GB2173753A

GB2173753A - Rail vehicle bogie and vehicle for use in mines

Info

Publication number: GB2173753A
Application number: GB08607474A
Authority: GB
Inventors: Joseph Paul Bellis
Original assignee: Pikrose & Co Ltd
Current assignee: Pikrose & Co Ltd
Priority date: 1982-12-07
Filing date: 1986-03-26
Publication date: 1986-10-22
Also published as: GB2173753B; GB8607474D0

Abstract

The bogie includes a frame 9 and wheels 10 mounted on a respective support arm 14 pivotally attached through a torsion bush (19, Figure 5 not shown) whose stiffness is adjustable for different loads. A power means - hydraulic piston/cylinder unit 16 - interconnects the frame 9 and support arm 14 for raising or lowering a brake pad 18, which unit 16 is mounted in a lost-motion manner in a slot 17B for limited movement of the wheels to accommodate track gradients independently of the power means. During such independent movement the torsion bush acts to keep the wheels in contact with the track. <IMAGE>

Description

SPECIFICATION Improvements in and relating to railway equipment This invention relates to a rail vehicle bogie and to railway equipment, especially for use underground, including such a bogie.

Such equipment may be for carrying conventional locomotive hauled rolling stock, or may be of the type in which rail vehicles are clamped to a driven and hence tensioned haulage rope located between the rails of a track for the vehicles and extending in the direction of the track and in which (usually) a return run of the rope is located alongside the track.

Owing to various circumstances, the rolling stock or rail vehicles can become unstable on the track and, in consequence, de-railed. Such instability commonly occurs in regions of the track which are curved, especially if they are sharply curved. With ropehauled vehicles instability often occurs where there is a fall or depression in the ground beneath the track because the tension in the rope tends to lift it, and hence the vehicles, upwardly off the track.

The present invention provides a rail vehicle bogie for running on a track including a pair of spaced apart rails and comprising a frame and four railengaging wheels of which a leading and a trailing wheel are located at each side of the bogie and each of which is rotatable, in use, about an axis substantially parallel to the plane of the track, each wheel being carried by a support pivotally attached to the frame, at least one brake pad for engaging one of the rails and carried by the frame, power means operative to effect relative pivotal movement between the frame and the supports so that the brake pad(s) engage or disengage the rail(s), and trapping/guiding wheels each of which is associated with a respective rail-engaging wheel, each of which is carried by the support of its associated rail-engaging wheel and each of which is rotatable, when the brake pad(s) is disengaged from the rail(s), about an axis substantially perpendicular to the plane of the track.

The present invention also provides a rail vehicle for running on a track including a pair of spaced apart rails and comprising a frame and four railengaging wheels of which a leading and a trailing wheel are located at each side of the bogie and each of which is rotatable, in use, about an axis substantially parallel to the plane of the track, each wheel being carried by a support pivotally attached to the frame, at least one brake pad for engaging one of the rails and carried by the frame, power means operative to effect relative pivotal movement between the frame and the supports so that the brake pad(s) engage or disengage the rail(s), a respective power means connecting together each support and the frame, there being a lost-motion connection between the power means and at least one of its respective frame or its respective support, and resiliently yieldable means which become effective during lost-motion movement of the power means to resist disengagement of the rail-engaging wheels from the rails.

The present invention further provides a rail vehicle bogie for running on a track including a pair of spaced apart rails and comprising a frame and four rail-engaging wheels of which a leading and a trailing wheel are located at each side of the bogie and each of which is rotatable, in use, about an axis substantially parallel to the plane of the track, each wheel being carried by a support pivotally attached to the frame, at least one brake pad for engaging one of the rails and carried by the frame, and power means operative to effect relative pivotal movement between the frame and the supports so that the brake pad(s) engage or disengage the rail(s), wherein a respective power means connects together each support and the frame, each power means comprising a double-acting piston/cylinder assembly whereby pressurisation of the piston in one direction is used to lift the frame to a desired height above the track and pressurisation of the piston in the opposite direction is used to effect power braking.

The present invention still further provides a rail vehicle or railway equipment including a rail-vehicle bogie according to the invention.

Three forms of railway equipment constructed in accordance with the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure lisa diagrammatic side elevation of the first form of equipment, Figure 2 is an enlarged view of the bogie included in the vehicle of Figure 1 and shown in its nonbraked condition.

