AU2019200423A1 - Rail vehicle braking system - Google Patents

Abstract

This invention relates to a bogie for a rail vehicle. The bogie comprises a chassis for mounting a pair of rail engaging rail wheels. A sub-chassis is mounted to the chassis for movement between raised and lowered positions. A hydraulic dump actuator is disposed between the chassis and the sub-chassis and configured to selectively hold the sub-chassis in the raised position against a weight force, when supplied with pressurised hydraulic fluid. At least one brake unit is mounted to the sub-chassis. The brake unit comprises a brake calliper assembly for at least partially receiving a head of the rail when the sub chassis is moved into the lowered position, and a bias means for biasing the brake unit toward an applied configuration in which the brake calliper assembly clamps the sides of the head of the rail in braking engagement. A hydraulic brake release actuator is configured to selectively hold the brake unit in a release configuration against an application force imposed by the bias means, thereby to allow rail insertion into the calliper assembly. The dump actuator and the brake release actuator are configured for operative connection to a brake activation controller for selectively activating bogie braking by discharging hydraulic fluid from the hydraulic dump actuator and hydraulic brake release actuator to dump the sub-chassis from the raised position to the lowered position, and thereby to allow the brake unit to transition from the release configuration to the applied configuration. Figure 2 Figure 2

Description

Rail Vehicle Braking System

Field of the Invention [0001] The invention relates to braking systems for rail vehicles and carriages running on rails and more particularly to emergency braking systems. The invention has been developed for use on inclined railways such as mine access railways. However, the system of the invention may also be applied to other rail applications.

Background to the Invention [0002] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

[0003] Rail carriages and vehicles are typically supported by a chassis or framework carrying wheel sets, which run on the rail track and are known as “bogies” or “trucks”. Typically a bogie is attached at each end of a rail carriage body, and mounted to the carriage on a vertical pivot axis allowing the bogie to yaw with respect to the carriage body. This allows the carriage to negotiate tighter bends in the track and/or allows the carriages to be longer. Another configuration is often used in articulated vehicles, which places bogies under the connection between the carriages or wagons.

[0004] In mining operations, and particularly underground mining operations, railways are often used as a means for transporting personnel and material into and from the mine. It is usual for such railways to traverse steep inclines where wheel traction may present an issue, particularly where contaminates such as dust, water and oil may be present on the tracks. Accordingly rather than use a locomotive to tow or push the rail vehicles, many mine railways employ a drum winder positioned at the upper end of the track attached to the carriages by a cable to pull the carriages up the gradient. In normal operation, the drum winder and cable are also used to control the rate of descent of the carriages against the pull of gravity. Such rail systems, which may equally be used in above ground and non-mining related applications, are known as cable railways, incline plane railways or inclinators. A variation of the cable railway is the funicular in which a cable is attached between counter-balancing carriages and looped around top mounted pulley.

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-2[0005] In normal operations, control of the carriages including braking may be performed adequately by balancing the drum winder rate against the pull of the rail vehicle. However in case of a cable or drum winder failure, the carriages require an alternative or emergency braking system independent of the cable.

[0006] One alternative braking system provides a skid type dump brake whereby a braking contact skid is held in an elevated position above the rail and upon activation, in an emergency, is lowered onto the head of the rail surface to provide a frictional braking force with the rail. However the maximum braking force which may be generated is limited by the mass of the carriage pressing down on the skid and the co-efficient of friction between the head of the rail and pad. Thus the braking force provided by skid type dump brake reduces with increasing track steepness and or track contamination.

[0007] Another system commonly used in mine rail cars is described in WO 83/00669 and known as the Franlane brake. In this system, the contact skid is replaced with a rolling wheel having a rail capturing notch for receiving the rail when the wheel is lowered on to the track. The notch is provided with tapering lateral faced flanges which mechanically engage the head of the rail and provide a gripping, rolling contact for applying a braking force to the rail and decelerate the carriage.

[0008] While Franlane brakes have been shown to provide a significant improvement over skid dump brakes, the practical implementation of the Franlane system has raised concerns about its operational consistency. That is to say, it has been shown that the Franlane system may be intolerant of rail wear, and gauge and track trueness being outside relatively tight operational specification envelope. For instance, the maximum braking force which can be generated by Franlane systems remains highly dependent on the normal force (weight force) acting downwardly on the brake unit. Asymmetrical undulations across the rail tracks detrimentally affect the normal force at each brake meaning reduced total braking force. Maintaining the rail tracks to required specification, particularly in underground systems may prove costly and challenging. Furthermore, being an emergency system, any shortcomings in maintenance may not become apparent until the system is activated in an emergency.

[0009] An alternative configuration described in WO 83/00669 replaces the tapered notch on the wheel with a thrust ring arrangement which clamps the rail against a flange on the braking wheel. Brake pads are used to then slow the wheel. This configuration appears overly complex and is rarely used.

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-3[0010] A Franlane system is also described in Australian patent Application No 2015264812 which teaches a unitary central frame member whilst retaining the Franlane brake units.

