US3433177A - Resilient stabilizing railway truck assembly - Google Patents

Description

March 18, 1969 A. R. CRIPE 3,433,177

I RESILIENT STABILIZING RAILWAY TRUCK ASSEMBLY Filed March 1, 1966 Sheet of e INVENTOR I AMA/v A? C/Q/PE BY Z W/ Q. X...

ATTORNEY March 18, 1969 A. R. CRIPE 3,433,177

RESILIENT STABILIZING RAILWAY TRUCK ASSEMBLY Filed March 1, 1966Sheet 2 of a March 18, 1969 A. R. CRIPE 3,433,177

RESILIENT STABILIZING RAILWAY TRUCK ASSEMBLY Filed March 1, 1966 sheet of e March 18, 1969 A. R. CRIFE Filed March 1, 1966 Sheet 4 l V- L- March 18, 1969 A. R. CRIPE 3,433,! 77

RESILIENT STABILIZING RAILWAY TRUCK ASSEMBLY Filed March 1, 1966Sheet 5 of 6 March 18, 1969 R, CRIPE 53,433,177

RESILIENT STABILIZING RAILWAY TRUCK ASSEMBLY Filed March 1, 1966Sheet 6 of s fie. 10

iii? -Il1 fcJZ United States Patent 3,433,177 RESILIENT STABILIZING RAILWAY TRUCK ASSEMBLY Alan R. Cripe, Richmond, Va., assignor to United Aircraft Corporation, East Hartford, Conn, a corporation of Delaware Filed Mar. 1, 1966, Ser. No. 530,960

11.8. Cl. 105199 12 Claims Int. Cl.B61f 5/26, 3/04, 1/06 ABSTRACT OF THE DISCLOSURE A railway truck assembly is described which incorporates independently-oscillatory side frames which directly support a bolster on which in turn a vehicle body is resiliently mounted through torsilastic mountings which allow controlled rolling of the body. A gimbal member held captive between the side frames serve as the pivot point for the bolster and the side. frames and means, particularly pillow blocks, are provided between the confronting surfaces of the side frames and the bolster for accommodating a relative rocking motion therebetween.

This invention relates to railway vehicle truck assemblies for lightweight high performance articulated trains.

The operating parameters specified for the more advanced lightweight passenger trains contemplate normal operating speeds nearly double those of conventional trains. At these higher speeds even minor track irregularities and discontinuities are magnified into major sources of passenger discomfort and equipment stress. To minimize the adverse effects of high speed travel, generous use is made of flexible and resilient mountings and connections to eliminate, where possible, all direct transmission routes for noise and vibration between their source and the vehicle interior to isolate the passenger therefrom. Such practices inherently allow considerable freedom of movement at the various connections within limits established by the degree of resilience provided in the mountings.

Further, in most truck assemblies many of the various components comprising the assembly are designed to allow relative movement therebetween independent of the other components. In some constructions, for example, the side frames, which are the basic load-carrying members supported on the rotating axles, are permitted to oscillate in a vertical plane independently of each other and independently of the vehicle. Accordingly, each side frame is allowed to assume its own angle of attack in a vertical plane as a function of the angle assumed by the rail over which it rides. As a result, the effects of a roadbed unevenness at one rail are not transmitted to the entire assembly.

Still further, truck constructions necessarily allow a pivotal movement of a portion of the truck in a horizontal plane around a given vertical axis. The necessity for such pivotal movement of the truck with respect to the vehicle body is evident since the truck always turns into or out of a curve in the track at a different rate than that of the vehicle itself.

At very high train speeds, however, truck stability becomes a major problem. While the hereinbefore discussed freedom of movement is advantageously incorporated into a truck assembly, it must nevertheless be rigidly controlled so that the geometry of movement is confined in fixed planes.

One of the principal objects of my invention, therefore, is to provide a lightweight railway truck assembly which is characterized by a high degree of freedom of movement between its various components but which 3,433,177 Patented Mar. 18, 1969 confines the geometry of movement to predetermined planes to provide stability of operation at high track speeds.