Figure 3 is an enlarged view of part of the bogie included in the vehicle of Figure 1 and shown in its braked condition, Figure 4 is an end elevation of the bogie of Figures 2and3, Figure 5 is a plan elevation of the bogie shown in Figures 2 to 4, Figure 6 shows part of a track including rails for receiving the railway equipment shown in Figures 1 to 5, Figure 7 is a diagrammatic partial side elevation of the second form of the equipment with the bogie in its non-braked condition, Figures 8 and 9 are similar views to Figure 7 and show how the bogie compensates for vertical deviation in the rails, Figures 10 and 11 are similar views to Figure 7 showing the bogie in its braked condition, in Figure 10 in a region of the track without trapping beams, and in Figure 11, in a region of the track with trapping beams, Figures 12 and 13 are side and plan views respectively of a power assembly used in the construction of Figures 7 to 11, and Figure 14 is a partial side elevation of the third form of the equipment.

Referring to the accompanying drawings, and first of all to Figures 1 to 6 the railway equipment includes a track having a pair of spaced apart flat bottomed railway rails 1, each having a heat 2, and each being mounted on sleepers 3 (See Figure 6).

Mounted on the rails 1, as indicated in Figure 1, is a vehicle 4 including identical leading and trailing bogies 5.

As shown in Figure 1 the vehicle 4 is connected to a haulage rope 6.

As indicated in Figures 2 to 5 the ends of some of the sleepers 3 carry an upwardly extending support arm 7, which arm, in turn, carries an I - section trapping beam 8. The arm 7 and beams 8 are arranged at those portions of the track where there is likely to be vehicle instability, for example at curves in the track as shown in Figure 6.

As will be seen from Figures 2 to 4, each bogie 5 comprises a frame 9 and, at each side of the bogie, leading and trailing pairs of vehicle supporting wheels 10, each supporting wheel having aflange 11 and a frusto-conical rail engaging periphery 12. Each supporting wheel 10 has an axis of rotation 13 extending transversely with respect to the direction of travel of the bogie along the rails 1 and substantially parallel to the plane of the track.

Each supporting wheel 10 is mounted on a respective support arm 14 pivotally attached through a torsion bush 19 about a suspension axis 15 to the main frame 9 of the bogie. The bush 19 may comprise two coaxial metal (e.g. steel) sleeves between which is bonded a resilient material (e.g.

rubber). The outer metal sleeve is secured to the main frame 9 and the inner sleeve can be turned (using a suitable tool which can be engaged, for example, in openings 19A - see Figure 2) relative to it to set the torsional stiffness of the bush 19. The bush 19 therefore gives suspension to the wheels 10 and can be adjusted for different loads. The support arms 14 are also pivotally connected about an axis 17 to an independent power means constituted by a hydraulic piston/cylinder unit 16.

As shown in inset in Figure 2 the position of axis 17 can vary as the bogie runs along the track, to allow for rail deviation.

During normal running of each bogie 5 along the track each piston/cylinder unit 16 is pressurised so that the support arms 14 and the frame 9 of the bogie are locked against relative pivotal movement apart from the limited movement resulting from movement of the axis 17. That movement can be achieved by mounting a transverse pin 17A, at one end of the piston rod of the unit 16, in horizontal slot(s) 17B in the frame, the horizontal extent of the slot(s) determining the degree ofthat movement. During normal running, the axis 17 ofthe pin 17A is in the central position within the slot 17B (as shown in inset Figure 2). Movement of the pin into the left-hand piston shown in inset in Figure 2 occurs if there is a sudden downward movement of the wheels 10 caused by vertical deviation in the rails.There is no tendency foranywheel 10to leavethe rails during orafterthat downward movement since the torsion bush 19 acts to force the arm 14 downwards (and hence to move the pin 17A along the slot 17B) and to hold the wheel against the rails. Movement of the pin 17A into the right-hand position shown in inset Figure 2 occurs if there is a sudden upward movement of the wheels 10 caused by vertical deviation of the rails. Again, there is no tendency for any wheel to leave the rails during or after that movement since the torsion bush 19 acts to resist upward movement of the arm 14 and to force the wheel against the rails.