[0011] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

Summary of the Invention [0012] In a first aspect, the invention provides a bogie for a rail vehicle comprising:

a chassis for mounting a pair of rail engaging rail wheels;

a sub-chassis mounted to the chassis and movable with respect to the chassis between a raised position and a lowered position, the sub-chassis including a mounting formation for supporting a body of the rail vehicle;

a hydraulic dump actuator disposed between the chassis and the sub-chassis and configured to selectively hold the sub-chassis in the raised position against a weight force, when supplied with pressurised hydraulic fluid;

at least one brake unit mounted to the sub-chassis, the brake unit comprising:

a brake calliper assembly for at least partially receiving a head of the rail when the sub chassis is moved into the lowered position;

a bias means for biasing the brake unit toward an applied configuration wherein the brake calliper assembly clamps the sides of the head of the rail in braking engagement;

a hydraulic brake release actuator configured to selectively hold said brake unit in a release configuration against an application force imposed by said bias means, when supplied with pressurised hydraulic fluid, and thereby to allow rail insertion into the calliper assembly; and wherein the dump actuator and the brake release actuator are configured for operative connection to a brake activation controller for selectively activating bogie braking by discharging hydraulic fluid from the hydraulic dump actuator and hydraulic brake release actuator thereby to dump the sub-chassis from the raised position to the lowered position, and allow the brake unit to transition from the release configuration to the applied configuration.

[0013] Preferably, the brake control is operatively configured to dump the sub-chassis into the lowered position prior to the brake calliper assembly clamping the sides of the head of the rail in braking engagement.

[0014] Preferably, the brake control is operatively configured to dump the sub-chassis into the lowered position prior to the brake moving to the applied configuration.

2019200423 22 Jan 2019 [0015] Preferably, the dump actuator includes a dump release valve for discharging hydraulic fluid from the dump actuator, said dump release valve operatively connected to the brake activation controller.

[0016] Preferably, the brake release actuator includes a brake release valve for discharging hydraulic fluid from the brake release actuator, said brake release valve operatively connected to the brake activation controller.

[0017] Preferably, the brake activation controller activates bogie braking such that the subchassis moves into the lowered position before the brake calliper moves into the applied configuration.

[0018] Preferably, the brake activation controller activates the dump release valve and the brake release valve sequentially, more preferably the dump release valve is activated in advance of the brake release valve.

[0019] Alternatively the brake activation controller activates the dump release valve and the brake release valve simultaneously.

[0020] Preferably, the sub-chassis dump time is substantially less than the brake unit application time.

[0021] Preferably, the sub-chassis dump time is less than 1 second and the brake unit application time is between 1 and 2 seconds.

[0022] Preferably, the sub-chassis dump time and the brake unit application time are independently adjustable.

[0023] Preferably, the dump actuator is connected to a dump hydraulic circuit for supplying pressurised hydraulic fluid to the dump actuator.

[0024] Preferably, the brake release actuator is connected to a brake release hydraulic circuit for supplying pressurised hydraulic fluid to the brake release actuator.

[0025] Preferably, the brake calliper includes a pair of spaced, laterally opposed brake pads for braking engagement with the sides of the head of the rail.

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- 5[0026] Preferably, the pair of laterally opposed brake pads are held at a closer spacing when the calliper is in the applied configuration than when the calliper is in the release configuration.

[0027] Preferably, the brake calliper includes a third brake pad within said calliper and disposed for engaging the superior surface of the head of the rail.

[0028] Preferably, the brake calliper is a spring applied hydraulic release brake.

[0029] Preferably, the bogie includes at least two pairs of rail engaging wheels, each pair rotatably mounted to the chassis on respective axle members extending transversely across the bogie and defining the respective parallel wheel axes.

[0030] Preferably, the chassis includes a pair of longitudinally disposed side members spaced on either side of the bogie centreline and connecting the axle members.

[0031] Preferably, each side member includes a central recess to accommodate the subchassis.

[0032] Preferably, the mounting formation includes a pivot for pivotable mounting of the bogie to the body of the vehicle.

[0033] In another aspect the invention provides a rail vehicle including a rail bogie as defined above.

[0034] In another aspect the invention provides a bogie for a rail vehicle comprising:

a chassis for mounting respective pairs of rail engaging wheels;

a sub-chassis mounted to the chassis and movable with respect to the chassis between a raised position and a lowered position, the sub-chassis including a mounting formation for supporting a body of the rail vehicle;

a dump release means disposed between the chassis and the sub-chassis and configured to selectively hold the sub-chassis in the raised position;

at least one brake unit mounted to the sub-chassis, the brake unit comprising:

a brake calliper assembly for at least partially receiving a head of the rail when the sub chassis is moved into the lowered position;

a bias means for biasing the brake unit toward an applied configuration wherein the brake calliper assembly grips the sides of the head of the rail in braking engagement;

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-6a brake release means configured to selectively hold said brake unit in a release configuration, against an application force imposed by said bias means to allow rail insertion into the calliper assembly; and wherein wherein the dump means and the brake release means are configured for operative connection to a brake activation controller for selectively activating bogie braking by activating the dump means and brake release means thereby to dump the sub-chassis from the raised position to the lowered position, prior to the brake unit transitioning to the applied configuration. [0035] In one preferred form of the invention the dump release means may include at least one of a mechanical catch, pneumatically or electrically operated dump release mechanism to activate dumping. In other forms the dump release means includes a dump damper which controls the dump rate. The dump damper may include friction operated damping, hydraulically operated damping and/or pneumatically operated damping.