A current design of a lightweight passenger train incorporates an advanced suspension system wherein the cars are caused to bank on curves in a manner similar to aircraft flight. These trains, for this purpose, utilize an improved version of the radially-guided, single-axle, pendulum suspension system shown and described in my prior Patent 2,954,746. In this system a single axle mounted between the cars is used to provide support for the ends of both of the abutting car bodies and the axle is steered to maintain it perpendicular to the track at all times. Accordingly, the wheels always assume a zero angle of attack with respect to the rail.

A powered dome car is provided at each end of this truly bidirectional train, each dome car carrying at least part of the propulsion and auxiliary power for the train, and being adapted additionally to transport passengers therein. Dual-axle powered trucks of an advanced design are used at the free end of each ofthese dome cars as support therefor, the articulated end being provided with the single axle, pendulum-type support as hereinbefore discussed. Because of the pendulum support at the articulated end of the car, this end is adapted to bank on curves. This tendency would be resisted if a conventional truck assembly were incorporated in the train design since the conventional truck assembly is specifically designed to oppose any rolling movement of the car body. It is, therefore, necessary to incorporate in the truck assembly means for encouraging a controlled roll of the car body about a longitudinal axis whereby the desired banking on curves may be achieved and to make the truck system compatible with the suspension system installed intermediate each of the cars. This is particularly important in this train since passengers will be carried in the powered or locomotive units.

Another object of my invention, therefore, is to provide a railway truck assembly which permits controlled rolling of the car in which it is installed whereby the car is caused to bank on curves.

The weight of the car body is taken through air springs and their supporting structural members to a bolster which is in turn vertically supported on the respective side frames. A substantial contact area is provided between the bolster and its confronting side frame and usually a sliding surface is provided therebetween since the bolster must slide on the side frame as the train enters a curve and a portion of the truck assembly rotates beneath it. However, since the side frames may experience limited rotation in a vertical plane beneath the bolster as the wheel negotiate irregularities in the track, their confronting surfaces are caused to assume an angle of attack with respect to one another. In'other constructions this is compensated for to a limited extent through the use of a resilient slide support positioned in the side frame beneath an appropriate bearing surface. In these constructions, however, a greater wearing force is transmitted to one end of the bearing surface than the other. Further, because this force is carried over a smaller bearing area, a greater frictional factor is created which resists the sliding movement of the bolster at one side of the assembly. At very high speeds this fore-and-aft weight transfer at the bearing surface at one side of the assembly may result in shimmy of the truck.

It is a further object of my invention to provide means whereby the relative movement between the bolster and the side frames is accommodated without opening a gap therebetween and without causing localized wear in the bearing surfaces through a localized fore-andeft shift ing of the load thereon. This is accommplished through use of a captive pillow block, the bottom surface of which is adapted to slide on the upper side of the side frame, and the upper surface of which is formed with a concave oavity which engages a cooperating convex projection on the bottom of the bolster. Accordingly, although the pillow block may rotate in a vertical plane together with the s ide frame at the curved contacting surfaces of the cavity and mating projection on the bolster, the sliding surfaces on the bottom of the pillow block and the side frame are always maintained in the same plane. In this construction, therefore, the desired geometry of movement is -zchieved but rigidly controlled to eliminate chatter between the parts and excessive wear.

A further object of my invention is generally to improve the construction and performance of lightweight railway trucks.

These and other objects and advantages of my invention will be set forth in the following description or will be evident therefrom or from practice of my invention.

In the drawings:

FIG. 1 is a perspective view of a preferred embodiment of the truck assembly;

FIG. 2 is a view of the truck assembly taken in elevation;

FIG. 3 is an end view of the truck assembly;

FIG. 4 is a view similar to that of FIG. 3 except that the forward wheel assembly, gearbox and braking mechanisms have been removed to more clearly show the positions of the various cooperating elements associated with the pivotal movement of the truck.

