[0002] Well-established techniques are in widespread use for the construction of rail vehicles and in the arrangement of braking systems for rail vehicles. Typically a rail vehicle is braked by using a compressed air source which is reticulated to each of a plurality of rail vehicles, which make up a train, via a pipeline and which is used at each wheel which is to be braked to energise an actuator. Although this type of braking system is acceptable it requires a substantial amount of hardware which is expensive and which calls for regular maintenance. An unrelated factor is that certain of the components in the braking system are made from valuable metals and, particularly in poorer countries or remote areas, are the target of theft. This leads automatically to a non-operational system.

[0003] Ideally when a rail vehicle is braked the braking force should be regulated so that the wheels do not become locked and skid over the rails. When this happens rapid wheel wear occurs which soon gives rise to costly maintenance requirements. If all the vehicles in a train were loaded to the same extent then it would be possible to regulate the braking force to prevent wheel skidding. The vehicles within a train are however not usually uniformly loaded and, unless a regulating mechanism is used, all the vehicles are subjected to the same braking force which renders the lighter loaded vehicles more prone to wheel locking.

[0004] A need therefore exists for a braking system which is relatively inexpensive and which is not of a complex construction, which is relatively easy to use and which can automatically adjust the braking force to each wheelset on a wagon and within a train.

SUMMARY OF THE INVENTION [0005] The invention provides in the first instance, an assembly for use with a wheelset which includes an axle box and at least one actuator which is engaged with the axle box and which, when actuated, causes relative movement of the axle box away from a structure against which the actuator reacts.

INT1099/MAJR/jes 2 [0006] Preferably the assembly includes two actuators. A first actuator may be positioned on one side of the axle box and a second actuator may be positioned on an opposing side of the axle box.

[0007] Each actuator may be in the form of a jack or a ram. Preferably however each actuator is in the nature of a bellows which may be operated by means of a pressurised fluid for example a hydraulic liquid e. g. water.

[0008] The assembly may include at least one suspension component on the axle box.

[0009] The axle box preferably has a centrally positioned axle mounting formation and, in a preferred form of the invention, a first suspension component is positioned on one side of the axle mounting formation and a second suspension component is positioned on an opposing side of the axle mounting formation.

[0010] Each suspension component may be positioned on a respective inclined surface adjacent the axle mounting formation.

[0011] Each suspension component may include a plurality of chevrons made for example from a resiliently deformable material such as rubber, an elastomeric material, or the like.

[0012] At least one braking element may be mounted for movement relatively to the axle box.

The braking element may include a brake block or shoe or similar component and means for causing movement thereof with a braking action.

[0013] The invention further extends to a wheelset which includes an axle, a first wheel at one end of the axle, a second wheel at an opposed end of the axle, a first assembly of the aforementioned kind, at one end of the axle and a second assembly of the aforementioned kind at an opposed end of the axle.

[0014] A compressed fluid pipeline may extend the length of the structure. Compressed fluid from the pipeline may be used to operate each of the actuators.

[0015] The invention also provides a method of braking a vehicle which includes a structure supported on a plurality of wheels, the method including the steps of elevating the structure relatively to at least one of the wheels thereby to move at least one braking member out of engagement with a braking surface which is associated with a respective wheel and, when braking is required, of allowing the structure to move downwardly relatively to the at least one

I NT1099/MAJ R/jes 3 wheel so that the braking member is moved into frictional engagement with the braking surface thereby to exert a braking action on the at least one wheel.

[0016] The structure may be any structure which is supported on the wheels and generally will include at least a chassis and a body, housing or other containment arrangement which may be associated with the chassis.

[0017] The wheels of the vehicle may be rail wheels which are engaged with rail tracks.

[0018] The structure may be moved upwardly relatively to all of the wheels. This may be achieved in any appropriate way but preferably use is made of a hydraulic device or devices to elevate the structure. Each device may be in the nature of a hydraulic jack or ram.

[0019] The braking member may be a brake shoe or similar device.

[0020] The braking surface may be any suitable surface which is associated with a wheel but preferably is a peripheral surface of a wheel.