[0036] In another preferred form of the invention the brake release means may include at least one of a mechanical catch, pneumatically or electrically operated brake release mechanism to activate braking. In other forms the brake release means includes a brake application damper which controls the brake application rate. The brake damper may include friction operated damping, hydraulically operated damping and/or pneumatically operated damping.

[0037] In another aspect the invention provides a method of retrofitting a rail bogie for a rail vehicle, said rail vehicle comprising:

a chassis for mounting a pair of rail engaging rail wheels;

a sub-chassis mounted to the chassis and movable with respect to the chassis between a raised position and a lowered position, the sub-chassis including a mounting formation for supporting a body of the rail vehicle;

a hydraulic dump actuator disposed between the chassis and the sub-chassis and configured to selectively hold the sub-chassis in the raised position against a weight force, when supplied with pressurised hydraulic fluid;

at least one lowerable braking wheel mounted to the sub-chassis, the wheel having a rail capturing notch for receiving the rail when the wheel is lowered on to the track;

wherein said method comprises the steps of:

removing the at least one lowerable braking wheel from the sub-chassis: mounting to the sub-chassis a brake unit comprising:

a brake calliper assembly for at least partially receiving a head of the rail

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-7when the sub chassis is moved into the lowered position;

a bias means for biasing the brake unit toward an applied configuration wherein the brake calliper assembly clamps the sides of the head of the rail in braking engagement; and a hydraulic brake release actuator configured to selectively hold said brake unit in a release configuration against an application force imposed by said bias means, when supplied with pressurised hydraulic fluid, and thereby to allow rail insertion into the calliper assembly; and connecting the dump actuator and the brake release actuator to a brake activation controller for selectively activating bogie braking by discharging hydraulic fluid from the hydraulic dump actuator and hydraulic brake release actuator thereby to dump the subchassis from the raised position to the lowered position, and allow the brake unit to transition from the release configuration to the applied configuration.

[0038] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

Brief description of the drawings [0039] The invention will be more clearly understood from the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which: [0040] Figure 1 is perspective view of a rail carriage incorporating a bogie arrangement in accordance with an embodiment of the present invention;

[0041] Figure 2 is a perspective view of a rail bogie including a brake system in accordance with the present invention mounted on one side of the central frame and a Franlane brake system mounted on the opposite side of the frame;

[0042] Figure 3 is a plan view of the bogie shown in Figure 2;

[0043] Figure 4 is a side view of the bogie shown in Figure 2;

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-8[0044] Figures 5A and 5B are side views of the bogie shown in Figure 2 wherein the chassis is illustrated in raised and dumped positions respectively;

[0045] Figure 6 is an exploded perspective view of selected parts of the bogie shown in Figure 2. The Figure displays the bogie chassis and sub-chassis, a brake unit in accordance with the invention and a pair of hydraulic dump cylinders. Select parts, including all but a single rail wheel have been omitted from the figure, to better display the invention;

[0046] Figures 6A and 6B are side views of the bogie shown in Figure 2 wherein the chassis is illustrated in raised and dumped positions respectively;

[0047] Figures 7A and 7B are a perspectives view of a brake unit in accordance with the invention; and [0048] Figures 8A - 8C are end views of a brake unit in accordance with the present invention shown in various positions with respect to a respective rail of the rail track. In Figure 8A, the brake unit is shown in a position corresponding to the raised position, in Figure 8B the brake unit is shown in the release configuration and a position corresponding to the dumped position of the sub-chassis, while in Figure 8C the brake unit is displayed in the applied configuration with the calliper gripping the sides of the head of the rail in braking engagement. In these figures various components of the brake unit have been omitted to better illustrate the brake unit and its interaction with the rail.

Detailed description of a preferred embodiment [0049] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0050] Referring now to the drawings and initially the illustration in Figure 1, a vehicle 1 in the form of an unpowered rail carriage, such as that commonly used in mining applications, is configured for use in conjunction with a typical drum winder (not shown) and cable activated

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-9cable railway. It will be appreciated that while the present invention will be described below in relation to its application for use with such vehicles in mining applications, it may equally be used in other rail vehicles and railway types to provide an emergency braking system. For instance, the invention may be applied to any vehicle or carriage of a powered train having a locomotive, including the locomotive.

[0051] In the embodiment shown in Figure 1, the vehicle 1 is adapted for running on a pair of rails 3 forming a railway track and includes a carriage body 4 that may be configured for transporting various loads including, for example, accommodating personnel, carrying machinery, equipment and material or the like, as required. For instance, the carriage 1 illustrated in Figure 1 includes three separate compartments 5 each configured for transporting personnel. A plurality of carriages may be linked together to form a train.

