GB2269350A - A bogie truck for a railway vehicle - Google Patents

Abstract

A bogie truck comprises a pair of rigid side frames 10, front and rear axle sets connected to the side frames by a primary suspension, and a transverse bolster 11 extending between the side frames 11. The bolster 11 is connected to the side frames 10 by laminated metal and rubber V-shaped blocks 14. The transverse stiffness of the bolster 11 relative to the side frames 10 is not less than half its longitudinal stiffness. Track rods 22, resiliently connected to the bolster 11 and side frames 10 can also be used to increase the transverse stiffness. <IMAGE>

Description

'Improvements in or relatina to bogie trucks for rail vehicles" The invention relates to bogie trucks for rail vehicles and in particular to the suspension and frame arrangements for such bogie trucks.

The type of bogie truck to which the invention relates comprises a pair of rigid side frames, front and rear wheel and axle sets extending transversely between the side frames and connected thereto by primary suspension means, and a transverse bolster extending between the side frames and having a mounting for connection to the rail vehicle body, opposite ends of the bolster being connected to the respective side frames by intermediate suspension means.

The primary suspension means allow each wheel and axle set to perform limited vertical movement relatively to the side frames and also to be twisted relatively to the side frames about fore-and-aft extending axes.

The intermediate suspension means between the side frames and the transverse bolster allow the side frames to perform limited twisting movement relatively to one another about a horizontal transverse axis.

The articulation of the side frames permitted by such suspension arrangement allows the bogie truck to cope with irregularities in the track and, in particular, to accommodate track twist, i.e. sections of track where the two rails do not lie in exactly the same plane, thus requiring one side frame to twist at an angle to the other about a transverse axis as the bogie truck passes over that portion of track.

It is found that such suspension arrangements may be reasonably stable at speeds approaching about 60 m.p.h. However, where such bogie trucks are used on passenger rail vehicles, there is now an increasing requirement for the vehicles to travel regularly at speeds in excess of 60 m.p.h. It is found that at such speeds there is a tendency for the suspension system to become unstable and to begin to "hunt". The present invention sets out to provide an improved bogie truck of the kind first referred to where this problem may be alleviated or overcome. This is achieved by providing appropriate plan-view stiffness between the side frames and the bolster, thus overcoming the tendency to hunt, while providing appropriate side-view stiffness between the bolster and side frames to accommodate irregularities on the track.

"Plan-view stiffness", or "transverse stiffness", is the stiffness of the intermediate suspension in a horizontal direction at right angles to the track on which the bogie is to run. "Side-view stiffness", or "longitudinal stiffness", is the stiffness of the intermediate suspension in a horizontal direction and longitudinally of the track.

Hitherto, it has been the practice for the longitudinal stiffness to be more than double the transverse stiffness, for example in the ratio 30:8. We have discovered, however, that the tendency of the suspension to hunt may be substantially reduced, or eliminated altogether by substantially increasing the transverse stiffness of the intermediate suspension.

According to the invention, therefore, there is provided a bogie truck for a rail vehicle comprising a pair of rigid side frames, front and rear wheel and axle sets extending transversely between the side frames and connected thereto by primary suspension means, a transverse bolster extending between the side frames and having a mounting for connection to the rail vehicle body, opposite ends of the transverse member being connected to the respective side frames by intermediate suspension means, the transverse stiffness of the intermediate suspension means being not less than half the longitudinal stiffness thereof. Preferably, the transverse stiffness is not less than two-thirds of the longitudinal stiffness. For example, the ratio of longitudinal stiffness to transverse stiffness may be in the range of 30:18 to 30:22.A ratio of 30:20 is preferred, i.e. where the transverse stiffness is approximately two-thirds of the longitudinal stiffness.

Any convenient means may be provided for increasing the transverse stiffness of the intermediate suspension. For example, the intermediate suspension means may comprise resilient blocks disposed between abutments on the bolster and side frame respectively, the resilient blocks being angled to provide both longitudinal and transverse resilience. In this case the angle of such blocks to the longitudinal direction may be reduced, for example to about 45O or less, to increase the transverse stiffness.

