GB2105802A

GB2105802A - Railway vehicle brake mechanisms

Info

Publication number: GB2105802A
Application number: GB08208844A
Authority: GB
Inventors: Geoffrey Albert Guppy
Original assignee: Underground Mining Machinery Ltd
Current assignee: Underground Mining Machinery Ltd
Priority date: 1981-03-25
Filing date: 1982-03-25
Publication date: 1983-03-30
Also published as: GB2105802B

Abstract

The vehicle has a frame 1,2 provided at each side with wheels 3 and at least one brake mechanism B having (a or) a pair of hydraulic piston-and- cylinder units 5 whose cylinders 5a are fixed to the frame, a brake pad 8 being attached to the movable piston or movable cylinder of each piston-and- cylinder unit 5, and disc springs 9 are provided for biasing pad 8 into contact with an upper surface of a respective rail R1 or R2 or section (S) running alongside the rail. In the four embodiments illustrated in the specification (others are disclosed) brake mechanism B also has a second brake pad 11 fixed to the frame, and positioned so as to lie adjacent to a lower surface of the respective rail R1 or R2 or section (S), so that when the hydraulic pressure is released the springs 9 apply pad 8 and then act on associated abutment member 10 to lift the frame and to bring the respective second brake pad 11 up into engagement with said lower surface of the respective rail or section and lift the wheels. In Figure 4, additional braking force is applied to pad 8 by the load platform. <IMAGE>

Description

SPECIFICATION Railway vehicle brake mechanism This invention relates to a railway vehicle having an improved track brake mechanism, and in particular to a mine rail vehicle having an improved calliper brake.

It is known to provide mine rail vehicles with calliper brake mechanisms. Usually, the bogies of such vehicles have respective calliper brake mechanisms at each side thereof. The known type of calliper brake mechanism has a hydraulic piston-andcylinder unit, each of the components of which is connected to a respective brake pad. The mechanism is mounted on the frame of the bogie in vertical slides, and heavy-duty springs are provided for biasing the two brake pads towards one another. In normal running conditions, the two brake pads are held apart (on opposite sides of a rail) by hydraulic pressure in the piston-and-cylinder unit. When the vehicle is to be braked, the hydraulic pressure is released, and the springs force the brake pads towards one another to grip the rail with a calliper action.In use, the heavy-duty springs first pull up the bottom brake pad (which is carried by the piston rod of the piston-and-cylinder unit). Then, the top brake pad (which is carried by the cylinder of the pistonand-cylinder unit) is pulled down against the force of light springs which normally hold the cylinder at the top of its slides. A brake mechanism of this type is described and claimed in the specification of our British Patent No 1 326406. The main disadvantage of this type of calliper brake mechanism is that the sliding parts (such as the piston rods) are exposed to the surrounding atmosphere when the brakes are off (that is to say most of the time in the case of emergency brakes). Thus, in the dirty conditions which prevail in mines, the assembly tends to clog, which results in inefficient braking or even brake failure.

The present invention provides a railway vehicle having a frame provided at each side with loadbearing wheels, the vehicle having at least one brake mechanism, the or each brake mechanism having a hydraulic piston-and-cylinder unit whose cylinder is fixed to the frame, a respective first brake pad being associated with the piston of the or each piston-andcylinder unit for reciprocal movement therewith, respective spring means being provided for biasing the or each first brake pad into contact with an upper surface of a respective rail, the or each spring means acting between the associated first brake pad and a respective abutment member fixed relative to the frame, and the or each brake mechanism having a second brake pad fixed to the frame and positioned so as to lie, in use, adjacent to a lower surface of a respective rail, whereby, when the hydraulic pressure in the or each piston-and-cylinder unit is released, the or each spring means forces the associated first brake pad down into contact with said upper surface of the respective rail, and then acts on the respective abutment member to lift the frame and to bring the associated second brake pad up into engagement with said lower surface of the respective rail.