FIG. 5 is a fragmentary exploded view of the pillow block construction and arrangement;

FIG. 6 is an exploded View of a gimbal and pivot pin arrangement forming a swivel joint between the bolster and side frame-axle unit.

FIG. 7 is a side view of the torque arm connecting the axle mounted reduction gear to a side frame at a cushioned connection;

FIG. 8 is a fragmentary top view of the torque arm and its connections to the side frame;

FIG. 9 is a somewhat schematic illustration of yaw damping means to minimize high frequency pivotal oscillations of the running gear;

FIG. 10 is a somewhat schematic representation of a roll damping and biasing piston arrangement installed between the bolster and the laterally translating spring support arms;

FIG. 11 is a side view of the piston arrangement of FIG. 9;

FIG. 12 is a perspective view of an alternative lateral link structure providing support in shear for the air spring.

As shown in FIGS. 1, 2 and 3, the truck is made up of two longitudinally spaced side frames, 2 and 4, each having an inwardly-directed projection, 6 and 8 respectively, extending toward the vertical centerline of the truck assembly. A pair of wheel-axle assemblies, 10 and 12, are mounted in bearings provided at each end of the respective side frames, the mounting being effected to prevent any substantial longitudinal or transverse movement of the side frames with respect to one another but in resilient bushings as hereinafter discussed. Since the side frames are the basic load-carrying members of the assembly, they are necessarily of substantial rigidity and are provided with a flat upper surface on which the weight of the vehicle may be slidably supported.

The wheel-axle assemblies constitute the primary fixed connections between the respective side frames, and the side frames are free to rotate, to a limited extent, in a vertical plane, independently of one another. This capability is permitted through the use of a resilient axle bearing mounting which is not shown but which includes a resilient bushing surrounding a roller bearing to permit a limited floating of the bearing within the mounting. This concept is described in mycopending application Serial 4 No. 516,898, now Patent Number 3,382,017, issued May 7, 1968, and constitutes no part of the present invention except as a preferred element of the assembly. The resilient bushing further serves to isolate the vehicle from the high frequency vibrations generated by the passage of the metal wheels over the rails at high speed.

Power is individually supplied to each of the axles through axle-mounted gearboxes, 14 and 16, which receive power through Cardan shafts, 18 and 20, from a source external to the truck assembly.

A transverse bolster 22, on which the vehicle is suspended, is provided near the centerline of the truck, the ends of the bolster extending across the respective side frames. The bolster is connected to the side frame-axle subassembly in a pivotal connection whereby this subassembly is permitted to assume an angle of attack in a horizontal plane independent of that assumed by the vehicle itself. For this purpose, and as most clearly seen in FIGS. 4 and 6, theside frame projections 6 and 8 are terminated in flat, mutually-opposing surfaces, 30 and 32, a considerable distance from the longitudinal centerline of the truck. Cylindrical cavities, 34 and 36, are formed in the flat surfaces on a common axis with the cavity openings facing each other, and a centrally-locatedgimbal 38 is positioned therebetween. Thegimbal 38 includescylindrical end portions 40 and 42 which are closely and rotatably fitted into the respective cavities. In this construction, the planes of rotation of the side frames are always held parallel and their rotation in a vertical plane is effected about a single transverse axis common to both side frames. The gimbal also includes a thickened center portion 44 in which avertical opening 45 is provided which is adapted to closely receive apivot pin 46 which is suitably connected to the bolster, As assembled, the swivel member is held captive in and between the side frame projections and prevents any closure movement between them. Accordingly, the respective side frames 2 and 4 are permitted to rotate around the cylindrical end portions of the gimbal independently thereof and independently of each other, but only about a single transverse axis common to both side frames. Similarly, the side frame-axle subassembly, including the swivel member, is permitted to rotate in a horizontal plane around thepivot pin 46. It is, of course, contemplated that appropriate bearing surfaces will be provided in the usual manner between all of the relatively movable surfaces.