[0021] The structure, when the hydraulic device is de-energised, moves downwardly, under gravity action.

[0022] The invention also provides a braking system for a vehicle which has a structure which is supported on a plurality of wheels, the braking system including at least one hydraulic ram for elevating the structure relatively to at least one of the wheels thereby to move at least one braking member out of engagement with a braking surface which is associated with a respective wheel and a pressure release mechanism which is operable in a controlled manner for allowing the structure to move downwardly relatively to the at least one wheel, when braking is required, so that the braking member is moved into frictional engagement with the braking surface thereby to exert a braking action on the at least one wheel.

[0023] The braking member is preferably a brake shoe or similar component which is arranged so that it is movable, when the structure moves downwardly, into frictional engagement with a peripheral surface of the wheel. Conversely, when the structure is moved upwardly by energising the hydraulic device, the brake shoe is moved out of frictional engagement with the peripheral surface of the wheel.

[0024] The braking system of the invention can be used with a variety of different vehicles and is well suited for the braking of a rail vehicle. In particular the braking system can be used

effectively with a rail vehicle, of relatively simplified design, which includes a chassis which is mounted to at least two wheel pairs using focalising techniques. The invention is intended to cover this particular combination.

BRIEF DESCRIPTION OF THE DRAWINGS [0025] The invention is further described by way of examples with reference to the accompanying drawings in which: Figure 1 illustrates a wheelset according to the invention; Figure 2 shows the wheelset of Figure 1, from the side, in combination with braking equipment; Figure 3 shows the arrangement of Figure 2 from the front; Figure 4 schematically illustrates the use of compressed air for operating hydraulic braking equipment included in the wheelset of the invention; Figure 5 is a simplified perspective view of a chassis and wheel pairs of a rail vehicle which includes a braking system according to the invention; Figure 6 is a plan view of the vehicle shown in Figure 5; and Figure 7 is a side view of one of the wheels and associated structure shown in Figure 5.

DESCRIPTION OF PREFERRED EMBODIMENTS [0026] Figure 1 of the accompanying drawings illustrates a wheelset 10 according to the invention which includes an axle 12 which is of conventional construction and wheels 14 and 16 which are also of conventional construction. The wheels are mounted to respective opposed ends of the axle.

[0027] Suspension and braking assemblies 18 and 20 respectively are mounted to respective ends of the axle 12. The assemblies are for all practical purposes identical and only the construction of the assembly 20 is described hereinafter.

[0028] The assembly 20 includes an axle box 24 which is formed with a centrally positioned axle mounting formation 26 to which the respective end of the axle 12 is engaged.

[0029] The axle box, on opposed sides of the formation 26, has downwardly sloping inclined surfaces 30 and 32 respectively. A plurality of chevrons 34, which are made from rubber or any equivalent elastomeric or similar material of an appropriate hardness, are mounted to the inclined surfaces. The chevrons, viewed in plan, are inclined slightly relatively to the direction in which the wheelset travels when on rails. This technique, which is known in the art, is referred to as"focalising". Without being exhaustive on the subject focalising allows the wheelsets,

INT1099/MAJR/jes 5 including the wheelset 10, on a rail vehicle (not shown) to move relatively to one another in a controlled and stable manner so that the wheelset exerts a self-steering action when it travels on curved rail tracks.

[0030] Upper surfaces of the chevrons 34 abut reaction plates 40 on opposed sides of the axle 12. A support member 42 is secured to the reaction plates and extends over the axle 12 between the reaction plates.

[0031] Two stainless steel bellows 44 and 46 respectively are mounted to extensions of the reaction plates 40 and extend upwardly. Each bellows is normally enclosed in a telescopic arrangement 48 which allows unimpeded movement of the bellows but, at the same time, protects the bellows against damage by foreign objects.

[0032] According to requirement the assemblies 18 and 20 can be prefabricated and supplied to a manufacturer of wheelsets. Altematively the assemblies can be secured to a wheels, substantially in the manner shown in Figure 1, and the resulting complete wheelset arrangement, again substantially as shown in Figure 1, can then be supplied to a manufacturer of rail vehicles.