The invention also provides a railway vehicle having a frame provided at each side with loadbearing wheels, the vehicle having at least one brake mechanism, the or each brake mechanism having a pair of hydraulic piston-and-cylinder units whose cylinders are fixed to the frame, a respective first brake pad being associated with the piston of each piston-and-cylinder unit for reciprocal movement therewith, respective spring means being provided for biasing each first brake pad into contact with an upper surface of a respective rail, each spring means acting between the respective first brake pad and a respective abutment member fixed relative to the frame, and the or each brake mechanism having a second brake pad fixed to the frame and positioned so as to lie, in use, adjacent to a lower surface of a respective rail, whereby, when the hydraulic pressure in the piston-and-cylinder units of the or each brake mechanism is released, the respective spring means force the associated first brake pads down into contact with said upper surface of the respective rail, and then act on the associated abutment members to lift the frame and to bring the respective second brake pad up into engagement with said lower surface of the respective rail.

By arranging that the calliper action first pushes down the first (top) brake pad(s), the associated spring means and sliding parts can be housed within the bodywork of the mechanism or the frame, so that, when the brakes are off (that is to say most of the time in the case of emergency brakes), ingress of foreign matter is prevented.

Advantageously, the frame is constituted by a pair of side members and a bridge joining the two side members, the side members supporting the loadbearing wheels, and the or each brake mechanism is associated with a respective side member. Preferably, the vehicle is provided with two brake mechanisms, each brake mechanism being associated with a respective side member. Where the brake mechanisms each have two piston-and-cylinder units, these units may be longitudinally spaced with respect to their side members.

Conveniently, the or each spring means is housed within a respective cylindrical bore formed in the associated side member, the or each bore being positioned between the associated piston-andcylinder unit and its first brake pad. Each bore provides adequate protection for its associated spring and sliding means, thereby reliably preventing the ingress of foreign matter such as dirt or coal particles.

The or each piston may be provided with a piston rod, the free end of which is attached to an end-plate which carries the respective first brake pad. In this case, the or each bore may be separated from the associated piston-and-cylinder unit by part of the associated side member, said side member part constituting the abutment member for the spring means associated with that bore, and the piston rod of that piston-and-cylinder unit passing through an aperture in the said side member part. Preferably, a respective set of heavy-duty disc springs constitutes the or each spring means.

Advantageously, the second brake pad of the or each brake mechanism is mounted on a respective carrier plate, and the or each carrier plate is mounted on a respective pair of longitudinally-spaced brackets fixed to the frame by means of a respective pair of vertically-spaced pins which pass through aligned apertures in the associated carrier plate and the associated brackets. Preferably, the brackets associated with the carrier plate of the or each brake mechanism are attached to a respective side member.

In a preferred embodiment, the or each first brake pad and the or each second brake pad is aligned with the load-bearing wheels at one side of the vehicle. In this case, the or each brake mechanism is arranged to grip one of the rails along which the vehicle runs.

Alternatively, the or each first brake pad and the or each second brake pad is outwardly off-set with respect to the load-bearing wheels at one side of the vehicle. Here, the or each brake mechanism is arranged to grip a special rail which is positioned outside the rail track.

In another preferred embodiment, the or each first brake pad is aligned with the load-bearing wheels at one side of the vehicle, and the or each second brake pad is outwardly off-set with respect to the loadbearing wheels at one side of the vehicle. In this case, the or each first brake pad is arranged to engage one of the rails along which the vehicle runs, and the or each second brake pad is arranged to engage a special rail which is positioned outside the rail track.

Advantageously, the bridge is provided with a bridge support shaft at each end thereof, the bridge support shafts being mounted in apertures in the side members. Preferably, said apertures in the side members are elongate in the vertical direction, and each side member is provided with a respective slide plate, each slide plate being mounted in a vertical slideway formed in the associated side member, each slide plate being engageable with the end portion of the adjacent bridge support shaft, and each slide plate being operatively associated with the piston(s) of the piston-and-cylinder unit(s) associated with that side member. Conveniently, each slide plate is engageable with the end plate(s) of the piston rod(s) of the piston-and-cylinder unit(s) associated with that side member. This arrangement is advantageous in that it results in weight-enhanced braking.

