GB2330633A - Bogie truck for rail vehicles - Google Patents

Abstract

A bogie truck for a rail vehicle comprises a pair of spaced side frames 10, front and rear wheel and axle sets 15, 16 extending transversely between the side frames and rotatable in bearing assemblies 18 which are connected by primary suspension means 19 to the side frames and a transverse bolster 11 connected between the side frames and having a mounting for connection to the rail vehicle body. Each wheel 16 has coaxial annular braking surface on opposite sides thereof which are engageable by movable brake pads 28. All of the brake pads 28 are connected, through a mechanical linkage assembly 21, 22, 23, 43, 29, to a single fluid-actuated piston and cylinder assembly 33, whereby all of the brake pads 28 may be moved into or out of engagement with their associated braking surfaces by operation of the single assembly 23, which may be mounted on or off the bogie.

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 bogie trucks of this general type it is common to provide each wheel with a disc brake where movable brake pads on opposite sides ofthe wheel are engageable with annular braking surfaces disposed coaxially on opposite sides of the wheel. It is common practice for each disc brake to be actuated by a separate air cylinder which is located adjacent each wheel. There are thus provided four separate air cylinders on each bogie truck connected by air lines to a central braking control. Such arrangement is comparatively costly and the necessity of locating air cylinders close to the wheel may lead to difficulties in location of other components and also in maintenance. The present invention provides an alternative braking mechanism which may have advantage in certain types of bogie truck, 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, each wheel having a -coaxial annular braking surface which is engageable by a movable brake pad, all of said brake pads being connected, through a mechanical linkage assembly, to a single drive means, whereby all of the brake pads may be moved into or out of engagement with their associated braking surfaces by operation of said single drive means.

Said drive means may comprise a single fluid-actuated piston and cylinder assembly, such as an air cylinder assembly, and may be mounted on the bogie. For example it may be mounted on the transverse bolster of the bogie. Alternatively it may be mounted off the bogie.

Preferably each wheel is provided with two opposed brake pads which are movable, through the mechanical linkage, into and out of engagement with annular braking surfaces on opposite faces respectively of the wheel.

In this case the brake pads may be mounted on the ends of respective spaced pivoted calipers, the opposite ends of the calipers being connected to the rest of the mechanical linkage for movement towards and away from one another to effect engagement and disengagement of the brake pads with the braking surfaces.

The calipers on the two wheels adjacent the same side frame may be coupled through a common subsidiary linkage portion to said drive means.

The common subsidiary linkage portions connected to the calipers on the wheels adjacent the two side frames may be connected to a common drive means through a single final linkage portion.

In one embodiment of the invention the mechanical linkage assembly may include two operating members movably mounted for relative movement towards and away from one another under the action of said drive means, each said operating member being connected, by subsidiary mechanical linkages, to the brake pads engageable with the braking surfaces on two wheels, whereby relative movement between the operating members effects movement of the brake pads into or out of engagement with their respective braking surfaces. Preferably said operating members are movable in the foreand-aft direction relative to the bogie.

In the case where the drive means comprise a single fluid-actuated piston and cylinder assembly the assembly may have one part, e.g. the cylinder, mounted on one of said operating members and another part, e.g. the piston, connected to the other of said operating members, whereby movement of the piston relative to the cylinder moves the operating members towards or away from one another.

Said other part of the piston and cylinder assembly may be connected to said other operating member by a mechanical linkage.

In a preferred embodiment a double-ended lever arm is pivotally mounted on each operating member, one end of each lever arm being connected to the end of the other lever arm by a main link, the other end of the lever arm on the operating member on which the piston and cylinder assembly is mounted being connected to one of the parts of the assembly, and the other end of the lever arm on the other operating member being connected by a second link to said one operating member. For example, the second link may be connected to the cylinder of the piston and cylinder assembly.