[0033] The constructions in Figures 1 and 2 are not identical. In the former instance braking gear has been omitted while in the latter case the braking equipment is included.

[0034] Figure 2 shows th3 wheelset 10 from the side. A crosspiece 50, which is mounted to the axle box 24, has bell cranks 52 and 54 respectively pivotally attached to its opposed ends.

Each bell crank is movable by means of a respective pushrod 56 which extends upwardly. An upper end of the pushrod projects through a hole 58 in the support member 42.

[0035] A portion of the structure associated with the bell crank 54 has been cut away to show that a respective brake block 62 is attached to each bell crank. The brake block is positioned so that, when the respective pushrod moves downwardly, the bell crank is actuated to move the brake block with a braking action into engagement with an opposing peripheral surface of the wheel 16.

[0036] Figures 2 and 3 illustrate structure 70 which forms part of a chassis of a rail vehicle which is supported by the wheelset 10 and similar wheelsets, not shown.

[0037] Figure 4 illustrates schematically and in dotted outline the structure 70. It is assumed, merely for illustrative purposes, that the rail vehicle is supported on two wheelsets which are

INT1099/MAJR/jes 6 illustrated only schematically and which are designated 10A and 10B respectively. The respective bellows 44 and 46 associated with each assembly 18 and 20 are also shown in a schematic form. The various bellows are connected by hydraulic lines 78 to a hydraulic cylinder 80. A piston 82, which is engaged with the cylinder, has a pushrod 84 which is connected to a relatively large area piston 86 which is engaged with an air cylinder 90. The air cylinder is supplied with compressed air via a pipeline 92 which traverses the length of the structure 70 and which has conventional connectors 94 and 96 at opposed ends. These connectors enable the line 92 to be connected, in a known manner, with similar compressed airlines on other vehicles, not shown. It is pointed out that this aspect of the invention is known in the art and is therefore not described in detail.

[0038] When the bellows 44 and 46 are not internally pressurised the mass of the structure 70 and any load which is carried by it is such that the structure settles downwardly, under the action of gravity. The various pushrods 56 have flanges 56A which are then brought into contact with lower surfaces of the structure 70. The pushrods are thereby moved downwardly causing the bell cranks to rotate about the respective pivot mounting points. The various brake blocks 62 are thereby urged into braking contact with the peripheral surfaces of the wheels in the various wheelsets.

[0039] If the pipeline 92 is pressurised then the air cylinder 90 is actuated and, in so doing, the hydraulic cylinder 80 is pressurised. Each bellows 44,46 is pressurised by the hydraulic fluid which flows through the lines 78 and the bellows are extended. The bellows move upwardly and the structure 70 is elevated relatively to the various axle boxes 24. The pushrods are no longer urged downwardly and the brake blocks 62 can move out of braking engagement with the various wheels.

[0040] At any time if the rail vehicle, or the train of which the rail vehicle forms part, is to be braked, the air pressure in the line 92 is reduced in a controlled manner. Under the action of gravity the structure 70 moves downwardly and the various pushrods are moved with a force which directly corresponds to the mass which is transferred to the wheelsets by the structure 70.

Consequently the braking forces which are exerted by the brake blocks 62 are proportional to the respective weights borne by the wheelsets. This is a highly desirable feature for it means that heavier vehicles have greater braking forces applied to them while the braking forces which are applied to lighter vehicles are correspondingly reduced.

[0041] It is apparent that by prefabricating assemblies 20 of the kind shown in Figure 1, as self-contained units which embody braking and suspension arrangements, it is possible to

INT1099/MAJR/jes 7 supply a wheels, of the kind shown in Figure 1, which can be used with any suitable type of structure 70. In other words the structure 70 which, for example, may be in the nature of a container, rigidified or reinforced where appropriate, can be engaged with two or more wheelsets with each wheelset being of the type shown in Figure 1. This approach allows the container to be constructed separately from the wheelsets. If desired it is possible to design the container in such a way that it can be engaged in a detachable manner with the wheelsets. This approach differs substantially from prior art techniques which, generally, call for a rail vehicle to have an integral or composite type construction.