At each side of the frame 9 of the bogie 5 and between the leading and trailing wheels 10 is carried a brake pad 18 which is engageable with a respective one of the rail heads 2 to act as a track brake for parking or in emergency purposes. The bogie 5 is shown in Figure 2 in its non-braked condition and in Figure 3 in its braked condition. A comparison of those two figures reveals that when fluid is exhausted from the hydraulic unit 16 the bogie frame 9 and the support 14 pivot relative to each other, the frame moving downwards under its weight until the brake pads 18 engage the rails 1. Downward movement of the frame to effect braking does not result in lifting of the vehicle supporting wheel 10 from the rails 1.Downward movernent of the frame 9 is resisted by the torsion bush 19 which acts, therefore, to force the wheel 10 onto the rails during that movement.

Associated with each vehicle supporting wheel 10 is a trapping/guiding wheel 20 which is rotatable about an axis substantially perpendicular to the plane of the track. During travel of the vehicle the tread portion 20A of the trapping/guiding wheel 20 engages an upright portion 8A of the trapping beam to effect bogie guidance around for example a curve in the track. The upper side 20B of each trapping/ guiding wheel, on the other hand, in engageable with a portion 8B of the trapping beam lying parallel to the track to prevent the supporting wheels 10 from disengaging the rails 1.

The trapping/guiding wheels 20 perform two main functions namely the guidance of the vehicle along the track and also prevention of lifting of the supporting wheels from the track. The trapping/ guiding wheels 20 also have a third function if the vehicle is braked in regions of the track provided with trapping beams. Thus, when the brake pads 18 are applied, by exhausting fluid from the hydraulic unit 16, each of the trapping/guiding wheels is tilted aboutthe axis of its associated supporting wheel 10 (as shown in Figure 3). In regions of the track provided with trapping beams, this results in the upper side 20B of each of the trapping/guiding wheels engaging that portion 8B of the trapping beam lying substantially parallel to the plane of the track.In this way, more force is derived from the torsion bush 19 acting to preventwheel lift. Further, the trapping/guiding wheels provide a braking effect in addition to that derived from the brake pads 18 engaging the rails.

Tilting of each trapping/guiding wheel 20 about the axis of its associated supporting wheel is achieved by rotatably mounting a support 21 for each trapping/guiding wheel about the axis of rotation 13 of its associated supporting wheel 10. As shown in the drawings, the support 21 for each trapping/guiding wheel is secured to the support arm 14 of its associated supporting wheel. Each support arm 14 carries two axles 22 and 23, the supporting wheel 10 being supported (through bearings 24) for rotation about axle 22 and the bogie frame 9 being pivotally supported (through the torsion bush 19) about the axle 23. The support 21 is mounted over and rotatable about one end of the axle 22.

Alternatively, the support arm 14 and the support 21 could be integral, for example they could be constituted by a single casting.

The sleepers 3 also carry, where appropriate, inclined rope pulleys 25 and rope trapping pulleys 26 for the rope 6.

Figures 7 to 13 illustrate a second form of railway equipment. This is basically similar to the equipment of Figures 1 to 6 but a different arrangement is used for compensating for different payloads and for compensating for vertical deviations in the rails. As in the case of Figures 1 to 6, a hydraulic piston/ cylinder assembly 101 is arranged between each support arm 102 and the frame 103 of the bogie 104.

Each arm 102 is pivotally secured to the frame 103 about an axis 105 and carries (in the same way as the equipment of Figures 1 to 6) a trapping/guiding wheel 106.

Each cylinder 107 of assembly 101 is mounted on an arm 102 and the piston rod 108 of that assembly is slidably mounted in a trunnion 109 secured to the frame 103. Mounted over the rod 108 is a stack of spring discs 110. A washer 111 is threaded onto the end of the rod 108 and a tube 112 is mounted over the spring discs. One end of the tube 112 (adjacent to the washer 111) is open and the other end is closed by a plate 113 abutting the trunnion 109 and having a central aperture through which the rod 108 passes.

The washer 111 is turned on to the end of the rod 108 to prestress the spring discs between the washer and the plate 113. The washer 111 is then held against further movement relative to the rod 108 by means of a pin 111A.

Mounted (see Figures 12 and 13) on the frame 103 between the leading and trailing rail-engaging wheels 150 at each side of the frame is an adjustable spindle 114 having a substantially horizontal axis.