The invention also provides a railway vehicle having a frame provided at each side with loadbearing wheels, the frame being constituted by a pair of side members and a bridge joining the two side members, the side members supporting the load-bearing wheels, and a brake mechanism associated with each of the side members, each brake mechanism having a hydraulic piston-and-cylinder unit whose cylinder is fixed to the frame, a respective brake pad being associated with the piston of each piston-and-cylinder unit for reciprocal movement therewith, respective spring means being provided for biasing each brake pad into contact with an upper surface of a respective rail, each spring means acting between the associated brake pad and a respective abutment member fixed relative to the frame whereby, when the hydraulic pressure in the piston-and-cylinder units is released, the spring means force the brake pads down into contact with said upper surfaces of the rails.

Four forms of mine rail vehicle bogie, each incorporating a brake mechanism constructed in accordance with the invention, will now be described, by way of example, with reference to the accompanying drawings, in which: Figure lisa part-sectional side elevation of the first form of bogie; Figure 2 is a plan view of one side of the bogie of Figure 1; Figure 3 is a part-sectional end elevation of the bogie of Figures 1 and 2; Figure 4 is a part-sectional side elevation of the second form of bogie; Figure 5 is a schematic end elevation of part of the third form of bogie; and Figure 6 is a part-sectional end elevation of the fourth form of bogie.

Referring to the drawings, Figures 1 to 3 show a bogie for a mine rail vehicle (not shown). Mine rail vehicles usually have a load platform supported, at each end, by a bogie. Each of these bogies may be of the type shown in Figures 1 to 3. The bogie runs on a track constituted by a pair of rails R1 and R2 (see Figure 3). The rail R1 is a standard flat-bottom rail, and the rail R2 is an asymmetric rail. The two rails R1 and R2 are shown in the same figure to illustrate that the bogie can run either form of rail. Obviously, in use, both rails of a given track will be of the same type.

The bogie has a frame constituted by a pair of side members 1 and a bridge 2 joining the two side members. Each member 1 supports a pair of aligned load-bearing, flanged wheels 3. The bridge 2 is supported by the side members 1 via bridge support shafts 4 provided at the ends of the bridge. Each side member 1 is provided with a brake mechanism B (only one of which is shown in detail). Each brake mechanism B has a pair of longitudinally-shaped, hydraulic piston-and-cylinder units 5. Each pistonand-cylinder unit 5 has a cylinder 5a fixed to the top of the associated side member, a piston Sb reciprocable within the cylinder, a working chamber Sc connectible to a source of pressurised hydraulic fluid (not shown), and a piston rod 5d attached to, and extending downwardly from, the piston. Beneath each of the piston-and-cylinder units 5, a respective cylinder bore 6 is formed within the respective side member 1. Each piston rod Sdextendsthrough its associated bore 6, a respective end plate 7 being attached to the free end of each piston rod. Each end plate 7 carries a top brake pad 8. A set of heavy-duty disc springs 9 is provided within each of the bores, the disc springs surrounding the associated piston rod 5d. Each set of disc springs 9 acts against the end plate 7 of the associated piston rod 5d, and is backed by an abutment member 10 constituted by that part of the associated side member which separates the associated bore 6 and cylinder 5a. Each piston rod 5d passes through an aperture in its associated abutment member 10. The springs 9 thus bias the top brake pads 8 down towards the rails R1 or R2.

Each brake mechanism B also has a bottom brake pad 11 which is supported, in a fixed position relative to the associated side member 1, by a carrier member 12 held in place by a pair of verticallyshaped pins 13 and a pair of longitudinally-spaced brackets 14. The brackets 14 associated with a given brake pad 11 are fixed to the respective side member 1 and the pins 13 pass through aligned apertures in the brackets and the associated carrier member 12 to hold that brake pad in said fixed position. The bottom brake pads 11 are so fixed that, in the brakes-off position shown in Figure 3, they lie under, and are spaced a small distance from, the undersides of the rails R1 or R2.

When the mine rail vehicle is travelling along the track, each of the brake mechanisms B is in the brakes-off position. In this position (see Figure 3), the working chambers Sc of the piston-and-cylinder units 5 are pressurised so as to overcome the force of the springs 9. Consequently, the pistons Sb are forced upwardly, so that the top brake pads 8 form a small clearance with the rails R1 or R2. When the vehicle is to be braked, the hydraulic pressure is released from the working chambers 5c, so that the springs 9 force the brake pads 8 hard down onto the top surfaces of the rails R1 or R2. The rails R1 or R2 then constitute abutments for the springs 9 which act upwards on the abutment members 10.This causes the side members 1 to lift slightly so as to bring the bottom brake pads 11 into engagement with the undersides of the rails R1 or R2. Thus, the brake mechanisms B exert a clamping or calliper action on the rails R1 or R2, which causes effective braking.