[0052] The carriage body is mounted on a pair of rail bogies 6. Each rail bogie being pivotally mounted at a respective end of the carriage 1 about respective vertical yaw axes thereby allowing the bogies to independently pivot and follow bends in rail track. In this embodiment each bogie (shown in Figure 2) includes a bogie chassis 7 and at least two pairs of rail wheels 8 rotationally mounted to the bogie chassis on pairs of parallel, spaced wheel axles, for engaging the rail tracks. The rail wheels may be mounted by convention roller bearings or the like to permit free rotation thereby allowing the bogie and carriage to freely roll along the tracks. As is known, each rail wheel includes a circumferential flange on the inboard edge thereby cooperatively holding the rail wheels on respective rails of the track.

[0053] As noted, in normal operations, the 1 motion of the vehicle along the track is controlled by a drum winder and cable 2 attached to the carriage 4. The drum winder not only winds in cable to pull the vehicle up the incline, it also regulates the rate at which cable is payed out against weight force of the vehicle to control vehicle speed on descent. In addition the drum is used to brake and hold the vehicle stationary. However, as noted previously in case of a cable or drum winder failure, the carriage is equipped with an alternative or emergency braking system 10 independent of the cable.

[0054] In an emergency situation, for instance, if a winder cable 2 were to fail, the emergency brake may be manually activated by an operator or passengers. In this regard the vehicle compartments are equipped with emergency brake activation interface allowing a person riding on the carriage to initiate braking. The interface may be in the form of one or

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- 10more of a push button, rope pull, lever, switch or any other activation interface. In some embodiments, similar control interfaces are provided at various locations along the rail way.

[0055] Furthermore, the brake may be activated automatically by a railway control system which is configured to monitor various operational parameters of the railway. In this regard, the railway control system includes various sensors used to monitor the motion of the vehicle to confirm vehicle position and speed. The sensors include sensors mounted to the vehicle body which monitor the relative ground and track speed; sensors for monitoring wheel rotation; and other sensors, such as tilt or derailment sensors, to monitor whether the vehicle is correctly running on the rail tracks. Sensors are also used to monitor drum winder parameters including cable payout speed, motor current draw and cable tension. Furthermore, track mounted sensors may be disposed at track junctions and turnouts and other predetermined positions along the track to monitor the railway. Data from the sensors is analysed by the railway control system to confirm that the rail vehicle and rail system are operating as intended.

[0056] Figures 2, 3 and 4, display respective perspective, plan and side views of an embodiment of a rail bogie 6 having an emergency brake unit 10. The bogie 6 and brake unit 10 are described in detail below however, by way of an initial summary, referring to Figures 5A, in normal operation the emergency brake unit is held out of the way, above the level of the rail tracks, however if and when required, as shown in Figure 5B, the brake unit is lowered into a position where it is able to grip the head of the rail 3 to provide frictional braking.

[0057] In this embodiment the bogie chassis 7, shown separately in the exploded view of Figure 6, is formed of fore and aft axle members 11 extending transversely across the bogie and defining respective parallel wheel axes. Each axle member 11 includes a wheel hub 12 at respective opposite ends for mounting a rail wheel 8. In this regard, it should be noted that select parts of the bogie assembly, including all but a single rail wheel have been omitted from Figure 6, to more clearly show features of the bogie and invention.

[0058] The axle members 11 are connected by longitudinally disposed side members 13 spaced on either side of the bogie centreline. Each side member 13 includes a central recess 14 to accommodate a centrally disposed transverse sub-chassis 15 positioned between the pairs of rail wheels. In this embodiment each side member comprises a lower part 13a and an upper part 13b which in this embodiment are welded together. In other embodiments the chassis and/or sub-chassis each maybe formed of a single unity piece or of multiple parts

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- 11 secured together with bolts thereby allowing disassembly. As will be seen, the recesses 14 are sized to allow the sub-chassis to move upwards and downwards with respect to the chassis between raised and lowered positions.

[0059] The sub-chassis 15 further includes a central mounting formation to allow mounting of the bogie to the underside of the rail vehicle. The formation includes a central pivot pin 16a defining a bogie yaw axis and a circumferential support ring 16b disposed around the pin. The pin facilitates pivotal movement in a plane generally parallel to the underside of the vehicle thereby to allow each bogie to independently move with respect to the other, and the carriage to follow bends in the rail track, while the support ring supporting the weight of the vehicle body.

[0060] Some rail vehicles may include only a single bogie which is rigidly attached to the vehicle body by means of the sub-chassis. That is to say the sub-chassis is incorporated into the vehicle body or body chassis.

[0061] Lateral, peripheral portions of the sub-chassis provide a mounting position for an emergency brake unit 10, between the pairs of rail wheels. As can be seen clearly in Figures 3 and 4, the bogie as illustrated includes an emergency brake unit 10 in accordance with the invention mounted on the near side, and a known Franlane emergency brake unit 10a mounted on the opposite side. This figure is merely for illustrative purposes and in practice preferably, the bogie would be fitted with the same type of brake unit on each side. However, it will be appreciated that this figure illustrates how an embodiment of a new brake unit, as described herein, may be adapted to fit bogies originally intended for use with Franlane brake units. Advantageously this allows retro-fitment of bogies originally made for use with the Franlane system, with a brake unit in accordance with the invention without substantial modification or replacement.