Secured to opposite end portions of the spindle 114 are two arms 115. One end of each arm is attached to a lug 116 secured to the tube 112 associated with the piston/cylinder assembly of the leading railengaging wheel and the other end of each arm is attached to a lug 117 secured tothetube 112 associated with the piston/cylinder assembly of the trailing rail-engaging wheel. Each lug 116, 117 carries a pin 118 passing through an elongated slot 119 in the end portion of its associated arm 115. As shown in Figure 12 by turning the adjustment spindle 114 relative to the frame 103 the arms 115 are pivoted to effect relative movement of the tubes 112 (associated with the leading and trailing railengaging wheels) towards or away from each other.

That movement is made possible by movement of the pins 118 along their associated slots 119 (see Figure 12). Byturning and then fixing the spindle 114 relative to the frame 103, the angular position of the arms 115 and the axial position ofthetubes 112 can be set so that the spring discs 110 are stressed to increase or decrease their spring force to compensate for different payloads.

Figures 7 to 9 illustrate various unbraked conditions of the bogie. In Figure 7 - which illustrates normal running - the piston/cylinder unit 101, has been pressurised (by applying pressure fluid to the cylinder connection 120) to set the desired height of the bogie above the rails 121. Each piston/cylinder unit 101 effectively locks its associated arm 102 against pivotal movement (about axis 105) relative to the frame 103. By virtue of the spring arrangement (comprising the disc springs 110, the washer 111 etc.) the equipment does, however, despite the locking effect of the piston/cylinder unit 101 compensate for vertical deviations in the rails 121 and, at the same time, provides a spring force on the railengaging wheels 150 keeping them in engagement with the rails 121.

If there is a sudden upward movement of the leading rail-engaging wheels caused by vertical deviation in the rails then - as shown in Figure 8 the support arm 102 pivots upwards about the axis 105. That movement is resisted by the spring discs 110 which - owing to bodily movement of the cylinder and piston of the unit 101 to the right (as seen in Figure 8) - are further compressed by movement of the washer 111 to the right (as seen in Figure 8). Consequently, the wheels are forced downwards against the rails by the effect of the spring discs 110.

If, on the other hand, there is a sudden downward movement of the wheels 150 caused by vertical deviation in the rails then, as shown in Figure 9 - the support arm 102 pivots downwards about the axis 105. That results in bodily movement to the left (as seen in Figure 9) of the hydraulic piston/cylinder unit 101 which movement is assisted by expansion of the spring discs- as the washer 111 moves to the left.

Consequently, the rail-engaging wheels are forced into engagement with the rails by the spring discs 110 as they expand. Any subsequent tendency for the wheels 150 to lift is resisted by contraction of the springs (in a similar way to that described with reference to Figure 8).

As in the case of the construction of Figures 1 to 6, the arrangement of Figures 7 to 13 has a brake pad 122 arranged between the leading and trailing rail-engaging wheels 150 at each side of the frame 103. Each pad 122 is engageable with a respective rail 121. Figures 10 and 11 show the bogie 104 in two braked conditions- in Figure 10, in a region of the track without trapping beams and in Figure 11 in a region of the track with trapping beams.

Braking by the pads 112 is achieved by exhausting fluid (through the connection 120) from the hydraulic unit 101 which causes relative pivoting movement between the frame 103 and the support arms 102 about the axes 105, the frame 103 moving downwards under its weight until the pads engage the rails 121. Downward movement of the frame to effect braking does not result in lifting of the rail-engaging wheels 150 from the rails 121. Downward movement of the frame 103 is assisted by expansion of the spring 110. Once the piston of the unit 101 has completed its left-ward (as seen in Figure 10) stroke in the cylinder and has, therefore abutted the left-hand end of the cylinder any further relative pivotal movement between the arm 102 and frame 103 is resisted by contraction of the spring discs as the washer 111 is drawn to the right (in a similar way to that described with reference to Figure 8).

The trapping/guiding wheels 106 of the construc tion of Figures 7 to 13 perform the same two main functions as the trappingiguiding wheels 20 of the Figures 1 to 6 construction. Further, each trapping/ guiding wheel 106 is tilted about the axis of its associated rail-engaging wheel when the brake pads 122 are applied. In regions of the track provided with trapping beams 123 (see Figure 11), therefore, the upper side of each of the trapping/guiding wheels engages those beams (in the same way as the construction of Figures 1 to 6). In this way, additional force is derived from the spring discs 110 to resist lifting of the rail-engaging wheels. Further, the engagement of the trapping/guiding wheels 106 with the beams 123 provides a braking effect in addition to that derived from the pads 122 engaging the rails 121.

