. Notwithstanding all these problems and 
more, there has been a reluctance to deviate or make fundamental 
departures from the current basic design. 
SUMMARY OF THE INVENTION 
An object of this invention is to provide a railway truck having greatly 
improved and level ride characteristics, irrespective of loading, speed 
and track conditions. 
Another object is to provide a truck having a substantially lower unsprung 
weight and yet same capacity of conventional designs. 
A further object is the provision of a railway truck which is inherently 
square in design and contains features which positively maintain a square 
relation between the wheels in a reliable manner. 
Another object is to provide the wheels of a truck with independent 
suspension wherein the forces on opposed wheels is summed by a common 
connecting member. 
A still further object of this invention is to provide the sprung portions 
of such a truck with effective damping without the use of separate 
snubbers and associated parts. 
Another object is to provide a railway truck of simplified design, having 
fewer working parts as well as fewer parts which are subjected to wear, 
thereby reducing manufacturing and maintenance costs. 
The foregoing objects are generally accomplished by eliminating the one 
piece side frame on each side of the truck in favor of separate 
independent frames in the form of lever arms having one end journaled on 
the axle and the other ends extending toward each other on each side of 
the truck. Opposed lever arms on opposite sides of the truck are connected 
by transverse torsion tubes extending across the truck in parallel on 
either side of the transverse center line of the truck. A bolster rides on 
and frictionally engages the tubes near the ends thereof in order to hold 
the tubes in a parallel relation and hence the components of the truck in 
a square relation. At the same time, frictional engagement between the 
bolster and tubes, which occurs during vertical motion of the bolster and 
rotary motion of the tubes, provides effective damping, with increased 
friction at heavier loads. Each torsion tube carries a pair of torsion 
bars. The inner ends of the torsion bars are secured at the center of the 
tubes, and the outer ends are secured to the bolster ends. The torsion 
bars thereby serve as the spring component of the truck. 
As a result of the foregoing configuration unequal forces on opposed wheels 
are divided equally between the two torsion bars, acting under the 
influence of the torsion tube and associated lever arm frame. The result 
is a truck having a level ride. 
Since the lever arm frames are connected directly to the torsion tubes and 
bars, the truck has a low unsprung weight. The bolster holds the two ends 
of the truck in a square relation, thereby minimizing hunting problems. 
Unlike conventional designs, the side frame components are not subjected 
to frictional wear, and any wear between the bolster and torsion tubes 
does not cause loss of ride qualities.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As shown in FIGS. 1-3, the truck includes conventional wheel and axle 
assemblies, in which opposed wheels 10 are secured to an axle 12 and 
journaled to an associated frame member by means of conventional rotary 
bearings 14 between the end of the axle and frame member. Although only 
one side of the truck is shown, it will be understood that the other side 
is identical to the illustrated portion. Likewise, both ends of the truck 
connected by the bolster are identical. 
Each end of the truck comprises pairs of opposed rigid frame members 16 and 
18 having conventional pedestal openings 20 having the usual bearing 
adaptor (not shown) for engagement with the bearings 14. The frame members 
16 and 18, having a length less than one half the length of the truck, 
terminate in free ends 22 and 24, and said ends, on opposite sides of the 
truck, are connected by a transverse torque tube 26 secured at each end to 
a respective frame member and having portions 28 thereof extending 
outwardly beyond the frame members. The other end of the truck is provided 
with an identical assembly, with the torque tubes being arranged in 
parallel on a horizontal plane on either side of the transverse central 
axis of the truck. 
A unitary bolster 30 is provided with an upper horizontal wall 32 and a 
depending central vertical web 34 of T-shape fabricated construction, as 
shown. In the alternative, the bolster 30 may be of I-beam construction, 
with a bottom horizontal wall 36 as shown in FIGS. 1 and 2 secured to the 
bottom of web 34. The bolster 30 is of a simpler design than conventional 
designs, which are of cast construction with a box section to provide 
adequate structural support. The bolster has a female center plate 37 for 
carrying the male center plate of the car body (not shown). 