[0062] In order to lift the sub-chassis 15 to the raised position from the lowered position and hold it there, a pair of actuators 18 (see Figure 6) are mounted between the side members 13 and the sub-chassis 15 within each side member recess 14. In this embodiment, the actuators 18 are in the form of hydraulic dump actuators each having a hydraulic dump cylinder connected at respective ends to a respective side member and the sub-chassis. The hydraulic dump cylinders include a cylinder portion 18a for receiving a piston portion 18b and defining a chamber for pressurised hydraulic fluid therebetween. A hydraulic circuit is provided for supplying pressurised hydraulic fluid to the respective chambers thereby extending the piston

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- 12portion 18b from the cylinder potion 18a and lifting the sub-chassis 15 toward the raised position.

[0063] Downward movement of the sub-chassis 15 toward the lowered position is affected by weight force. That is to say, the dump actuators 18 are provided with a dump release valve which may be activated to discharge or “bleed” hydraulic fluid from their respective hydraulic chambers such that the piston portion 18b is forced to retract into the cylinder portion 18a under the weight force of the sub-chassis 15 and the vehicle body 4. This allows the subchassis 15 and the brake units 10 to be “dumped” into engagement with the rails 3 of the track. The time and rate at which the sub-chassis 15 transitions from the raised to lowered position, herein referred to as the (dump rate) “dump time” and “dump rate”, are directly dependant on the rate at which the dump release valve discharges hydraulic fluid from the dump cylinders 18. In this embodiment, the dump release valve is chosen to provide a relatively rapid discharge of hydraulic fluid from the dump actuators and corresponding rapid dump rate such that the dump time it takes the sub-chassis 15 to completely transition from the raised to lowered position within a period of around one second and preferably, less than one second.

[0064] An embodiment of a brake unit 10 in accordance with the invention is shown in Figures 7A and 7B. As noted a brake unit is fixedly mounted to each lateral peripheral portion of the sub-chassis 15. In this embodiment the brake unit 10 is bolted in position.

[0065] Each brake unit employs a brake calliper assembly 20 having a brake calliper 21 and a rail receiving slot 22 for at least partially receiving the head 3a of a rail 3 of the track when the sub-chassis 15 is dumped into the lowered position. In this respect the brake unit 10 is mounted to the sub-chassis 15 such that in the raised position, the rail receiving slot 22 is aligned with and directly above a respective rail, so that on dumping the sub-chassis, the rail is captured in the rail receiving slot 22 of the calliper. To facilitate ease of rail capture in the slot 22, a guide 23 having a tapered guide surface funnels the rail 3 into the slot.

[0066] A dump pad 24 within the slot is disposed to abut the superior surface of the head 3a of the rail to limit the downward movement of the brake units 10 and sub-chassis 15 thereby in effect, defining the lowered position. As previously noted, the bogie 6 is shown in Figures 5A and 5B with the sub-chassis 15 in the raised and lowered positions, respectively. The relative position of the brake unit 10 and calliper assembly 20 with respect to the rail 3 can be seen in the detailed views of Figure 8A (raised position) and 8B (lowered position). It should be noted

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- 13that, in these views, various components of the bogie and brake unit have been omitted for clarity.

[0067] Furthermore, with reference to Figure 8A it can be seen that in the raised position, the brake unit 10 is lifted above the level of the top of the respective rail 3. This allows the brake unit 10 to clear rail bends and turnouts in normal operation without snagging on the rail tracks and ancillary rail infrastructure. Should the vehicle encounter unplanned debris on the side of the track, the bogie 10 is fitted with front and rear deflector guards 50 (see Figure 7) which are shaped and positioned to deflect debris away from an impact with the braking unit and protect against direct impacts on the brake unit.

[0068] In this embodiment the brake unit is a spring applied hydraulic release brake comprising a bias means, in the form of a bias spring 25, for providing an application force biasing the brake unit 10 toward an applied configuration in which the brake calliper assembly grips the sides of the head 3a of the rail 3 in braking engagement. A hydraulically operated brake release actuator 27 is configured to selectively hold the brake unit in a release configuration, against the application force imposed by the bias means. The brake unit is shown in the release configuration in Figure 8B and the applied configuration in Figure 8C.

[0069] The brake release actuator 27 includes a hydraulic cylinder which, when connected to a supply of pressurised hydraulic fluid, acts counter to the application force of bias spring 25 thereby holding the brake in the release position. The hydraulic cylinder includes a cylinder portion for receiving a piston portion and defining a chamber for pressurised hydraulic fluid therebetween. The hydraulic chamber is connected to a hydraulic circuit for delivering pressurised hydraulic fluid to the chamber.

[0070] It will be appreciated that discharging hydraulic fluid from the brake release actuator 27 will allow the bias spring 25 to push the calliper assembly 20 into the applied configuration. In this regard the brake release actuator is provided with a brake release valve for controlled discharge of hydraulic fluid from the hydraulic chamber and for transitioning the brake unit from the release configuration to the applied configuration.

[0071] Referring to Figure 8, in this embodiment, the bias means include two stacks of stackable spring washers 30 evenly spaced around the brake calliper centreline. The spring washers 30 may be stacked in opposite or the same orientation to provide a measure of adjustment of spring travel and spring constant as required. For example, stacking spring

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- 14washers in the same direction may increase the spring constant while stacking in the reverse direction may increase spring travel.