Figure 4 shows a bogie having modified braking mechanisms B' (only one of which is shown). The braking mechanism B' is basically the same as the braking mechanism B of Figures 1 to 3, apart from a modification which results in enhanced braking.

Accordingly, like reference numerals have been used for similar parts, and only the modification will be described in detail. Thus, the bridge support shafts 4 of this bogie are mounted in respective elongate apertures 4a in the side members 1, and each bogie support shaft is supported by a slide plate 4b. Each slide plate 4b is mounted in a vertical slideway 4c formed in the associated side member 1. Each slide plate 4b is attached to an end plate 4dwhich has shoulders 4e (only one of which can be seen in Figure 4) at its two longitudinal ends. The shoulders 4e of each slide plate 4b mate with complementary shoulders 7a formed on the adjacent edges of the two associated end plates 7. In the brakes-off position (shown in Figure 4), the hydraulic pressure in the piston-and-cylinder units 5 hold the top brake pads 8 clear of the rails as described above with reference to Figures 1 to 3.At the same time, the slide plates 4b are held at the top of their slideways 4c, which in turn holds the bridge support shafts 4 in a raised position. As the shafts 4 support the vehicle which load platform (not shown) via the bridge (not shown, but similar to the bridge 2 of Figures 1 to 3), this results in the load platform being held in a raised position. When the hydraulic pressure is released from the piston-and-cylinder units 5, the springs 9 force the brake pads 8 hard down onto the top surfaces of the rails. At the same time, the shafts 4 and the slide plates 4b are forced down under the weight of the load platform. This applies an addition al braking force to the brake pads 8, this additional braking force being proportional to weight of the load platform and its payload.Thus, the greater the payload, the greater is the additional braking force, so that an additional safety feature is built in to this modified braking arrangement. Obviously, as with the embodiment of Figures 1 to 3, once the top brake pads 8 engage the top surfaces of the rails, the force of the springs 9 is directed upwardly to lift the side members 1 up to bring the bottom brake pads (not shown, but similar to the brake pads 11 of Figures 1 to 3) into engagement with the undersides of the rails. Here again, therefore, a calliper braking action results.

It will also be apparent that the bogie of Figure 4 has unflanged wheels 3' for running on coolie-car track. The bogie is, therefore, provided with trapping wheels 15 for holding the bogie on the track.

Figure 5 shows another modified form of braking arrangement. Here again like reference numerals are used for like parts, and only the modifications will be described in detail. Basically, the braking mechanism B" shown in Figure 5 can be the same as the mechanism B of Figures 1 to 3 or the same as the mechanism B' of Figure 4. The only difference between this embodiment and the two earlier embodiments is that the entire mechanism B" is laterally off-set away from the centre-line of the bogie, so that its top and bottom brake pads 8 and 11 act on the top and underside surfaces respectively of the top flange F of a C-shaped rolled channel section S which runs alongside the rail R. It would also be possible to off-set the brake mechanism either inwardly or upwardly to engage with rails positioned in these directions.

The arrangement shown in Figure 5 could be modified by having, instead of the rolled channel section, an angle section or joist.

Figure 6 shows another form of modified form of braking arrangement. Here again, like reference numerals are used for like parts, and only the modifications will be described in detail. Basically, the braking mechanism B"' shown in Figure 6 is identical with the mechanisms B, B' and B", apart from the fact that the bottom brake pad 11 of the brake mechanism B"' is arranged to engage against the underside of a C-shaped rolled channel section S which runs alongside the rail R. Obviously, each of the side members 1 is provided with a respective braking mechanism B"', though only one of these mechanisms is shown in Figure 6. Braking action is, therefore, achieved by forcing the top brake pads 8 down against the heads of the rails R. This results in the vehicle being lifted, which causes the bottom brake pads 11 to move up into engagement with the undersides of the channel sections S. Thus, each of the brake mechanisms B"' exerts a clamping or calliper action between its associated rail R and channel section S.