The bolster 22 is provided with a vertically-directed opening which is aligned with the opening in the swivel member, thepivot pin 46 extending through both of these openings. The braking, acceleration and other longitudinally-directed loads are taken through this pivotal assembly but no vertically-directed vehicle loads are imposed thereon, the Weight of the vehicle being taken through the bolster directly to the side frames as hereinafter described.

The bolster 22 is provided with a downwardly-directedconvex projection 50 at each end thereof in the vertical plane of the side frames. While this has been illustrated in FIGS. 4 and 5 as being effected by means of a bolted detail aflixed to the bottom of the bolster, the requisite projection may be formed integral with the bolster structure. Theprojection 50 engages in a matingconcave cavity 52 which is provided in apillow block 54 held captive between the bolster and the top of the confronting side frame. The pillow :block is adapted to slide on the side frame as the running gear pivots beneath the bolster and, for this purpose, aslidable surface 56 of Teflon or other material of predetermined frictional characteristics is preferably positioned between the confronting surfaces of the pillow block and the side frame on which it rests. Theconvex projection 50 has a slightly greater vertical dimension than that of theconcave cavity 52 whereby the side frame and mounted pillow block may rock in a vertical plane with respect to the bolster as the wheels on one side of the truck assembly negotiate irregularities in the track.

In other constructions where the bottom of the bolster rests directly on the side frame, a gap is opened between the bearing surfaces as the ends of side frames oscillate vertically, unless provision has been made therefor. In some constructions the side frame bearing surface is affixed to a resilient slide support which is embedded in the top surface of the side frame. In my construction, the bottom surface of the pillow block is always maintained in the same plane as that of the flat surface on the top of the side frame and no localized wear is caused in the respective bearing surfaces, the relative rocking motion being accommodated at the contacting semispherical surfaces within the pillow block cavity.

While the pillow block has been described in connection with a preferred construction, there is, of course, no reason why the cavity cannot be provided in the bolster and the projection on the pillow block to accommodate the rocking motion hereinbefore described. Similarly the contacting rocking surfaces need not be semispherical nor need they be provided between the bolster and the pillow block. In an alternative construction, the pillow block may be made slidable on the bolster, the rocking motion being accommodated at curved surfaces provided between the bottom of the pillow block and the top of the side frame.

In order to reduce truck shimmy resulting from high frequency hunting of the pivotal portion of the truck assembly at very high speeds, at yaw damper is preferably provided in the assembly. Such a yaw damping construction is shown somewhat schematically in FIG. 9. A longitudinally-directedplate 70 of substantial rigidity is provided on the bolster 22. A plurality ofhydraulic cylinders 71 and 72, oriented transverse to the truck assembly, are atiixed in a commonpivotal connection 73 to theplate 70 at one end and to the respective side frames 2 and 4 at their other ends, the movablehydraulic pistons 74 and 75 internal of each cylinder, translating laterally in response to horizontal movements of the bolster with respect to the side frames. Communication between the chambers formed within each of the cylinders by the pistons is effected throughconduits 76 and 77 andvariable orifices 78. The orifices are made variable as a function of speed by a signal fromspeed sensors 80. As the speed of the vehicle increases, the orifice size is reduced thereby offering greater resistance to the flow of fluid through the connecting conduits, providing in turn a greater stabilizing force between the bolster and the pivotal portion of the truck assembly. In actual practice it is anticipated that no damping will be required at speeds under 60 miles per hour and, therefore, the orifice will be fully open at this speed level.