[0072] The brake calliper assembly 20 includes a pair of spaced, laterally opposed brake pads 35 configured for braking engagement with the sides of the head 3a of the rail 3 under the influence of the bias spring 25. As can be seen in Figure 8B, in the release configuration, the pads 35 are held relatively spaced apart by the brake release actuator against the bias spring. Notably, in the release configuration, the lateral spacing between the pads 35 is larger than the width of the head 3a of the rail thereby allowing the calliper to freely capture the rail between the pads 35 when the sub chassis 15 is moved into the lowered position. Advantageously, the lower edge 36 of each pad 35 is tapered to guide the rail into the calliper slot and between the brake pads.

[0073] Referring to Figure 8, the dump pad 24 positioned within the calliper slot and disposed for engaging the superior surface of the head 3a of the rail 3 can clearly be seen. In addition to providing a stop for limiting downward travel of the sub-chassis, upon engagement with the rail, friction between the dump pad 24 and rail under the weight force of the vehicle may provide a measure of additional braking force.

[0074] In the applied configuration, as can be seen in Figure 8C, the brake pads 35 are moved by the bias spring 25 toward one another into braking engagement with the sides of the head 3a of the rail thereby to generate frictional braking against the rails and retard movement of the bogie. In this embodiment, the calliper 21 is a floating or sliding type calliper. The brake unit comprises a calliper bracket 38 fixedly mounted to the sub-chassis and the calliper 21 is slidably mounted to the bracket on mounting pins. Upon activation, the bias spring pushes one brake pad against the rail while sliding the calliper 21 on its floating mount to draw the opposite pad toward the other side of the rail thereby clamping the rail between the brake pads.

[0075] Advantageously, the floating design allows the brake calliper 21 a degree of lateral adjustment such that under the influence of the rail, upon dumping of the chassis, the calliper will slide to compensate for minor lateral variation in the track gauge and/or lateral alignment of the bogie on the rails. In other embodiments a fixed calliper design may be used and the entire brake unit is mounted to float on the sub-chassis.

[0076] It will be appreciated that the amount of hydraulic fluid discharged from the brake release actuator cylinder will determine the degree to which the brake release actuator 27

2019200423 22 Jan 2019 allows the bias spring 25 to move the brake unit 10 from the release configuration to the applied configuration. When the brake unit 10 is activated, the pads 35 move together into clamping, braking engagement with the head 3a of the rail 3, taking up any free space therebetween until the unit 10 reaches the applied configuration and braking forces are generated. In the release configuration and during travel to the applied configuration, rubbing of one or both pads 35 on the rail may provide an incidental amount of calliper drag however no substantial braking forces are generated until the brake unit reaches the applied configuration.

[0077] Upon reaching the applied configuration, the clamping force exerted on the rail by the brake pads 35 (and corresponding braking force generated by the unit 10) increases as hydraulic fluid is discharged from brake release actuator 27, until the full application force of the bias spring 25 is applied to the rail 3 via the pads 35 and maximum braking is applied. It will be appreciated that the maximum braking force generated by the brake unit 10 will be directly proportional to the brake application force provided by the bias spring 25 and the coefficient of friction between the pad and the rails. As such both the brake application force and brake pad material are pre-selected in view of the weight, anticipated velocity of the vehicle and the incline of the track to ensure the brake unit applies a sufficient braking force to appropriately decelerate the vehicle.

[0078] Furthermore, the rate at which the brake unit 10 transitions from release configuration to the applied configuration, and then maximum braking force is provided, is directly dependant on the rate at which the brake release valve discharges hydraulic fluid from the brake release actuator 27. The time and rate at which the brake unit 10 transitions from release configuration to the applied configuration, are referred to herein as the (brake unit application rate) brake unit application time and brake application rate respectively. In this way the brake release valve is chosen to modulate the brake unit application rate and the time the brake unit takes to reach the applied configuration after activation.

[0079] In normal operation where emergency braking is not required, the emergency braking system is primed by pressurising the hydraulic dump actuators and the brake release actuator/s with hydraulic fluid via the hydraulic circuit. So primed, the hydraulic dump cylinders function to raise the sub-chassis 15 (and the suspended carriage) to the raised position above the rails and the brake release actuator/s holds each brake unit 10 in the release configuration with the respective sets of brake pads 35 spaced apart to receive a respective rail upon dumping. As such the emergency braking system is ready for activation.

2019200423 22 Jan 2019 [0080] As previously noted both the hydraulic dump and brake release actuators are connectable to a pressurised hydraulic fluid supply via hydraulic circuits. In this embodiment the dump actuators and the brake release actuators are part of the same hydraulic circuit which is connectable to a single hydraulic fluid supply 40 (shown in Figure 1). This allows both the hydraulic dump and brake release actuators to be pressurised, or supplied with hydraulic fluid at the same time from a single hydraulic fluid supply thereby reducing complexity and components of the system and simplifying operation.

[0081] In alternative embodiments, each of the hydraulic dump actuators and the brake release actuators may be connected to separate circuits and/or connectable to separate hydraulic supplies.

