GB2188383A - Friction braking apparatus - Google Patents

Abstract

A wheel and brake assembly for a vehicle comprises a wheel carrier (6, 7, 8A, 8B) pivotally mounted on chassis member (11) and having bearings (4, 5) mounting a rigid axle (3), a pair of wheels (1, 2) mounted in common on the rigid axle (3), a brake disc (13) attached to the axle (3) between the wheels (1, 2), friction means (15, 16, 19, 20) mounted on the wheel carrier, and friction surface means (21) arranged to be pressed controllably by the friction means (15, 16, 19, 20) against at least one face of the disc (13). Brake pads are provided in the chassis for engaging the track if suspension assemblies (not shown) should fail. <IMAGE>

Description

SPECIFICATION Friction braking apparatus The present invention relates to friction braking apparatus for the wheels of a vehicle and especially a railway vehicle, although the invention may also be used in vehicles of othertypes.

Conventional wheel-engaging brakes on rail vehicles have brake shoes which are brought into contact with the running surface of the flanged wheels and pressed against them to exert a frictional force for slowing down the vehicle. Such brakes have a number of disadvantages. For example, the brake shoe material has to contend with contamination by gritorgrease picked up bythewheel from the rail and is subjected to higher rates of wear because of that contamination and also because of the roughness ofthe running surface produced by the grit being embedded into it by the rail. This difficulty may be aggravated for a mine railway vehicle where the environment is more likely to include broken rocks.Another problem which can arise is that the wheel may skid on the rail and haveaflatportion worn on the running surface, and becausethe running surface is no longer round it causes the braking to be irregular and increases the likelihood of skidding and further uneven wear ofthe running surface.

It is an object of the present invention to provide an improved brakeforavehicleandespeciallya mine railway vehicle.

According to the present invention, there is provided a braked wheel arrangement for a vehicle, including a pair of wheels on a common rigid axle, carried on bearings on a wheel carrier, in which a brake disc is attached to the axle between the wheels and friction means is mounted on the wheel carrier capable of controllably pressing friction surface means against at least one face of the disc.

The friction means may include a caliper with two friction pads or sets of friction pads, which respectively engage the faces of the disc. There may be more than one brake disc on the axle and the friction means may be arranged to press friction surface means against one or both faces of each disc.

The disc may have air passages through itto assist its cooling and maycomprisetwo discs ora discand an annulusjoined by radial extending bridge pieces.

The wheel carrier may be a suspension member resiliently mounted on a chassis or bogie ofthe vehicle. The mounting of the suspension member may be by pivot with one or more spring arrangements operating in tension or compression.

The wheel carrier may be attached to leaf springs with or without a stay to resist the torque produced by the application ofthe brake.

In a particular application ofthe invention, the vehicle is a railway vehicle, especially a mine railway vehicle, and the wheels may be flanged for running on rails. The wheel carriers may be attached to a bogie on the vehicle, to which a second wheel carrier is also attached in a symmetrical arrangement; either or both of the axles of the wheel arrangements may be braked.

In orderthatthe invention may be fully understood, and readily carried into effect, it will now be described with reference to a specific embodiment shown in the accompanying drawings, ofwhich: Figure 1 is the internal side view of the embodiment; and: Figure2isa plan viewofthe embodiment.

The embodiment shown in the drawings is attached to a bogie which is provided with a second similar arrangement, arranged symmetrically on the bogie. For convenience, only the one arrangement is shown in full, but in the figures the lines A-A and B-B indicate the centres of the drawings, the left-hand sides of which have been omitted from the drawings.

Referring now to the drawings, wheels 1 and 2 are radially attached to a common rigid axle, 3. The axle 3 is borne on bearings 4and 5 in pivoted links 6 and 7, respectively. The links 6 and 7 are rigidly joined by bars, 8A and 8B, and are supported on pivot bearings 9 and 10on chassis member 11 of the bogie.

Suspension assemblies each comprising a pneumatic or hydraulic cylinder and which may also incorporate springs, and of which only two are shown in figure 1, having the reference 12, extend between the chassis member 11 and the iinks 6 and 7. Centrally located on the axle, 3, and fixed to it is a ventilated brake disc, 13, having central passages, 14, through itto assist in the cooling ofthe brake disc. Levers, 15 and 16, are pivoted on pivots 17 and 18, respectively, which extend between the bars 8A and 8B andform abrakecaliper.Atoneend,the levers 15 and 16 carry pressure pads 19 and 20, respectively, with friction material facings, 21. The other ends of the levers 15 and 16, are joined to the ends of a pneumatic or hydraulic cylinder, 22.When the brakes areto be applied, pneumaticor hydraulic pressure is applied to the cylinder, 22, which pushes its ends apart, thereby rotating the levers 15 and 16 about their pivots and pressing the friction material facings, 21, against the outer surfaces of the disc, 13, sothatthefriction is effective to brake the wheels 1 and 2.