Each of the axles is furnished with an axle mountedreduction gear through which power is transmitted to the axle and to the driving wheels. Power to the forward wheel-axle assembly 10 is provided byCardan shaft 18 which penetrates the bolster 22 through a suitable horizontal opening 79 (FIG. 6) or 81 (FIG. 4) provided therein. Since the gearboxes are unsupported except by the rotating shaft, means must be provided to accommodate the torque loads imposed on the gearbox as power is applied during acceleration. For this purpose, and as best seen in FIGS. 7 and 8 atorque arm 80 is bolted to thereduction gear 14 at one side and to theside frame 2 at the other end of the arm. The mounting of the torque arm to the side frame is resiliently effected in the conventional manner utilizing a plurality ofrubber bushings 82 surrounding aflange 84 affixed to the side frame and held captive between ametal washer 86 which is fixed to bolt 88 and ametal washer 90 Which is held in place bynut 92. In this manner rotation of the gearbox about its axle is prevented. Since the side frames oscillate in dilferent modes and independently of each other,

all torque-compensating connections from the gearbox must necessarily be made to a single side frame.

The braking mechanism carried by the truck is conveniently attached to the side frames. I prefer to employ both amagnetic track brake 94 and treadbrakes 96 and 98 on both sides of the truck. The construction and operation of those elements are well known in the art and further description relative thereto is, therefore, not included.

The resilient spring assembly by which the vehicle is supported from the bolster is preferably adapted to permit limited and controlled lateral translation of the vehicle body with respect to the running gear. To accomplish this translation and impart a bank to the vehicle on curves, two inwardly and upwardly directed spring support arms, 100 and 102, are mounted to the bolster in torsilastic bearings, 104 and 106, positioned at each end of the bolster. The torsilastic bearings are suitably attached to the ends of the bolster in a fore-and-aft orientation on supporting trunnions, and the support arms are affixed thereto to permit the translation of their free ends in a plane perpendicular to the longitudinal axis of the vehicle. The torsilastic bearings cause the vehicle body, through the action of the support arms, to assume a normal centered position. However, upon the application of centrifugal force to the lower part of the car as the vehicle rounds a curve or any other force tending to rotate the car about its longitudinal centerline, the free ends of the support arms move outward with respect to the curve. In so doing, the extremity of the free end of the inner support arm, 102 for example, moves toward the center of the truck and downward, carrying the inner side of the vehicle body with it. The free end of the outer arm, 100 for example, will straighten causing the outer side of the car to rise. By this concerted action of the arms the vehicle will be caused to bank. With the car in the banked position the respective torsilastic bearings will be placed under a torsion force which will restore the car to its centered position once the centrifugal force is removed.

Longitudinal loads are transmitted to the vehicle body through a pair of expandable drag links and 112 which are connected at one end to the end of the bolster and extend fore-and-aft therefrom. The links are universaljointed and are adapted at their free end to a connection with the vehicle body. While only one pair of drag links has been illustrated it will be understood that a similar drag link structure is provided at the other side of the truck assembly.

The drag link construction is basically the same as that taught in my prior Patent 2,935,031 and in operation confines the movement of the bolster with respect to the vehicle to a fixed vertical plane normal to the longitudinal axis of the vehicle. The body of the railway car may move freely in a vertical direction with respect to the bolster as a result of the compression and expansion of the pneumatic spring system. It may similarly move in a transverse direction, as hereinbefore discussed, as the car banks. Despite this freedom of movement, however, the body cannot move longitudinally with respect to the bolster.

In some installations means are incorporated in the assembly for damping the roll of the vehicle. Further, it may be advisable to provide means for biasing the vehicle laterally to compensate for variable forces tending to roll the car body as, for example, during operation of the train in a strong cross-wind. Such a roll damping and biasing construction is illustrated in FIGS. 10 and 11.

At each side of the assembly there is provided between the bolster 22 and the spring support arm 102 a damping piston and abiasing element 122. The damping piston, which in operation is functionally similar to the yaw clamping cylinders previously described, allows a lateral translation of the car body only upon the application of a sustained lateral force and thus eliminates any unwanted roll resulting from momentary laterally acting forces due mainly to trackage irregularities. By making theorifice 124 in the conduit 1.26 between the piston chambers variable as a function of speed, it is possible to maintain a constant roll rate at all train speeds. In an alternative arrangement, the operation of the roll damper could be made at the option of the engineer whereby all roll could be prevented during passage of the train through close quarters as, for example, between closelyabutting high level station platforms.