[0042] Although the various bellows 44 and 46 are hydraulically actuated the arrangement shown in Figure 4 allows the hydraulic components to be pressurised by means of compressed air. This means that it is possible for a rail vehicle which makes use of the principles of the present invention to be coupled to rail vehicles which are of a different design and which are constructed to be braked by compressed air techniques alone. Thus it is not necessary, when making up a train, to ensure that all of the vehicles in the train are of the same type for vehicles which are braked by the application of air pressure can be coupled to vehicles which are braked by the application of hydraulic pressure.

[0043] Figures 5 to 7 of the accompanying drawings illustrate a variation of the aforementioned principles.

[0044] Figure 5 shows a chassis 108 of a rail vehicle 110 which is mounted on first and second wheel pairs 112 and 114 respectively, which, in turn, are engaged with tracks 116.

[0045] Any suitable structure can be erected on the chassis and the invention is not limited in this regard. In the arrangement shown in Figure 5 the chassis includes a plurality of mounting formations 118 which are designed to mate directly with complementary mounting formations on a standardised 6m container, not shown, which can be loaded directly onto the chassis.

[0046] Figure 6 illustrates, in plan, the wheel pair 114 and some of the suspension components which are used to transfer load from the chassis 108 to the wheel pair.

[0047] Referring as well to Figure 5 the suspension arrangement includes an axle box 120 which houses suitable bearings which support an axle 122 to which wheels 124 are mounted.

[0048] The axle box 120 has inclined plates 130 on opposed sides thereof and resilient chevrons 132, made for example from a suitable grade of rubber, are fixed to the plates. The chevrons, viewed in plan, are inclined slightly relatively to the direction 134 in which the vehicle

INT1099/MAJR/jes 8 travels on the rails. Use is thus made of the"focalising"technique which has been referred to hereinbefore.

[0049] Figure 7 shows part of the chassis 108 in the region of the wheel pair 114. Upper surfaces of the assemblies of the chevrons 132 abut reaction plates 140 on opposed sides of the axle 122. The reaction plates extend downwardly from a substantial steel plate 142 which, at opposed ends, has flange formations 144 and 146. Low friction material 148 is mounted to outer surfaces of the flange formations. Retaining members 150 which extend downwardly from the chassis partially enclose the plate 142 in a manner which prevents relative movement between the plate and the chassis in the longitudinal direction 134 but which allows limited relative movement of the plate relatively to the chassis in a vertical direction 152.

[0050] Hydraulically operated rams 156 and 158 respectively are mounted adjacent the flange formations 144 and 146 on top of the plate 142 and pistons 160 and 162 of the rams extend upwardly to abut against an undersurface 164 of the chassis. A metallic brake shoe 170, which is made in a known manner from a suitable material such as cast iron, is positioned between the rams above a peripheral surface 172 of the respective wheel 124. The brake shoe, on its upper surface 176, is backed by a metal plate 178 which in turn is backed by a low friction planar sheet 180 of material made for example from polytetrafluoroethylene (PTFE). A metal plate 182 is positioned between the surface 164 and an upper surface of the sheet 180.

[0051] A hydraulic line 190 extends longitudinally the length of the chassis. The line includes suitable connections, not shown, to supply hydraulic fluid to the rams 156 and 158. The line terminates at each of its ends in a respective snap-on coupling 192. Only one such coupling is visible in the drawing. A second hydraulic line 194 also extends the length of the chassis and terminates in similar snap-on couplings 192. This line is not connected to the rams 156 and 158.

[0052] Figure 5 shows the vehicle 110 and a portion of a similar adjacent vehicle 110A which is connected to the vehicle 110 in a semi-permanent fashion via an articulated joint 200. The vehicle 110 at its end which is remote from the joint 200 has a coupling member 202 and an end of the vehicle 110A which is remote from the joint has a complementary coupling member, not shown. The coupling members are known in the art and permit a plurality of rail vehicles which are equipped with similar coupling members to be connected one to the other to form an interconnected train.