[0082] The pressurised hydraulic fluid supply 40 includes a hydraulic pump and a reservoir of hydraulic fluid. The hydraulic fluid supply may be carried by the rail vehicle. Alternatively, where two or more rail vehicles are connected to form a train, the hydraulic circuits of all bogies of the train may be co-connected allowing a single pressurised hydraulic supply to be used to pressurise multiple hydraulic dump actuators and brake release actuators on multiple bogies at the same time.

[0083] Once primed, to activate bogie braking, whether in an emergency or otherwise, hydraulic fluid from the hydraulic dump cylinders and the brake release actuator/s is discharged. This dumps the sub-chassis and the callipers downwardly towards the rails such that each rail 3 is received within the calliper slot 22 of a respective brake unit 10 whereby the brake pads 35 may grip the rails as each brake unit 10 is applied to generate a frictional braking force, thereby to arrest or retard vehicle motion. However, it will be recognised that the brake unit/s cannot begin applying a clamping force to the rail/s and thereby generate a braking force until the unit/s are in position with respective rails at least partially captured within each brake calliper between the brake pads.

[0084] In this respect the dump actuator/s and the brake release actuator/s are operatively connected to a brake activation controller 45 (see Figure 1) which co-ordinates brake activation of the system. When triggered the brake activation controller co-ordinates the dump release valve/s and the brake release valves such that said sub-chassis will dump to the lowered position prior to the brake unit initiating braking engagement with the rail.

2019200423 22 Jan 2019 [0085] In one form of the invention, the dump rate and brake unit application rate is preselected to ensure that the sub-chassis reaches a position with the rail sufficiently captured in the calliper well before the brake unit begins applying a braking force to the rail. More specifically, while the brake activation controller may initiate dumping of the bogie and activation of the brake unit simultaneously, the dump release valve/s are configured such that the dump rate is a substantially faster rate than the brake unit application rate. That is to say, the dump rate is selected such that the sub-chassis completely “dumps” or transitions from the raised to lowered position prior to the brake unit moving to the applied configuration. For instance, the system is configured such that dump time is less than the brake unit application time. Preferably, the dump time is less than one second and the brake unit application time is between 1 and 2 seconds. This ensures that the pads remain sufficiently withdrawn or spaced apart to allow the rail to be sufficiently captured in the calliper before the pads engage the rail.

[0086] In an alternative form of the invention the brake activation controller delays initiation of brake unit application after initiation of the dumping process such that the system completes the dump prior to the brake unit completely moving from the release configuration to the applied configuration. In other forms of the invention the brake activation controller delays initiation of brake unit application until the sub-chassis has completely transitioned from the raised to lowered position.

[0087] In one alternative embodiment, the dump release actuator may be replaced by dump release means to hold the bogie in the raised position and initiate dumping. The dump release means may comprise at least one of a mechanical linkage or catch, pneumatically or electrically operated dump release mechanism to activate dumping. The dump release means may further include a dump damper which controls the dump rate. The dump damper may include friction operated damping, hydraulically operated damping and/or pneumatically operated damping.

[0088] In another embodiment of the invention the brake release actuator may be replaced by brake release means to hold the brake unit in the release configuration and initiate brake application. The brake release means may comprise at least one of a mechanical catch, pneumatically or electrically operated brake release mechanism to activate brake application. The brake release means may include a brake application damper which controls the brake application rate. The brake application damper may include friction operated damping, hydraulically operated damping and/or pneumatically operated damping.

2019200423 22 Jan 2019 [0089] It will be appreciated that the invention provides significant advantages over the prior art. Since braking forces are applied directly to the rail heads and generated primarily due to the gripping force of brake calliper and brake pads on the rail, the system is able to generate substantially greater maximum braking forces than existing brake units. Furthermore, the braking force does not substantially rely on gravity or normal weight force and therefore is largely independent of the mass of the vehicle and inclination of the track. Furthermore the system of the invention is less dependent on tolerances of the rail-brake unit requiring less maintenance of the rail tracks. Advantageously the braking retardation force generated by the brake units can be adjusted to cater for different weight rail vehicles (for instance caused by variation in gross weight of an unloaded/partially loaded/fully loaded vehicle) by adjusting the brake application force of the calliper.

[0090] Another advantage is that the system is designed to be retrofitted to existing brake bogies thereby upgrading braking performance and safety of existing equipment.

[0091] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms a,” an, and the may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms comprises, comprising, “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0092] When an element or layer is referred to as being on, “engaged to,” connected to, or coupled to another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being directly on, “directly engaged to,” directly connected to, or directly coupled to another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term and/or includes any and all combinations of one or more of the associated listed items.