The operation of the biasing element is relatively evident. From asource 128 air is provided to the chamber formed beneath themoveable piston 130 at varying pressures depending upon the level of the side force to be equalized. It may be operable from the cab of the powered unit or automatically and may, in addition to the damping means, be utilized to prevent unwanted roll of the car body in a given direction if desired.

Lateral links, 108 and 110, are rotatably attached to the free end of the support arms at each side of the assembly and additionally connected to the vehicle body. The upper surface of each of the lateral links furnishes a mounting platform for the air springs 112 and 114 which resiliently support thevehicle body 116 in recesses provided therein at transversely spaced locations. The basic purpose of the lateral links is to maintain the base of the air spring in relatively fixed vertical alignment with the upper end of the spring to prevent the imposition of any shear loads upon the spring itself.

Although a single wishbone lateral link structure has been illustrated in the preferred embodiment, the same function may be provided by other means. An alternative construction providing shear support for the pneumatic spring is illustrated in FIG. 12. In this construction, lateral links, 140 and 142, at the bottom of the spring and similar links, 144 and 146, at the top of the spring are used to absorb the axial and transverse forces acting thereon while permitting free operation of the spring on a fixed vertical axis. The individual links extend in a generally horizontal plane from a common attachment at the spring to a spaced attachment with the vehicle body at their free ends. Accommodation for the requisite vertical movement of the spring is effected through the use of resilient mountings at both ends of the links in the conventional manner and the weight of the vehicle is taken through theupper arms 148 and 150, the springs, and the torsilasticspring support arm 102 as previously discussed.

A plurality of upstanding resilient supports 118 are provided in the space between the upper surface of the lateral links and the vehicle body to provide a backup support for the vehicle in the event of a malfunction in the air spring. These supports are formed to a considerable height and are preferably of varying resilience to furnish various degrees of support to the vehicle as a function of its downward movement.

While my invention has been primarily described in connection with a particular preferred embodiment, other modifications and alterations to the various elements of the assembly will be obvious from the teachings herein. The present embodiments are, accordingly, intended to be illustrative only.

I claim:

1. A truck assembly for a railway vehicle comprising:

a pair of transversely spaced rigid side frames each having an inwardly-directed projection of substantial thickness, the respective projections terminating in mutually-opposing, transversely-spaced surfaces near the transverse centerline of the truck. each of the opposing surfaces having a cylindrical cavity therein, the cavities lying on a common axis,

a pair of longitudinally-spaced wheel-axle assemblies rotatably and resiliently mounted in the side frames, the wheel-axle assemblies and associated mountings maintaining the side frames in position longitudinally and transversely of one another,

a gimbal held captive between the opposing surfaces of the side frame projections, the gimbal having cylindrical end portions closely and rotatably positioned in the respective cavities in the side frames and an enlarged central portion having a vertical opening therethrough,

a transverse bolster extending between and over each of the side frames and slidably supported thereon, the bolster having a downwardly directed pivot pin closely and rotatably received in the opening in the gimbal,

a plurality of drag links connected to the respective ends of the bolster and having connecting means at their free ends for attachment to the vehicle to permit free vertical and transverse movement between the bolster and the vehicle in a fixed plane perpendicular to the longitudinal axis of the vehicle,

an upwardly directed spring assembly connected to the bolster at each end,

and means for connecting the free end of the spring to the vehicle.