Preferably said main link is a slack adjuster, i.e. a device which is automatically adjustable in length so as to alter the relative distance moved by the operating members in order to take up slack in the mechanical linkages and wear in the brake pads. Such devices are well known and will not therefore be described in detail.

The braking system according to this aspect of the invention may be applied to virtually any form of bogie, whether for freight or passenger use.

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 half plan view-of a bogie truck in accordance with the present invention, Figure 2 is an end view of the bogie truck, Figure 3 is a plan view of another bogie truck in accordance with the present invention, Figure 4 is a side elevation of the bogie truck of Figure 3, and Figure 5 is an end view of the bogie truck of Figure 3.

Referring to Figures 1 and 2, the bogie truck comprises two spaced side frames 10 connected by a transverse bolster 11 to provide a generally H-shaped frame, only one half of the symmetrical frame being shown in Figure 1. The bolster 11 is connected to the underside of the rail vehicle by an assembly 12 which 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 13 which is secured to the end of the bolster 11 or is integral with it. Between the side frames 10, fore-and-aft of the bolster 11, there extend wheel sets 14 each comprising an axle 15 on opposite ends of which are rigidly mounted flanged wheels 16. Inboard of each wheel 16 a bearing portion 17 of the axle 15 is rotatable in a bearing in an axle box 18.

A vertical helical compression spring assembly 19 is disposed between each axle box 18 and the end of the side frame 10. In known manner, the spring assemblies 19 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 19 constitute the primary suspension of the bogie truck and also provide lateral stiffness.

Associated with each wheel 16 is a brake assembly 20 comprising two callipers 21, 22 which overlie opposite sides of the wheel 16 and are pivotally connected by a cross link 23. The outer calliper 21 is pivotally mounted on the centre portion 13 of the side frame 10, as indicated at 24, whereas the inner calliper 22 is integral with a lever arm 25 which extends inwardly through apertures in the side frame 10. A short link 26 connects the end of the cross link 23 on which the calliper 22 is pivoted to the centre portion 13 of the side frame, as indicated at 27.

The ends ofthe callipers 21, 22 have brake pads 28 mounted thereon which are engageable with annular braking surfaces which are coaxial with the wheel 16 on opposite side faces thereof. The braking surfaces may be integrally formed on the wheel or may comprise separate annular components which are secured to the wheel.

The subsidiary linkages 21-27 are such that pivotal movement of each lever arm 25 away from the bolster 11 will bring the associated brake pads 28 into braking contact with the braking surfaces on the wheel, and movement of the lever 25 towards the bolster 11 will disengage the brake.

The brake assemblies 20 are operated by a main operating linkage 29 mounted between the side frames 10.

The linkage 29 comprises two operating cross members 30, 3 1. Opposite ends of each of the cross members 30, 32 are formed with flanges 44 which are slidably received in horizontal slots in inwardly projecting lugs 45 on the side frames 10, so that the members 30, 31 are slidable towards and away from one another along the fore-andaft axis of the bogie truck. The cylinder 32 of an air cylinder assembly 33 is fixedly mounted on the operating member 30 and is connected by a rigid link 34 to one end of a double-ended lever arm 35 which is pivotally mounted at 36 on the other operating member 31.

The opposite end of the lever arm 35 is pivotally connected at 37 to one end of an elongate slack adjuster 38. The opposite end of the slack adjuster 38 is pivotally mounted at 39 to a further double-ended lever 40 which is pivotally mounted at 41 on the first operating member 30. The opposite end of the lever 40 is pivotally connected at 42 to the end of the piston of the air cylinder assembly 33.

The flanges 44 at the outer extremities of the operating members 30, 31 are pivotally connected, by short links 43, to the lever arms 25 of the subsidiary linkages incorporating the brake callipers.