A third form of railway equipment is illustrated in Figure 14. This is basically the same as that shown in Figures 7 to 13 and similar parts have been identified by the same reference numbers raised by 100. The main difference is that in the construction of Figure 14 the cylinder unit 201 is ofthe double-acting type, having two fluid connections 220 and 224, and its cylinder is longer than that of the unit 101. As in the case of the Figures 1 to 6 and Figures 7 to 13 constructions, exhausting fluid (through the connection 220) from the unit 201 results in downward movement of the frame 203 to effect engagement between the brake pads 222 and the rails 221. At that stage, and unlike the construction of Figures 7 to 13 the cylinder unit 201 can be pressurised again by passing pressure fluid onto the cylinder through the connection 224. In that way the unit 201 attempts to effect further relative pivotal movement between the arms 202 and the frame 203 so that a powered braking effect is achieved by the pads 222 acting downwards on the rails 221 and the trapping/guiding wheels acting - in regions where trapping beams are provided (as in Figure 14) - upwardly on the trapping beams 223.

The piston/cylinder unit 201 of the Figure 14 construction could also be used with the construction of Figures 1 to 6 in place of its unit 16 in order to obtain a powered braking effect.

Claims

1. A rail vehicle bogie for running on a track including a pair of spaced apart rails and comprising a frame and four rail-engaging wheels of which a leading and a trailing wheel are located at each side ofthe bogie and each of which is rotatable, in use, about an axis substantially parallel to the plane of the track, each wheel being carried by a support pivotally attached to the frame, at least one brake pad for engaging one of the rails and carried by the frame, power means operative to effect relative pivotal movement between the frame and the supports so that the brake pad(s) engage or disengage the rail(s), and trapping/guiding wheels each of which is associated with a respective rail-engaging wheel, each of which is carried by the support of its associated rail-engaging wheel and each of which is rotatable, when the brake pad(s) is disengaged from the rail(s), about an axis substantially perpendicular to the plane of the track.

2. A rail vehicle bogie as claimed in Claim 1, in which the axis of rotation of each trapping/guiding wheel is fixed relative to the support of its associated rail-engaging wheel.

3. A rail vehicle bogie as claimed in Claim 1 or Claim 2, in which the axis of rotation of each trapping/guiding wheel intersects the axis of rotation of its associated rail-engaging wheel.

4. A rail vehicle bogie as claimed in any one of Claims 1 to 3, in which relative pivotal movement between the frame and the supports is limited by resiliently yieldable means.

5. A rail vehicle bogie as claimed in Claim 4, in which the resiliently yieldable means are adjustable to compensate for the total weight of the frame and any load carried by it.

6. A rail vehicle bogie as claimed in Claim 4 or Claim 5, in which the resiliently yieldable means comprises a torsion member associated with the pivotal connection between each support and the frame.

7. A rail vehicle bogie as claimed in Claim 4 or Claim 5, in which the resiliently yieldable means comprises a spring means associated with the power means.

8. A rail vehicle bogie as claim in any one of Claims 1 to 7, in which a respective power means connects together each support and the frame.

9. A rail vehicle bogie as claimed in Claim 8, in which each power means comprises a piston/cylinder unit.

10. A rail vehicle bogie as claimed in Claim 8 or Claim 9, in which the power means is hydraulically actuated.

11. A rail vehicle bogie as claimed in any one of Claims 8 to 10, in which there is a lost-motion connection between each power means and at least one of its respective frame or its respective support.

12. A rail vehicle including a bogie as claimed in any one of the preceding claims.

12. A rail vehicle bogie as claimed in Claim 1 and substantially as hereinbefore described with reference to, and as illustrated by Figures 1 to 6, Figures 7 to 13 or Figure 14 of the accompanying drawings.