Alternatively, the transverse stiffness may be increased in other ways, for example by pivotally connecting at least one track rod between each side frame and the bolster, each said track rod extending at an angle of less than 900 to the direction of travel of the bogie truck in use.

It is found that the provision of increased transverse stiffness may provide sufficient restraint to avoid the possibility of "lozenging" and to ensure adequate lateral stability for speeds of up to, say, 75 m.p.h. while still allowing the bogie frame to accommodate substantial track twisting and other irregularities without imparting massive stresses into the bogie frame.

The primary suspension means between each end of each wheel and axle set and a respective side frame may also comprise blocks of resilient material disposed between the front and rear sides respectively of an axle box at the end of the wheel and axle set and fixed front and rear abutments on the side frame.

Secondary suspension means may be provided for connection between the transverse member and the rail vehicle body.

The following is a more detailed description of embodiments of the invention, by way of example, reference being made to the accompanying drawings in which: Figure 1 is a diagrammatic side elevation of a bogie truck in accordance with the present invention, Figure 2 is a plan view of the bogie truck, the wheel and axle sets being omitted, Figure 3 is a plan view of an alternative embodiment; and Figure 4 is a horizontal section detail view of a part of the arrangement of Figure 3.

Referring to Figures 1 and 2 of the drawings, the bogie truck comprises two spaced rigid side frames 10 connected by a transverse bolster 11 to provide a generally H-shaped frame. The bolster 11 is connected to the underside of the rail vehicle body, indicated diagrammatically at 12, by a pivotal mounting (not shown) which permits limited pivotal movement of the bogie truck relatively to the vehicle body, about a vertical axis. Secondary suspension means, such as pneumatic air bags 13, are connected between the ends of the transverse member 11 and the underside of the vehicle body.

The ends of the bolster 11 are connected to the respective side frames 10 by intermediate suspension means indicated at 14.

The intermediate suspension means 14 comprise blocks of rubber or similar resilient material, mounted between opposed abutments on the transverse member 11 and side frames 10 respectively. As best seen in Figure 2 each block 14 is generally chevron-shaped as viewed in plan and is of laminated construction, comprising layers of rubber or like material sandwiched between and bonded to alternating metal plates. As best seen in Figure 1 the abutments 15 on the transverse member 11 are inclined downwardly towards corresponding upwardly inclined abutments on the side frames 10.

Extending between the side frames 10 fore-andaft of the bolster 11 are front and rear wheel axle sets 16. In conventional manner the ends of each axle are rotatable in bearings in an axle box 17 which is connected to the respective side frame 10 by primary suspension means 18.

The primary suspension means also comprise blocks of resilient material of generally laminated and chevron-shaped configuration, generally similar to the intermediate suspension elements 14. The blocks are bonded between upwardly inclined abutment faces on the axle boxes 17 and opposed downward inclined abutment faces provided on the respective side frame 10.

The described suspension system permits limited vertical movement of each wheel and axle set 16 relatively to the side frames 10 and also permits twisting of each wheel and axle set relatively to the side frames about a fore-and-aft extending axis. The intermediate suspension means 14 allows relative twisting movement between the side frames 10 about a transverse axis so as to accommodate twisting and other irregularities in the track.

In accordance with the present invention the intermediate suspension elements 14 are so designed that the transverse stiffness which they impart to the frame is not less than half the longitudinal stiffness, and is preferably about two-thirds of the longitudinal stiffness. The ratio between transverse stiffness and longitudinal stiffness may be achieved by any suitable method. For example, the ratio depends, at least in part, on the angle included by the chevron-shaped block of resilient material forming the intermediate suspension means. As the included angle is reduced, the ratio of transverse stiffness to longitudinal stiffness increases. Thus, the required ratio may be selected, in accordance with the present invention, by selecting chevrons of an appropriate angle which will normally be less than the angle of chevron blocks used hitherto.

In some cases, in order to achieve the required stiffness ratio, it may be necessary for the angle between the block to be reduced to 90O or less.