In order to apply the brakes, the air cylinder assembly 33 is actuated so as to extend the piston. The extension of the piston alters the geometry of the linkage provided by the four links 34, 35, 38 and 40 in a manner to move the operating members 30 and 3 1 away from one another. The link connections 43 between the operating members and the lever arms 25 cause all four lever arms 25 to pivot away from the bolster 11, thereby urging the brake pads 28 against the braking surfaces on the wheels 16, as previously described. Conversely, operation of the air cylinder assembly 33 to retract the piston moves the operating members 30, 3 1 towards one another again, swinging the levers 25 towards the bolster 11 so as to open the callipers and disengage the brakes.

The track adjuster 38 is of a well known kind in which the effective length of the adjuster 38 is automatically varied, during operation of the linkage, to take up any slack in the linkages or to compensate for wear in the brake pads 28.

In the alternative arrangement shown in Figures 3 to 5 the bogie truck comprises two spaced side frames 110 connected by a transverse bolster 111 to provide a generally H-shaped frame. The bolster 111 is connected to the underside of the rail vehicle body by an assembly 112 comprising a downwardly projecting part-spherical component 113 which engages within a corresponding socket component 114 on the bolster 111. The assembly 112 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 111 and the vehicle body.

Each side frame 110 comprises a central portion 115 which is secured to the ends of the bolster 111 by Huck bolts 1 16. The ends of the bolster 111 are provided with accurately machined surfaces which mate with corresponding accurately machined surfaces on the side frames 110 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 111 is of generally-I-section, comprising a central vertical web 11 la and upper and lower flanges 11 lib and 11 1c.

Between the side frames 110, fore-and-aft of the bolster 111, there extend wheel sets 117 each comprising an axle 118 on which are rigidly mounted flanged wheels 1 19.

Outboard of each wheel 119 the wheel set comprises a journal which is rotatable in a bearing in a bearing assembly 120.

As best seen in Figure 4, each bearing assembly 120 comprises an axle box 121, containing the bearing, mounted on a lower support frame 122. A vertical helical compression spring assembly 123 is disposed on each side of the axle box 121 with its lower end engaging in a recess in the lower frame 122 and its upper end connected to the underside of the side frame 110. In known manner the spring assemblies 123 are two-rate assemblies so as to provide different vertical stiffnesses for the tare and laden conditions ofthe vehicle. The helical compression spring assemblies 123 constitute the primary suspension of the bogie truck, The spring assemblies 123 also provide the lateral stifffiess for the bogie truck.

A vertical hydraulic damper 124 is disposed outboard of the axle box 121 and is pivotally connected between brackets 125, 126 on the lower frame 122 and the side frame 110 respectively. A fore-and-aft extending track rod 127 is pivotally connected between each bearing assembly and a mounting 128 on the lower part of each side frame 110.

As best seen in Figure 3, associated with each wheel 119 is a brake assembly 129 comprising two calipers 130 which overlie opposite sides of the wheel 119 and are pivotally connected to a cross link 131. The ends of the calipers 130 have brake pads 132 mounted thereon which are engageable with annular braking surfaces 133 which are coaxial with the wheel on opposite side faces thereof. The braking surfaces 133 may be integrally formed on the wheel or may comprise separate annular components which are secured to the wheel.

The calipers 130 are operated through a mechanical linkage. One end of each inboard caliper 130 is pivotally mounted to a fixed bracket 134 on the bolster 111. The outboard caliper 130 is pivotally connected to one end of a cross link 135 which is movable longitudinally of the bolster 111. The cross link 135 is connected by a short link 136 to one arm of a bell crank 137 which is pivotally mounted on the side frame, as indicated at 138. The opposite arm of each bell crank 137 is pivotally connected to a fore-and-aft extending link 139 and the two links 139 are connected by a further cross link 140. A further linkage 141 connects the cross link 140 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 ofthe links 139 to the left in Figure 3 which in turn pivots the bell cranks 137 so as to move the cross links 135 away from their associated fixed brackets 134. This operates the calipers 130 so as to close the brake pads 132 on to the annular braking surfaces on the wheels 119.