INT1099/MAJR/jes 9 [0053] When the vehicles have been connected in the manner described the respective snap- on couplings 192 at opposed ends of the various lines 190 are connected one to the other. The couplings 192 on the respective lines 194 are not connected to one another.

[0054] Figure 7 illustrates somewhat symbolically a hydraulic pump 206 which is located at any suitable position on the train, for example at a locomotive. The appropriate hydraulic line 190 is connected to an outlet line 208 from the pump.

[0055] A reservoir or dump tank 210 is connected via a pressure regulator 212 to the line 208.

A line 214 is used to supply fluid from the tank to the pump.

[0056] It is evident from an examination of Figure 7 that if the rams 156 and 158 are not actuated the full weight of the chassis and the structure on the chassis is transferred via the components 182,180 and 178 to the brake shoe 170. The brake shoe is thereby urged into frictional engagement with the periphery 172 of the wheel and consequently the wheel is locked in position and cannot rotate. Maximum braking force is therefore exerted on the wheel with the magnitude of the braking force being determined by the coefficient of friction between the respective mating surfaces and by the mass of the chassis and the structure on the chassis.

[0057] Air which may inadvertently enter the hydraulic system is automatically vented to atmosphere via a bleed valve 220 of known construction.

[0058] If the brake is to be released then the pump 206 is actuated and pressurised hydraulic fluid is delivered by the line 190 to the various rams 156 and 158 at each of the wheels on all of the vehicles in the train. The rams extend and, in each case, the chassis is elevated relatively to the plate 142 i. e. relatively to the respective wheel 124. Each brake shoe 170 is therefore lifted out of engagement with the respective peripheral surface 172 of the wheel.

[0059] During this brake release phase the regulator 212 is closed. If the brakes are to be applied then the pump 206 is stopped and the regulator 212 is opened in a controlled manner.

Hydraulic fluid in the lines 190 flows to the dump tank 210 in a regulated manner and, in so doing, the various rams 156 and 158 are allowed to retract moving, in each case, under gravity action with the amount of force which is exerted being dependent on the mass on the chassis.

As the chassis settles downwardly the corresponding brake shoe 170 is moved into frictional engagement with the peripheral surface 172 of the respective wheel and, in so doing, a braking force is exerted on the wheel which is dependent on the mass carried by the chassis.

INT1099/MAJR/jes 10 [0060] The hydraulic braking system is considerably less complex than a compressed air braking system and is easier to install and maintain. The respective vehicles in a train are coupled to one another, in the braking sense, simply by interconnecting the snap-on couplings 192 at respective ends of the lines 190. As the braking force is gravity-dependent the braking force is automatically increased for heavily loaded vehicles and decreased, in a pro rata manner, for vehicles which are lightly loaded. The various rams 156,158 are effectively serially connected and if one ram fails the braking system will automatically be actuated. It is however possible to bypass the faulty ram once the train has been brought to a halt. The line 190 associated with the faulty ram is disconnected from the remainder of the hydraulic system which runs the length of the train and the respective line 194, which is parallel to the line 190 in question, is connected to the hydraulic circuit so that pressurised hydraulic fluid remains available for the length of the train.

[0061] The brake shoe 170 is constrained against moving in the rotational direction of the wheel 124 by restricting formations 222 at extremities of the plate 178. On the other hand the brake shoes can move in the vertical direction and, moreover, are capable of moving together with the wheel 124 when it moves with a yawing action due to the low frication sheet 180 which is positioned between the plates 178 and 182. Thus, referring again to Figure 6, if there is a tendency for the axle 122 to move with yawing motion as is indicated by means of a double- headed arrow 230 the brake shoes can move in unison with the wheel pair and allow for this type of relative movement.

[0062] If the coefficient of friction between the brake shoe 170 and the wheel is more or less the same as the coefficient of friction between the wheel and the rail then the braking force between the brake shoe and the wheel is less than the braking force between the wheel and the rail. Consequently the likelihood that the wheel will not rotate and will be locked and then slide over the rail is reduced.