To assist in the absorption of shocks, the bearings 4 and 5, in which the axle, 3, runs, are attached to the links 6 and 7, through the intermediary of bonded rubber shock absorbing blocks, 23 and 24. The suspension assemblies 12may provide additional springing. The drawing also shows pipes, 25, for conveying grease or oil from the lubrication nipples, 26, to the bearings, and 5, and the pivots,9 and 10.

Afurther pipe, 27, runs from another of the nipples, 26, to a bearing, 28, about which the bogie chassis, 1 can turn on the body of the truck or coach to which it is attached.

To the under-side of the chassis,11, are attached copper brake pads, 29, shown in figure 1, which are placed so as to rub on the rails if the pressure in the suspension assemblies, 12, fails and allows the bogie to subside. The assemblies 12 may be connected to a pressure reservoirforthe brake system so that ifthe pressure in the reservoirfalls unduly the bogie is iowered to bring the brake pads 29 against the rails.

Various modifications can be made to the embodimentofthe invention shown in the drawings.

For example, provided thatthe axle, 3, carries thrust bearings, the braking pressure could applied to one side only of the disc, 13, for example, by attaching the braking friction facing directly to a pneumatic or hydraulic cylinder mounted on either one of the links, 6 and 7, orthe bars, 8A and 8B. If two discs are provided on the axle friction facings could be arranged to press in opposite directions on single faces only ofthe discs; in this case there would be no need for thrust bearings to withstand the braking forces. The invention could also be used in a vehicle provided with pneumatic-tyred wheels for running on roads or similar surfaces, although it is particularly advantageous for use on railway vehicles. A mechanical linkage could be substituted for the brake pressure cylinder 22 to press the friction facings 21 against the disc faces.

Claims (18)

1. Awheel and brake assembly for a vehicle, the assembly comprising: a wheel carrier having bearings mounting a rigid axle, a pair of wheels mounted in common on the rigid axle, a brake disc attached to the axle between the wheels, friction means mounted on the wheel carrier, and friction surface means arranged to be pressed controllably bythefriction means against at least one face of the disc.

2. An assembly as claimed in claim 1,wherein the friction means includes a caliper with two friction pads, each pad being arranged to engage a respective face of the brake disc.

3. An assembly as claimed in claim 1, wherein the friction means includes a caliper with two sets of friction pads, each set of pads being arranged to engage a respective face ofthe brake disc.

4. An assembly as claimed in any preceding claim, wherein more than one brake disc is attached to the axle and the friction means is arranged to press the friction surface means against one or both faces of each disc.

5. An assembly as claimed in any preceding claim, wherein the or each brake disc has air passages through itto assist cooling ofthe brake disc(s).

6. An assembly as claimed in any preceding claim, wherein the or each brake disc is constituted by two disc-shaped members joined by radiaily-extending bridge pieces.

7. An assembly as claimed in any one of claims 1 to 5, wherein the or each brake disc is constituted by a disc-shaped memberjoined to an annulus by radially-extending bridge pieces.

8. An assembly as claimed in any preceding claim, wherein the wheels are flanged for running on rails.

9. Awheel and brake assembly for a vehicle, the assembly being substantially as herein described with reference to, and as illustrated by, the accompanying drawings.

10. Avehiclechassisorbogieincluding an assembly as claimed in any one of claims 1 to 8, wherein the wheel carrier is a suspension member resiliently mounted on the chassis or bogie.

11. A chassis or bogie as claimed in claim 10, wherein the suspension member is mounted by a pivot and the mounting includes one or more spring arrangements operating, in use, intension.

12. A chassis or bogie as claimed in claim 10, wherein the suspension member is mounted buy a pivot and the mounting includes one or more spring arrangements operating, in use, in compression.

13. A chassis or bogie as claimed in claim 10, wherein the wheel carrier is attached to leaf springs.

14. Achassis or bogie as claimed in claim 13, whereinastayisprovidedto resistthetorque produced by the application of the brake.

15. Avehicle including a wheel and brake assembly as claimed in any one of claims 1 to 9, ora chassis or bogie as claimed in any one of claims 8to 13.

16. Avehicleasclaimed inclaim 15when dependent on claim 8, wherein the vehicle is a mine railway vehicle.

17. Avehicle as claimed in claim 15 or claim 16, wherein the wheel carrier is attached to a bogie on the vehicle to which a second wheel carrier, axle and wheels are attached in a symmetrical arrangement of the wheel carriers.

18. Avehicleasclaimedinclaim 17, wherein the axle of each wheel carrier is arranged to be braked.