As may be seen from Figure 3, the outboard brake pad 132 and caliper 130 of each brake mechanism is located between the wheel 119 and the inner of the two helical springs 123, 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 121 from the wheel 119, since in such arrangements both springs 123 are the same distance from the wheel and the centre of the bearing lies in the same plane as the axes of the springs.

In the present arrangement, however, the plane containing the axes of the springs 123 and the centre of the bearing is inclined to the axis of the wheel set so that the outer spring 123 is closer to the wheel 119 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 (18)

1. 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, each wheel having a coaxial annular braking surface which is engageable by a movable brake pad, all of said brake pads being connected, through a mechanical linkage assembly, to a single drive means, whereby all of the brake pads may be moved into or out of engagement with their associated braking surfaces by operation of said single drive means.

2. A bogie truck according to Claim 1, wherein said drive means comprise a single fluid-actuated piston and cylinder assembly.

3. A bogie truck according to Claim 2, wherein said drive means comprise a single air-actuated piston and cylinder assembly.

4. A bogie truck according to any of Claims 1 to 3, wherein said drive means are mounted on the bogie.

5. A bogie truck according to Claim 4, wherein said drive means are mounted on the transverse bolster of the bogie.

6. A bogie truck according to any of Claims 1 to 3, wherein said drive means are mounted off the bogie.

7. A bogie truck according to any of the preceding claims, wherein each wheel is provided with two opposed brake pads which are movable, through the mechanical linkage, into and out of engagement with annular braking surfaces on opposite faces respectively of the wheel.

8. A bogie truck according to Claim 7, wherein the brake pads are mounted on the ends of respective spaced pivoted calipers, the opposite ends of the calipers being connected to the rest of the mechanical linkage for movement towards and away from one another to effect engagement and disengagement of the brake pads with the braking surfaces.

9. A bogie truck according to Claim 8, wherein the calipers on the two wheels adjacent the same side frame are coupled through a common subsidiary linkage portion to said drive means.

10. A bogie truck according to Claim 9, wherein the common subsidiary linkage portions connected to the calipers on the wheels adjacent the two side frames are connected to a common drive means through a single final linkage portion.

11. A bogie truck according to any of the preceding claims, wherein the mechanical linkage assembly includes two operating members movably mounted for relative movement towards and away from one another under the action of said drive means, each said operating member being connected, by subsidiary mechanical linkages, to the brake pads engageable with the braking surfaces on two wheels, whereby relative movement between the operating members effects movement of the brake pads into or out of engagement with their respective braking surfaces.

12. A bogie truck according to Claim 11, wherein said operating members are movable in the fore-and-aft direction relative to the bogie.

13. A bogie truck according to Claim 11 or Claim 12, wherein the drive means comprise a single fluid-actuated piston and cylinder assembly, the assembly having one part, mounted on one of said operating members and another part connected to the other of said operating members, whereby movement of the piston relative to the cylinder moves the operating members towards or away from one another.

14. A bogie truck according to Claim 13, wherein said other part of the piston and cylinder assembly is connected to said other operating member by a mechanical linkage.

15. A bogie truck according to Claim 13 or Claim 14, wherein a doubleended lever arm is pivotally mounted on each operating member, one end of each lever arm being connected to the end of the other lever arm by a main link, the other end of the lever arm on the operating member on which the piston and cylinder assembly is mounted being connected to one of the parts of the assembly, and the other end of the lever arm on the other operating member being connected by a second link to said one operating member.

16. A bogie truck according to Claim 15, wherein the second link is connected to the cylinder of the piston and cylinder assembly.

17. A bogie truck according to Claim 15 or Claim 16, wherein said main link is a slack adjuster, which is automatically adjustable in length so as to alter the relative distance moved by the operating members in order to take up slack in the mechanical linkages and wear in the brake pads.

18. A bogie truck substantially as hereinbefore described with reference to Figures 1 and 2, or Figures 3 to 5, of the accompanying drawings.