In this modified arrangement, the brake mechan isms B"' can operate as normal drop-down brakes where the vehicle is running along a track which is not provided with the channel section S, that is to say where the track has a relatively small gradient.

Where a steeper gradient is encountered, the channel section S would be installed, whereupon the effectiveness of the braking mechanisms B"' would be increased by the calliper action produced between the channel sections and the rails R.

In each of the embodiments described above, the lifting of the bottom brake pads, which gives rise to the calliper action, also lifts the bogie wheels just out of contact with the rails (the wheels being fixed to the side members.

It will be apparent that the brake mechanisms described above are all fail-safe. Thus, if the hydraulics fail for any reason, the springs automatically apply the brakes.

The main advantage of the brake mechanisms described above is that their springs 9 and their sliding parts (piston rods 5d) are completely housed within the bores 6, so that the ingress of foreign matter is prevented. This results in more efficient braking than was possible with known calliper brakes, and prevents the possibility of brake failure.

Another advantage of this type of brake mechanism arises from the method of securing the lower brake pads 11 to the side members 1. Thus, by attaching the carrier plate 12 associated with the brake pads 11 using pairs of vertically-shaped pins 13, it is relatively easy to remove the lower pin so that the entire carrier plate 12 can be pivoted upwards by up to 180 degrees. Not only does this enable the lower brake pads 11 to be readily accessible for inspection and/or replacement, but it also exposes the top plate pads 8 for inspection.

It will be appreciated that the brake mechanisms described above could be modified in a number of ways. For example, where calliper braking is not required, the bottom brake pads and associated parts could be dispensed with, in which case the brake mechanisms would operate as simple dropdown brakes. The real advantage of this is that the same basic construction can be used for both drop-down brakes and calliper brakes, so that constructional and storage costs are reduced.

It will also be appreciated that the brake mechanisms could be modified by turning the piston-andcylinder units "upside-down", that is to say be arranging for their pistons to be fixed to the side members, and by providing the top brake pads on their movable cylinders. The appended claims should be construed in this light.

Claims

1. A railway vehicle having a frame provided at each side with load-bearing wheels, the vehicle having at least one brake mechanism, the or each brake mechanism having a hydraulic piston-andcylinder unit whose cylinder is fixed to the frame, a respective first brake pad being associated with the piston of the or each piston-and-cylinder unit for reciprocal movement therewith, respective spring means being provided for biasing the or each first brake pad into contact with an upper surface of a respective rail, the or each spring means acting between the associated first brake pad and a respective abutment member fixed relative to the frame, and the or each brake mechanism having a second brake pad fixed to the frame and positioned so as to lie, in use, adjacent to a lower surface of a respective rail, whereby, when the hydraulic pressure in the or each piston-and-cylinder unit is released, the or each spring means forces the associated first brake pad down into contact with said upper surface of the respective rail, and then acts on the respective abutment member to lift the frame and to bring the associated second brake pad up into engagement with said lower surface of the respective rail.

2. A railway vehicle having a frame provided at each side with load-bearing wheels, the vehicle having at least one brake mechanism, the or each brake mechanism having a pair of hydraulic pistonand-cylinder units whose cylinders are fixed to the frame, a respective first brake pad being associated with the piston of each piston-and-cylinder unit for reciprocal movement therewith, respective spring means being provided for biasing each first brake pad into contact with an upper surface of a respective rail, each spring means acting between the respective first brake pad and a respective abutment member fixed relative to the frame, and the or each brake mechanism having a second brake pad fixed to the frame and positioned so as to lie, in use, adjacent to a lower surface of a respective rail, whereby, when the hydraulic pressure in the pistonand-cylinder units of the or each brake mechanism is released, the respective spring means force the associated first brake pads down into contact with said upper surface of the respective rail, and then act on the associated abutment members to lift the frame and to bring the respective second brake pad up into engagement with said lower surface of the respective rail.

3. A railway vehicle as claimed in claim 1 or claim 2, wherein the frame is constituted by a pair of side members and a bridge joining the two side members, the side members supporting the loadbearing wheels, and wherein the or each brake mechanism is associated with a respective side member.