13. A rail vehicle including a bogie as claimed in any one of the preceding claims.

14. Railway equipment comprising a track including a pair of spaced apart rails, a rail vehicle bogie as claimed in any one of the preceding claims mounted on the track and respective trapping beams arranged alongside at least a portion of the length of each rail, wherein, during normal travel of the bogie along the track, the circumferential portion of each trappinglguiding wheel is engageable with a portion of a respective beam to effect guidance of the bogie along the track and a portion of each trapping/ guiding wheel extending transversely to its axis of rotation is engageable with another portion of the beam to prevent lifting of its associated railengaging wheel from the track.

15. Railway equipment as claimed in Claim 14, wherein operation of the power means to effect braking causes tilting of each trapping/guiding wheel about the axis of its associated rail-engaging wheel whereby, in the region of the track provided with the beams, each trapping/guiding wheel is forced into engagement with the said other portion of the beam.

16. Railway equipment as claimed in Claim 14 or Claim 15, in which each beam has a portion, in cross-section, of inverted 'L' - shape.

17. Rai!way equipment as claimed in any one of Claims 14 to 16, in which each beam is 'I' - shaped in cross-section.

18. Railway equipment as claimed in any one of Claims 14to 17 and substantially as hereinbefore described with reference to, and as illustrated by Figures 1 to 6, Figures 7 to 13 or Figure 14 of the accompanying drawings.

19. A rail vehicle bogie for running on a track including a pair of spaced apart rails and comprising a frame and four rail-engaging wheels of which a leading and a trailing wheel are located at each side of the bogie and each of which is rotatable, in use, about an axis substantially parallel to the plane of the track, each wheel being carried by a support pivotally attached to the frame, at least one brake pad for engaging one of the rails and carried by the frame, power means operative to effect relative pivotal movement between the frame and the supports so that the brake pad(s) engage or disengage the rail(s), a respective power means connecting together each support and the frame, there being a lost-motion connection between the power means and at least one of its respective frame or its respective support, and resiliently yieldable means which become effective during lost-motion movement of the power means to resist disengagement of the rail-engaging wheels from the rails.

20. A rail vehicle bogie as claimed in Claim 19, in which the resiliently yieldable means are adjustable to compensate for the total weight of the frame and any load carried by it.

21. A rail vehicle bogie as claimed in Claim 19 or Claim 20, in which the resiliently yieldable means comprises a torsion member associated with the pivotal connection between each support and the frame.

22. A rail vehicle bogie as claimed in Claim 19 or Claim 20, in which the resiliently yieldable means comprises a spring means associated with each power means.

23. A rail vehicle bogie as claimed in any one of Claims 19 to 22, in which trapping/guiding wheels are provided each of which is associated with a respective rail-engaging wheel, each of which is carried by the support of its associated rail-engaging wheel, each of which is rotatable, when the brake pad(s) is disengaged from the rail(s), about an axis substantially perpendicular to the plane of the track, and the axis of rotation of each of which is fixed relative to the support of its associated rail-engaging wheel.

24. A rail vehicle bogie as claimed in any one of Claims 19 to 23 and substantially as hereinbefore described with reference to Figures 1 to 6, Figures 7 to 13 or Figure 14 of the accompanying drawings.

25. A rail vehicle including a bogie as claimed in any one of Claims 19 to 24.

26. Railway equipment comprising a track including a pair of spaced apart rails, a rail vehicle bogie as claimed in any one of Claims 19 to 25 mounted on the track and respective trapping beams arranged alongside at least a portion of the length of each rail, wherein, during normal travel of the bogie along the track, the circumferential portion of each trapping/guiding wheel is engageable with a portion of a respective beam to effect guidance of the bogie along the track and a portion of each trapping/ guiding wheel extending transversely to its axis of rotation is engageable with another portion of the beam to prevent lifting of its associated railengaging wheel from the track.

27; Railway equipment as claimed in Claim 26, wherein operation of the power means to effect braking causes tilting of each trapping/guiding wheel about the axis of its associated rail-engaging wheel whereby, in the region of the track provided with the beams, each trapping/guiding wheel is forced into engagement with the said other portion of the beam.

28. Railway equipment as claimed in Claim 26 or Claim 27, in which each beam has a portion, in cross-section, of inverted 'L' - shape.

29. Railway equipment as claimed in any one of Claims 26 to 28, in which each beam is 'I' shaped in cross-section.

30. Railway equipment as claimed in any one of Claims 26 to 29 and substantially as hereinbefore described with reference to, and as illustrated by Figures 1 to 6, Figures 7 to 13 or Figure 14 of the accompanying drawings.

