GB2330342A - Bogie trucks for rail vehicles - Google Patents

Abstract

A bogie truck for a rail vehicle comprises a pair of spaced side frames 10 connected by a bolster 11, and front and rear wheelsets 17 extending between the side frames and rotatable in bearing assemblies 20 which are connected by primary suspension means to the side frames. Each suspension means comprises a pair of helical compression spring assemblies 23 disposed on either side of the bearing. A vertical plane passing through the axes of the spring assemblies 23 is inclined to the axis of the bearing and associated wheel set, so that one of the spring assemblies is further from the surface of the adjacent wheel than the other, a brake pad 32 being located between that spring assembly and the wheel. Due to the inclination of the plane containing the spring assemblies, the bearing is itself closer to the wheel than would otherwise be the case, thus reducing the bending moment on the bearing.

Description

"Improvements in bogie trucks for rail vehicles" The invention relates to bogie trucks for rail vehicles, and in particular to bogie trucks of the kind comprising a pair of spaced side frames, front and rear wheel and axle sets extending transversely between the side frames and rotatable in bearing assemblies which are connected by primary suspension means to the side frames, and a transverse bolster connected between the side frames and having a mounting for connection to the rail vehicle body In such a bogie truck the primary suspension allows each wheel and axle set to perform limited vertical movement relative to the side frames and, more importantly, to be twisted relative to the side frames in a yaw sense, and to be able to translate laterally In a bogie truck of the kind referred to it is desirable for each bearing assembly to be located as close as possible to the adjacent wheel so as to minimise the bending moment exerted on the axle by the weight of the rail vehicle. One factor which limits how close the bearing assembly can be to the wheel is the necessity of locating the brake pad, and associated mounting components, close to the wheel. Commonly the primary suspension may include a pair of vertical helical compression springs which are connected between each bearing assembly and the associated side frame, on either side of the bearing. Consequently, it is usually necessary for a brake pad and associated components to be located between one of the suspension springs and the wheel In present arrangements this provides a limit to how close the bearing assembly can be to the wheel The present invention provides a novel arrangement whereby the bearing may be moved closer to the wheel than is possible in known arrangements According to the invention there is provided a bogie truck for a rail vehicle, comprising a pair of spaced side frames, front and rear wheel and axle sets extending transversely between the side frames and rotatable in bearing assemblies which are connected by primary suspension means to the side frames, and a transverse bolster connected between the side frames and having a mounting for connection to the rail vehicle body, wherein each primary suspension means comprises a pair of spring assemblies connected between each bearing assembly and the associated side frame, the two spring assemblies being disposed on either side of the bearing, and wherein a vertical plane passing through the spring assemblies is inclined to the axis of the bearing and associated wheel set, so that one of the spring assemblies is further from the surface of the adjacent wheel than the other.

Thus, in the case where each wheel has a coaxial annular braking surface which is engageable by a movable brake pad, the brake pad may be located between the wheel and that one of the spring assemblies which is further from the surface of the wheel.

Thus the distance between said one spring assembly and the wheel may be substantially the same as the corresponding distance in prior art bogie trucks of this type, but, due to the inclination of the plane containing the spring assemblies, the bearing is itself closer to the wheel than is the case in the prior art constructions, thus reducing the bending moment.

This aspect of the present invention may be applied to arrangements in which each bearing assembly and associated spring assemblies are located either inboard or outboard of the wheel The spring assemblies may have substantially vertical axes lying in said vertical plane. The vertical plane may also pass through the centre of the bearing assembly.

Each spring assembly may comprise a helical compression spring assembly.

Preferably each spring assembly is a two-rate assembly so as to provide different vertical stiffnesses for the tare and laden conditions of the rail vehicle The following is a more detailed description of an embodiment of the invention, by way of example, reference being made to the accompanying drawings in which: Figure 1 is a plan view of a bogie truck in accordance with the present invention Figure 2 is a side elevation of the bogie truck, and Figure 3 is an end view of the bogie truck Referring to the drawings: the bogie truck comprises two spaced side frames 10 connected by a transverse bolster 11 to provide a generally H-shaped frame The bolster I 1 is connected to the underside of the rail vehicle body by an assembly 1 2 comprising a downwardly projecting part-spherical component 13 which engages within a corresponding socket component 14 on the bolster 11. The assembly 12 allows the bogie to pivot freely, relative to the rail vehicle, when the vehicle is passing over undulating track. Further suspension means, not shown, are connected between the transverse bolster 11 and the vehicle body.

Each side frame 10 comprises a central portion 1 5 which is secured to the ends of the bolster 11 by Huck bolts 16. The ends of the bolster 11 are provided with accurately machined surfaces which mate with corresponding accurately machined surfaces on the side frames 10 so that each side frame, when such surfaces are brought into engagement, is accurately located in the required orientation with respect to the bolster. Not only does this ensure that the H-frame of the bogie will be square when assembled, with a minimum ofjigging, but it greatly facilitates the replacement of a side frame, or the bolster, since the replacement component will also be formed with the appropriate accurately machined surfaces so that, again, the components will fit together with a minimum of accurate jigging.

The bolster 11 is of generally I-section, comprising a central vertical web 1 la and upper and lower flanges 1 1b and 1 ic.

Between the side frames 10, fore-and-aft of the bolster 11, there extend wheel sets 17 each comprising an axle 18 on which are rigidly mounted flanged wheels 19.