It may not be possible to accommodate such a small angle with chevron-shaped blocks of conventional design, but a similar effect may be achieved by replacing the continuous chevron-shaped blocks by two separate blocks inclined to one another by 90C or less, as viewed in plan Alternatively, the chevron-shaped blocks may be replaced by an end block between the side frame and bolster which alone provides most of the longitudinal stiffness, and side blocks disposed between the lateral sided of the side frame and an embracing extension of the bolster, the side blocks then providing most of the transverse stiffness of the suspension means. The side blocks may be entirely separate from the end block or may be integrally formed therewith.In another version the chevron-shaped blocks may have integral side extensions which are disposed between the sides of the side frames 10 and embracing extension flanges on the bolster 11 so as to provide further transverse stiffness in addition to the transverse stiffness provided by the chevron-shaped blocks 14. Other arrangements to achieve a similar increase in transverse stiffness will be apparent to a skilled person.

Although arrangements are preferred where the increased transverse stiffness is provided by design of the intermediate suspension means, other means may be provided to increase the transverse stiffness, and one such arrangement is shown in Figures 3 and 4.

Referring to Figures 3 and 4, it will be seen that, in this arrangement, the side frames 10 are connected to the bolster 11 by angled track rods 22.

The track rods 22 associated with each side frame 10 are generally symmetrically disposed with respect to the side frame and the bolster 11. The front track rods extend rearwardly as they extend inwardly away from the respective side frame 10 and the rear track rods extend forwardly as they extend inwardly away from the side frame. Each track rod extends at an angle of less than 90" to the direction of travel of the bogie truck along the rails.

As best seen in Figure 4, the outer end of each track rod 22 has an enlarged circular head 23 which is pivotal around a shaft 24 which is fixedly secured to the side frame 10 by bolts. The shaft 24 lies in a horizontal plane and extends at right angles to the track rod 22. At its inner end, each track rod 22 is pivotally connected to a fixed mounting on the transverse member 11 by a "spherilastic" flexible bearing.

As will be clearly seen from Figure 3, the angled arrangement of the track rods 22 means that they do not obtrude excessively into the space defined by the side frames 10 and transverse member 11, thus providing room for other equipment in that region.

As previously explained, the increased transverse stiffness of the suspension, in relation to its longitudinal stiffness, serves to stabilise the suspension system at high speeds and to inhibit "hunting".

Claims (8)

1. A bogie truck for a rail vehicle, comprising a pair of rigid side frames, front and rear wheel and axle sets extending transversely between the side frames and connected thereto by primary suspension means, and a transverse bolster extending between the side frames and having a mounting for connection to the rail vehicle body, opposite ends of the transverse bolster being connected to the respective side frames by intermediate suspension means, the transverse stiffness of the intermediate suspension means being not less than half the longitudinal stiffness thereof.

2. A bogie truck as claimed in claim 1, wherein the transverse stiffness is not less than two-thirds of the longitudinal stiffness.

3. A bogie truck as claimed in claim 1, wherein the ratio of longitudinal stiffness to transverse stiffness is in the range 30:18 to 30:22.

4. A bogie truck as claimed in any one of the preceding claims, wherein the intermediate suspension means comprises resilient blocks disposed between abutments on the bolster and side frame respectively, the resilient blocks being angled to provide both longitudinal and transverse resilience.

5. A bogie truck as claimed in any one of the preceding claims, wherein at least one track rod is pivotally connected between each side frame and the bolster, each said track rod extending at an angle of less than 900 to the direction of travel of the bogie truck in use.

6. A bogie truck as claimed in any one of the preceding claims, wherein the primary suspension means between each end of each wheel and axle set and a respective side frame comprises blocks of resilient material disposed between the front and rear sides respectively of an axle box at the end of the wheel and axle set and fixed front and rear abutments on the side frame.

7. A bogie truck as claimed in any one of the preceding claims, further comprising secondary suspension means for connection between the transverse member and the rail vehicle body.

8. A bogie truck substantially as herein described with reference to Figures 1 and 2, or Figures 3 and 4, of the accompanying drawings.