31. A rail vehicle bogie for running on a track including a pair of spaced apart rails and comprising a frame and four rail-engaging wheels of which a leading and trailing wheel are located at each side of the bogie and each of which is rotatable, in use, about an axis substantially parallel to the plane of the track, each wheel being carried by a support pivotally attached to the frame, at least one brake pad for engaging one of the rails and carried by the frame, and power means operative to effect relative pivotal movement between the frame and the supports so that the brake pad(s) engage or disengage the rail(s), wherein a respective power means connects together each support and the frame, each power means comprising a double-acting piston/ cylinder assembly whereby pressurisation of the piston in one direction is used to lift the frame to a desired height above the track and pressurisation of the piston in the opposite direction is used to effect power braking.

32. A rail vehicle bogie as claimed in Claim 31 and substantially as hereinbefore described with reference to, and as illustrated by Figures 1 to 6, Figures 7 to 13 or Figure 14 of the accompanying drawings.

33. A rail vehicle including a bogie as claimed in Claim 31 or Claim 32.

34. Railway equipment comprising a track including a pair of spaced apart rails, a rail vehicle bogie as claimed in any one of Claims 31 to 33 mounted on the track and respective trapping beams arranged alongside at least a portion of the length of each rail, the bogie having trapping/guiding wheels each of which is associated with a respective rail-engaging wheel, each of which is carried by the support of its associated rail-engaging wheel, each of which is rotatable, when the brake pad(s) is disengaged from the rail(s), about an axis substantially perpendicular to the plane of the track, and the axis of which is fixed relative to the support of its associated rail-engaging wheel, wherein operation of the power means to effect braking causes tilting of each trapping/guiding wheel about the axis of its associated rail-engaging wheel whereby, the region of the track provided with the beams, each trapping/ guiding wheel is forced into engagement with the said other portion of the beam, and pressurisation of the piston of each piston/cylinder assembly in the said opposite direction effects power braking between the pad(s) and the rail(s) and between each trapping/guiding wheel and an associated trapping beam.

Amendments to the claims have been filed, and have the following effect: *(a) Claims 1 and 6 - 34 above have been deleted or textually amended.

*(b) New or textually amended claims have been filed as follows: CLAIMS

1. A rail vehicle bogie for running on a track including a pair of spaced apart rails and comprising a frame and four rail-engaging wheels of which a leading and a trailing wheel are located at each side of the bogie and each of which is rotatable, in use, about an axis substantially parallel to the plane of the track, each wheel being carried by a support pivotally attached to the frame, at least one brake pad for engaging one of the rails and carried by the frame, power means operative to effect relative pivotal movement between the frame and the supports so that the brake pad(s) engage or disengage the rail(s), a respective power means connecting together each support and the frame, there being a lost-motion connection between the power means and at least one of the frame or its respective support by virtue of which the frame and support are capable of a degree of relative movement independently of the power means, and resiliently yieldable means which become effective, during the independent relative movement of the frame and the support, to resist disengagement of the railengaging wheels from the rails.

6. A rail vehicle bogie as claimed in any one of Claims 1 to 5, in which each power means comprises a double-acting piston/cylinderassemblywhereby pressurisation ofthe piston in one direction is used to lift the frame to a desired height above the track and pressurisation of the piston in the opposite direction is used to effect power braking.

7. A rail vehicle bogie as claimed in any one of Claims 1 to 6, in which each power means is hydraulically actuated.

8. A rail vehicle bogie as claimed in any one of Claims 5 to 7, when in which the piston of each piston/cylinder assembly is lost-motion connected to the said one of the frame or its respective support.

9. A rail vehicle bogie as claimed in Claim 8 when appendantto Claim 4, in which each spring means is mounted over and held in place on the piston of its respective assembly.

10. A rail vehicle bogie as claimed in Claim 9, in which each spring means comprises a plurality of spring discs.

11. A rail vehicle bogie as claimed in any one of claims 1 to 10, wherein the power means, the lost-motion connection and the resilientlyyieldable means are substantially as hereinbefore described with reference to, and as illustrated by Figures 1 to 6, Figures 7 to 13 or Figure 14 of the accompanying drawings.