Outboard of each wheel 19 the wheel set comprises a journal which is rotatable in a bearing in a bearing assembly 20.

As best seen in Figure 2, each bearing assembly 20 comprises an axle box 21, containing the bearing, mounted on a lower support frame 22 A vertical helical compression spring assembly 23 is disposed on each side of the axle box 2 1 with its lower end engaging in a recess in the lower frame 22 and its upper end connected to the underside of the side frame 10. In known manner the spring assemblies 23 are two-rate assemblies so as to provide different vertical stiffnesses for the tare and laden conditions of the vehicle. The helical compression spring assemblies 23 constitute the primary suspension ofthe bogie truck. The spring assemblies 23 also provide the lateral stiffness for the bogie truck.

A vertical hydraulic damper 24 is disposed outboard of the axle box 21 and is pivotally connected between brackets 25, 26 on the lower frame 22 and the side frame 10 respectively A fore-and-aft extending track rod 27 is pivotally connected between each bearing assembly and a mounting 28 on the lower part of each side frame 10.

As best seen in Figure 1, associated with each wheel 19 is a brake assembly 29 comprising two calipers 30 which overlie opposite sides of the wheel 19 and are pivotally connected to a cross link 31. The ends of the calipers 30 have brake pads 32 mounted thereon which are engageable with annular braking surfaces 33 which are coaxial with the wheel on opposite side faces thereof The braking surfaces 33 may be integrally formed on the wheel or may comprise separate annular components which are secured to the wheel The calipers 30 are operated through a mechanical linkage One end of each inboard caliper 30 is pivotally mounted to a fixed bracket 34 on the bolster 11. The outboard caliper 30 is pivotally connected to one end of a cross link 35 which is movable longitudinally ofthe bolster 11. The cross link 35 is connected by a short link 36 to one arm ofa bell crank 37 which is pivotally mounted on the side frame, as indicated at 38.

The opposite arm of each bell crank 37 is pivotally connected to a fore-and-aft extending link 39 and the two links 39 are connected by a further cross link 40. A further linkage 41 connects the cross link 40 to a driving device, such as an air cylinder, located away from the bogie, for example in the bottom part of the rail vehicle body.

In order to operate the brakes, the air cylinder or other device is actuated causing retraction of the links 39 to the left in Figure 1 which in turn pivots the bell cranks 37 so as to move the cross links 35 away from their associated fixed brackets 34 This operates the calipers 30 so as to close the brake pads 32 on to the annular braking surfaces on the wheels 19.

As may be seen from Figure 1, the outboard brake pad 32 and caliper 30 of each brake mechanism is located between the wheel 1 9 and the inner of the two helical springs 23, and sufficient space must be left between the inner spring and the wheel to allow for this part of the brake mechanism. Accordingly, in prior art arrangements this distance also determines the distance of the bearing and axle box 21 from the wheel 19, since in such arrangements both springs 23 are the same distance from the wheel and the centre of the bearing lies in the same plane as the axes of the springs According to the present invention, however, and as may be seen in Figure 1, the plane containing the axes of the springs 23 and the centre of the bearing is inclined to the axis of the wheel set so that the outer spring 23 is closer to the wheel 19 than the inner spring and the centre of the bearing is also closer to the wheel than the axis of the inner spring.

In a preferred arrangement the distance between the centres of the two bearings at the opposite ends of each wheel set may be reduced to 200 cm. Reduction of the distance between the bearing and the adjacent wheel reduces the bending moment applied to the axle due to the weight of the vehicle.

Claims (9)

1. CLAIMS A A bogie truck for a rail vehicle comprising a pair of spaced side frames, front and rear wheel and axle sets extending transversely between the side frames and rotatable in bearing assemblies which are connected by primary suspension means to the side frames, and a transverse bolster connected between the side frames and having a mounting for connection to the rail vehicle body, wherein each primary suspension means comprises a pair of spring assemblies connected between each bearing assembly and the associated side frame, the two spring assemblies being disposed on either side of the bearing, and wherein a vertical plane passing through the spring assemblies is inclined to the axis of the bearing and associated wheel set, so that one of the spring assemblies is further from the surface of the adjacent wheel than the other.
2. 2. A bogie truck according to Claim 1, wherein each wheel has a coaxial annular braking surface which is engageable by a movable brake pad, and wherein the brake pad is located between the wheel and that one of the spring assemblies which is further from the surface of the wheel.
3. 3 A bogie truck according to Claim 1 or Claim 2, wherein each bearing assembly is located outboard of the associated wheel.
4. 4 A bogie truck according to Claim 1 or Claim 2, wherein each bearing assembly is located inboard of the associated wheel.
5. 5. A bogie truck according to any of Claims 1 to 4, wherein the spring assemblies have substantially vertical axes lying in said vertical plane.
6. 6. A bogie truck according to any of the preceding claims, wherein the vertical plane passes through the centre of the bearing assembly.
7. 7. A bogie truck according to any of the preceding claims, wherein each spring assembly comprises a helical compression spring assembly.
8. 8. A bogie truck according to any of the preceding claims, wherein each spring assembly is a two-rate assembly so as to provide different vertical stiffnesses for the tare and laden conditions of the rail vehicle.
9. 9. A bogie truck according to Claim I and substantially as hereinbefore described with reference to the accompanying drawings.