2. A truck assembly for a railway vehicle comprising:

a pair of transversely-spaced side frames,

a pair of longitudinally-spaced wheel-axle assemblies rotatably mounted in the side frames, the mountings preventing substantial longitudinal and transverse movement of the side frames with respect to one another,

a transverse gimbal member rotatably mounted in the side frames and held captive therebetween, the gimbal member having a vertical opening therethrough near the vertical centerline of the truck,

a transverse bolster extending between and over each of the side frames, the bolster having a downwardlydirected pivot pin closely and rotatably received in the opening in the gimbal member and a semispherical area on its bottom side at each end thereof in the vertical plane of the side frames,

a pillow block held captive between the confronting surfaces of the bolster and the side frame at each side of the truck, each pillow block having a flat lower surface slidably supported on the upper surface of the respective side frame and having a semispherical surface formed in its upper side which mates with the corresponding semispherical surface on the bottom of the bolster, the weight of the vehicle being taken through the bolster, the mating semispherical surfaces and the pillow block to the side frames, a rocking motion being permitted between the bolster and the pillow block at the semispherical surfaces,

a plurality of drag links connected to the respective ends of the bolster and having connecting means at their free ends for attachment to the vehicle to permit vertical and transverse movement between the bolster and the vehicle in a fixed plane perpendicular to the longitudinal axis of the vehicle,

a spring assembly at each side of the vehicle connected to the bolster at its end,

and means for connecting the free end of the spring to the vehicle.

3. A truck assembly according toclaim 2 in which:

a yaw damper is provided between the bolster and at least one of the side frames to reduce high frequency hunting of the running gear.

4. A truck assembly according toclaim 3 in which:

each spring assembly includes an air spring and supporting structure therefor which permits controlled lateral movement of the vehicle body with respect to the bolster to promote roll of the vehicle about a longitudinal axis as a result of centrifugal force when the vehicle negotiates a curve.

5. A truck assembly according toclaim 3 in which each spring assembly includes:

a torsilastic arm attached to the end of the bolster and extending upwardly and normally inwardly there from, the torsilastic arm being movable at its free end vertically and transversely in a plane perpendicular to the longitudinal axis of the truck assembly, and an upwardly-directed air spring aflixed to the free end of the torsilastic arm.

6. A truck assembly for a railway vehicle comprising:

a pair of transversely-spaced rigid side frames each having an inwardly-directed projection of substantial thickness, the respective projections terminating in mutually opposing transversely-spaced surfaces near the transverse centerline of the truck, each of the opposing surfaces having a cylindrical cavity therein, the cavities lying on a common axis,

a pair of longitudinally-spaced wheel-axle assemblies rotatably and resiliently mounted in the side frames, the wheel-axle assemblies and associated mountings maintaining the side frame in position longitudinally and transversely of one another,

a gimbal held captive between the opposing surfaces of the side frame projections, the gimbal having cylindrical end portions closely and rotatably positioned in the respective cavities in the side frames and an enlarged central portion having a vertical opening theretthrough,

a transverse bolster extending over each of the side frames, the bolster having a vertical opening therethrough on an axis coinciding with that of the opening provided in the gimbal and having a semispherical surface provided at its bottom side in the vertical plane of the side frames,

a pillow block held captive between the confronting surfaces of the bolster and the side frame at each side of the truck, each pillow block having a fiat lower surface slidably supported on the upper surface of the side frame and having a semispherical surface provided in its upper side with which the corresponding semispherical surface on the bolster mates to permit relative rocking motion between the pillow block and the bolster, the weight of the vehicle being carried through the bolster, the mating semispherical surfaces and the pillow blocks to the side frames,

a pivot pin closely-received in the openings provided in the bolster and the gimbal, the side frames and connected wheel-axle assemblies being permitted to pivot with respect to the bolster,

means for maintaining the bolster in a fixed plane longitudinally of the vehicle,

and means for resiliently supporting the vehicle from the bolster to permit controlled lateral and vertical movement of the vehicle body with respect to the bolster.

7. A truck assembly according toclaim 6 in which:

the semispherical surface provided on the bottom side of the bolster comprises a convex projection thereon,

and the semispherical surface provided in the upper side of the pillow block comprises a concave cavity into which the convex projection on the bolster is closely fitted.

8. A truck assembly according to claim 7 in which the means for maintaining the bolster in a fixed plane longitudinally of the vehicle includes:

a pair of expandable drag links connected to the free end of bolster at each side of the assembly and extending fore and aft therefrom, the free end of each drag link having means for connecting the respective drag links to the vehicle to maintain movement of the vehicle body with respect to the bolster in a vertical plane perpendicular to the longitudinal axis of the vehicle.