4. A railway vehicle as claimed in claim 3, wherein the vehicle is provided with two brake mechanisms, each brake mechanism being associated with a respective side member.

5. A railway vehicle as claimed in claim 4 when appendant to claim 2, wherein the two piston-andcylinder units of each brake mechanism are longitudinally spaced with respect to their side members.

6. A railway vehicle as claimed in any one of claims 3 to 5, wherein the or each spring means is housed within a respective cylindrical bore formed in the associated side member, the or each bore being positioned between the associated pistonand-cylinder unit and its first brake pad.

7. A railway vehicle as claimed in any one of claims 1 to 6, wherein the or each piston is provided with a piston rod, the free end of which is attached to an end-plate which carries the respective first brake pad.

8. A railway vehicle as claimed in claim 7 when appendant to claim 6, wherein the or each bore is separated from the associated piston-and-cylinder unit by part of the associated side member, said side member part constituting the abutment member for the spring means associated with that bore, and the piston rod of that piston-and-cylinder unit passing through an aperture in said side member part.

9. A railway vehicle as claimed in claim 6 or claim 8, wherein a respective set of heavy-duty disc springs constitutes the or each spring means.

10. A railway vehicle as claimed in any one of claims 1 to 9, wherein the second brake pad of the or each brake mechanism is mounted on a respective carrier plate, and the or each carrier plate is mounted on a respective pair of longitudinally-spaced brackets fixed to the frame by means of a respective pair of vertically-spaced pins which pass through aligned apertures in the associated carrier plate and the associated brackets.

11. A railway vehicle as claimed in claim 10 when appendant to claim 3, wherein the brackets associated with the carrier plate of the or each brake mechanism are attached to a respective side member.

12. A railway vehicle as claimed in any one of claims 1 to 11, wherein the or each first brake pad and the or each second brake pad is aligned with the load-bearing wheels at one side of the vehicle.

13. A railway vehicle as claimed in any one of claims 1 to 11, wherein the or each first brake pad and the or each second brake pad is outwardly off-set with respect to the load-bearing wheels at one side of the vehicle.

14. A railway vehicle as claimed in any one of claims 1 to 11, wherein the or each first brake pad is aligned with the load-bearing wheels at one side of the vehicle, and the or each second brake pad is outwardly off-set with respect to the load-bearing wheels at one side of the vehicle.

15. A railway vehicle as claimed in claim 3 or in any one of claims 4 to 14 when appendantto claim 3, wherein the bridge is provided with a bridge support shaft at each end thereof, the bridge support shafts being mounted in apertures in the side members.

16. A railway vehicle as claimed in claim 15, wherein said apertures in the side members are elongate in the vertical direction, and wherein each side member is provided with a respective slide plate, each slide plate being mounted in a vertical slideway formed in the associated side member, each slide plate being engageable with the end portion of the adjacent bridge support shaft, and each slide plate being operatively associated with the piston(s) of the piston-and-cylinder unit(s) associated with that side member.

17. A railway vehicle as claimed in claim 16 when appendantto claim 7, wherein each slide plate is engageable with the end plate(s) of the piston rod(s) of the piston-and-cylinder unit(s) associated with that side member.

18. A railway vehicle substantially as hereinbefore described with reference to, and as illustrated by, Figures 1 to 3, Figure 4, Figure 5 or Figure 6 of the accompanying drawings.

19. A railway vehicle having a frame provided at each side with load-bearing wheels, the frame being constituted by a pair of side members and a bridge joining the two side members, the side members supporting the load-bearing wheels, and a brake mechanism associated with each of the side members, each brake mechanism having a hydraulic piston-and-cylinder unit whose cylinder is fixed to the frame, a respective brake pad being associated with the piston of each piston-and-cylinder unit for reciprocal movement therewith, respective spring means being provided for biasing each brake pad into contact with an upper surface of a respective rail, each spring means acting between the associated brake pad and a respective abutment member fixed relative to the frame whereby, when the hydraulic pressure in the piston-and-cylinder units is released, the spring means force the brake pads down into contact with said upper surfaces of the rails.