2019200423 22 Jan 2019 [0093] Although the terms first, second, third, etc. may be used herein to describe various elements, compartments, components, regions, layers and/or sections, these elements, components, compartments, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0094] Spatially relative terms, such as “inner,” “outer,” beneath, below, lower, above, upper, and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as below or beneath other elements or features would then be oriented above the other elements or features. Thus, the example term below can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0095] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0096] Similarly it should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, FIG., or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as

2019200423 22 Jan 2019 the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

[0097] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0098] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Claims (22)

Claims

1. A bogie for a rail vehicle comprising:

a chassis for mounting a pair of rail engaging rail wheels;

a sub-chassis mounted to the chassis and movable with respect to the chassis between a raised position and a lowered position, the sub-chassis including a mounting formation for supporting a body of the rail vehicle;

a hydraulic dump actuator disposed between the chassis and the sub-chassis and configured to selectively hold the sub-chassis in the raised position against a weight force, when supplied with pressurised hydraulic fluid;

at least one brake unit mounted to the sub-chassis, the brake unit comprising:

a brake calliper assembly for at least partially receiving a head of the rail when the sub chassis is moved into the lowered position;

a bias means for biasing the brake unit toward an applied configuration wherein the brake calliper assembly clamps the sides of the head of the rail in braking engagement;

a hydraulic brake release actuator configured to selectively hold said brake unit in a release configuration against an application force imposed by said bias means, when supplied with pressurised hydraulic fluid, and thereby to allow rail insertion into the calliper assembly; and wherein the dump actuator and the brake release actuator are configured for operative connection to a brake activation controller for selectively activating bogie braking by discharging hydraulic fluid from the hydraulic dump actuator and hydraulic brake release actuator thereby to dump the sub-chassis from the raised position to the lowered position, and allow the brake unit to transition from the release configuration to the applied configuration.

2. A bogie according to claim 1 wherein the brake control is operatively configured to dump the sub-chassis into the lowered position prior to the brake calliper assembly clamping the sides of the head of the rail in braking engagement.

3. A bogie according to claim 2 wherein said dump actuator includes a dump release valve for discharging hydraulic fluid from the dump actuator, said dump release valve operatively connected to the brake activation controller.

4. A bogie according to claim 3 wherein said brake release actuator includes a brake release valve for discharging hydraulic fluid from the brake release actuator, said brake release valve operatively connected to the brake activation controller.

2019200423 22 Jan 2019

5. A bogie according to claim 4 wherein the brake activation controller activates bogie braking such that the sub-chassis moves into the lowered position before the brake calliper assembly clamps the sides of the head of the rail in braking engagement.

6. A bogie according to claim 5 wherein the brake activation controller activates the dump release valve and the brake release valve simultaneously.

7. A bogie according to claim 6 wherein the sub-chassis dump time is substantially less than the brake unit application time.

8. A bogie according to claim 7 wherein the sub-chassis dump time is less than 1 second and the brake unit application time is between 1 and 2 seconds.

9. A bogie according to claim 5 wherein the brake activation controller activates the dump release valve prior to activating the brake release valve.

10. A bogie according to any one of the preceding claims wherein and the dump actuator is connected to a dump hydraulic circuit for supplying pressurised hydraulic fluid to the dump actuator.

11. A bogie according to any one of the preceding claims wherein the brake release actuator is connected to a brake release hydraulic circuit for supplying pressurised hydraulic fluid to the brake release actuator.

12. A bogie according to any one of the preceding claims wherein said brake calliper includes a pair of spaced, laterally opposed brake pads for braking engagement with the sides of the head of the rail.

13. A bogie according to any one of the preceding claims wherein the pair of laterally opposed brake pads are held at a closer spacing when the calliper is in the applied configuration than when the calliper is in the release configuration.

14. A bogie according to any one of the preceding claims wherein the brake calliper includes a dump pad within said calliper and disposed for engaging the superior surface of the head of the rail thereby limiting the downward movement of the sub-chassis and brake units.

2019200423 22 Jan 2019

15. A bogie according to any one of the preceding claims wherein the brake calliper is a spring applied hydraulic release brake.

16. A bogie according to any one of the preceding claims including at least two pairs of rail engaging wheels, each pair rotatably mounted to the chassis on respective axle members extending transversely across the bogie and defining the respective parallel wheel axes.

17. A bogie according to claim 13 wherein said chassis includes a pair of longitudinally disposed side members spaced on either side of the bogie centreline and connecting the axle members.

18. A bogie according to claim 14 wherein each side member includes a central recess to accommodate the sub-chassis.

19. A bogie according to any one of the preceding claims wherein the mounting formation includes a pivot for pivotable mounting of the bogie to the body of the vehicle.

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

21. A bogie for a rail vehicle comprising:

a chassis for mounting respective pairs of rail engaging wheels;

a sub-chassis mounted to the chassis and movable with respect to the chassis between a raised position and a lowered position, the sub-chassis including a mounting formation for supporting a body of the rail vehicle;

a dump actuator disposed between the chassis and the sub-chassis and configured to selectively hold the sub-chassis in the raised position;

at least one brake unit mounted to the sub-chassis, the brake unit comprising:

a brake calliper assembly for at least partially receiving a head of the rail when the sub chassis is moved into the lowered position;

a bias means for biasing the brake unit toward an applied configuration wherein the brake calliper assembly grips the sides of the head of the rail in braking engagement;

a brake release actuator configured to selectively hold said brake unit in a release configuration, against an application force imposed by said bias means to allow rail insertion into the calliper assembly; and wherein wherein the dump actuator and the brake release actuator are configured for

2019200423

22 Jan 2019

-24operative connection to a brake activation controller for selectively activating bogie braking by discharging hydraulic fluid from the hydraulic dump actuator and hydraulic brake release actuator thereby to dump the sub-chassis from the raised position to the lowered position, prior to the brake unit transitioning to the applied configuration.