A pair of downwardly depending flanges 38 and 40 are provided near each end 
of the bolster 30. Respective flanges 38 and 40 have downwardly facing 
concave or semi-circular bearing surfaces or walls 42 and 44 which embrace 
and rest on the torque tube 26 and its extension 28 on either side of the 
frame 16 and 18. The walls 42 and 44, as well as corresponding surfaces on 
the tube, may be designed such that they may be replaced in the event of 
the excessive wear, such as use of the wear liners as shown. 
It may be seen that the bolster 30 positively holds the torque tubes 26 in 
a parallel relationship. The friction between the bolster and torque tubes 
increases with increasing loads on the bolster to provide progressive 
damping. 
As best shown also in connection with FIGS. 4 and 6, a pair of torsion bars 
or shafts 46 and 48 are received in each torque tube 26. As shown in FIG. 
4, the center of the tube is provided with an insert 50 secured in the 
tube and having a pair of hexagonal sockets 56 adjacent to the slug on 
either side thereof. An enlarged nut or slug 52 and 54 is secured on the 
inner end of each torsion bar 46 and 48 and is slidably received in the 
sockets 56. The outer ends of torsion bars 46 and 48 terminate in enlarged 
multifaceted or hexagonal ends 58, which are secured to the ends of the 
bolster, as described below. 
As shown in FIGS. 1-3, a third outermost wall 60 depends downwardly from 
the top wall 32 of the bolster 30 and is provided with a central opening 
61 and a number of openings 62 to receive bolts 64. As shown in FIGS. 1, 3 
and 5 plates 66 having hexagonal openings 68 and bolt holes 70 are 
disposed on either side of the outer bolster web or flange 60. As shown in 
FIG. 1, the innermost plate 66 has threaded openings to engage with the 
threaded ends of the bolts. 
Upon insertion of the torsion bars 46 and 48, the outer faceted end is 
secured to the bolster wall 60 by means of the plates 66 and bolts 64 
received through an outer cap 72. Thus, the outer ends of the torsion bars 
46 and 48 are anchored relative to rotary motion of the torque tube 26. 
The torque tubes 26 have a torsional stiffness in the order of 10 to 20 
times the stiffness of the torsion bars 46 and 48, so the torsion bars 
provide the primary springing for the truck and are enclosed and are 
protected by the torque tube. The torque tubes also prevent lateral 
displacement between the bolster and the side frame members. 
In actual use, the bolster may be designed for up to 4.5 inch or greater 
vertical travel relative to the axles. Under empty car conditions, the 
downward travel would be less than one quarter available travel. Under 
loaded conditions, the travel would be in the order of three quarters of 
total available travel. 
It may be seen that as the bolster 30 moves downwardly due to loading, the 
torque tube 26 rotates. For example, the forward tube will rotate in a 
counterclockwise direction and the rear tube will rotate in a clockwise 
direction. This motion applies torque on the torsion bars 46 and 48, which 
progressively and resiliently resist such movement. 
From a different perspective, assume that there are unequal loadings on the 
front wheels, for example, due to unequal weight distribution in the car 
body or track irregularities. This will result in unequal forces at the 
wheels and unequal torques at the ends of the torque tube 26. 
FIG. 4 includes an illustration of the torques on the various components. 
Assuming that the torques and TBR on the outer ends of the tube are 
unequal, these are summed at the center of the tube as torque TTC, with a 
counter torque TBC on the inner ends of the torsion bars. The counter 
torques TBC is equal to the sum of the torques an TBR on the torsion 
bars, and these torques are equal. Thus, unequal forces at the wheels 
produce a single torque at the center of the torque tube which is equally 
resiliently divided by the torsion bars. Thus, forces on the front wheels 
and rear wheels are equalized to provide a smooth and level ride. The 
front and rear wheel sets are independent but have equal spring loading 
and equal net damping. The two torsion bars in effect provide a single 
spring or resilient means resisting rotation or torque at the center of 
the torque tubes. 
It may seem that the only wear in the truck is between the concave surfaces 
on the bolster and the torsion tubes. Wear on these parts, however, will 
have no adverse effect on the performance of the truck and will not allow 
the truck to go out of square. The torque tubes provide a solid tie across 
the truck and, together with the bolster, maintain the truck in a square 
relation.