9. A truck assembly for a railway vehicle comprising:

a pair of transversely spaced side frames, each having a bearing area provided in its upper surface near its longitudinal midpoint,

a pair of longitudinally-spaced wheel-axle assemblies rotatably mounted in the side frames, the mountings fixedly positioning the side frames transversely of one another,

a gimbal rotatably mounted in the side frames near their longitudinal midpoint and extending therebetween, the gimbal being rotatable in a vertical plane parallel to the longitudinal axis of the truck assembly,

a transverse bolster extending over each of the side frames and pivotally connected to the gimbal, the bolster having a bearing area provided in its bottom surface in the plane of the side frames,

a pillow block held captive between the bearing areas on the bolster and the side frame at each side of the truck, each pillow block having a flat surface slidably contacting one of the bearing areas and a curved surface mating with a cooperating curved surface provided in the other bearing area to permit a longitudinal rocking motion therebetween, the Weight of the vehicle being taken through the bolster and pillow blocks at the curved surfaces to the side frames,

a plurality of drag links connected to the respective ends of the bolster and having connecting means at their free ends for attachment to the vehicle to permit vertical and transverse movement between the bolster and the vehicle in a fixed plane perpendicular to the longitudinal axis of the vehicle,

a torsilastic bearing connected to the bolster at each end thereof,

a support arm attached to each torsilastic bearing and biased thereby, each support arm normally extending upwardly and inwardly from the torsilastic hearing and being movable at its free end in a plane perpendicular to the longitudinal axis of the vehicle,

a vertically-oriented spring pivotally attached to the free end of each support arm,

means for attaching the free end of each spring to the vehicle,

and means for retaining the respective ends of each spring on a common axis to prevent the imposition of shear loads thereon.

10. The truck assembly ofclaim 9 in which:

a yaw damper is provided between one end of the bolster and at least one of the side frames to reduce high frequency hunting of the side frame and connected wheel-axle assemblies.

11. The truck assembly ofclaim 10 in which the means for maintaining the respective ends of each spring on a common axis includes:

a lateral link structure attached at one end to the bottom of the spring, the other end of the link structure having connecting means for attachment to the vehicle to maintain the bottom of the spring in a fixed position longitudinally and transversely of the vehicle.

12. A truck assembly for a railway vehicle comprising:

a pair of transversely spaced rigid side frames each having an inwardly-directed projection of substantial thickness, the respective projections terminating in mutually-opposing, transversely-spaced surfaces near the transverse centerline of the truck, each of the opposing surfaces having a cylindrical cavity therein, the cavities lying on a common axis,

a pair of longitudinally-spaced wheel-axle assemblies rotatably and resiliently mounted in the side frames, the wheel-axle assemblies and associated mountings maintaining the side frames in position longitudinally and transversely of one another,

a gimbal held captive between the opposing surfaces of the side frame projections, the gimbal having cylindrical end portions closely and rotatably positioned in the respective cavities in the side frames and an enlarged central portion having a vertical opening therethrough,

a transverse bolster extending between and over each of the side frames and slidably supported thereon,

1 1 the bolster having a downwardly directed pivot pin closely and rotatably received in the opening in the gimbal, means for accommodating a limited relative rocking motion between the confronting surfaces of the bolster and the respective side frames over a uniformly-loaded bearing area, plurality of drag links connected to the respective ends of the bolster and having connecting means at their free ends for attachment to the vehicle to permit free vertical and transverse movement between the bolster and the vehicle in a fixed plane perpendicular to the longitudinal axis of the vehicle, an upwardly directed spring assembled connected to the bolster at each end, and means for connecting the free end of the spring to the vehicle.

References CitedUNITED 10 ARTHUR L. LA POINT, Primary Examiner.

HOWARD BELTRAN,

Assistant Examiner.

US. Cl. X.R.

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