AU2009202435B2 - Fluid pressure brake unit - Google Patents

Abstract

A fluid pressure brake unit (40, 40') for use in a chain of like units comprises a fluid port (BP) for connection to a brake pipe for providing a source of fluid to the unit at a first brake pipe pressure. Further fluid ports (ACC REL, DV, AUX RES) are provided for 5 connection to a plurality of fluid reservoirs or volumes. The unit (40, 40') is operable to effect charging and discharging of the reservoirs with fluid. The plurality of reservoirs includes an auxiliary reservoir. A main piston 1.45 is subjected to opposing pressures of brake pipe and auxiliary reservoir whereby on a predetermined reduction of brake pipe pressure below the first pressure on a first side of the piston 1.45, the unit is operatable 0 to effect brake application. A quick service feature (5, QS-CH) is operable upon said predetermined reduction of brake pipe pressure to effect a quick service reduction, being a sudden local reduction of pressure on said first side of the main piston 1.45 to affect other units in the chain. A quick service regulator 4 is operable to ensure the quick service reduction is within a predetermined pressure range below the first brake 5 pipe pressure. A surge suppressor 6 is responsive to operation of the quick service feature (5, QS-CH), to isolate the first side of the main piston 1.45 from the brake pipe for a predetermined period of time. The surge suppressor may be implemented with or without the quick service regulator (5, QS-CH).

Description

P100/011I Regulation 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Fluid pressure brake unit The following statement is a full description of this invention, including the best method of performing it known to us: 1A Fluid Pressure Brake Unit Field of the Invention The present invention relates to a fluid pressure brake unit. In particular, the invention relates to a triple valve for railway freight wagons. The invention may also have 5 application to other pneumatic braking systems. Background of the Invention The vast majority of the world's trains are equipped with braking systems which use compressed air to control the application and release of the brakes to thereby push brake blocks onto wheels to provide braking. These systems are known as "air brakes" 0 or "pneumatic brakes". Figure 1 is a diagrammatic illustration of one such braking system 10. Note that this is illustrative only and other configurations are possible. Additional safety mechanisms (not shown) and instrumentation (not shown) may also be employed. The compressor 16 draws air from atmosphere and compresses it for use on the train. 5 Its principal use is for the air brake system, although compressed air has a number of other uses on trains. The Main Reservoir 18 provides a storage tank for compressed air. The Driver's Brake Valve 20 is the means by which the driver controls the brake system 10. The brake valve 20 has an operating handle with (at least) the following operating positions: "Release and Charging", "Service Application Zone" and "Emergency". 20 The Brake Pipe 12 runs the length of the train to each successive wagon and transmits the variations in brake pipe pressure to control the brake 14 on each wagon. Changes in air pressure in the brake pipe 12 causes changes in the state of the brake 14 on each wagon. It can apply the brake, release it or hold it following a brake application. The system operates as a "fail safe" system, i.e. loss of air in the brake pipe 12 will cause 25 the brake to apply.

2 The system is initially charged with air when the operating handle of the brake valve 20 is in the Release and Charging position. This is described in detail below under "Charging Configuration". When the operating handle of the brake valve 20 is in the Service Application Zone, the 5 connection to the main reservoir 18 is closed off and the brake pipe 12 is opened to atmosphere allowing brake pipe air to escape and reduce pressure in the brake pipe. This is described in detail under the heading "Preliminary Quick Service" and "Service Application Configuration". The driver's brake valve 20 maintains the closed connection between the main reservoir 0 18 and the brake pipe 12 and also closes off the connection to atmosphere after a service brake application has been made. The brake pipe pressure is held substantially constant at the reduced pressure resulting from the service application. The amount of brake application is dependent upon the amount of handle movement throughout the Service Application Zone. 5 Most drivers' brake valves 20 are provided with an Emergency position. Its operation is the same as service application, except that the opening to atmosphere is larger to give a quicker application. Brake pipe pressure loss can be through a number of causes as follows: . a controlled reduction of pressure by the driver; 20 . a rapid reduction by the driver using the emergency position on the brake valve 20; . a rapid reduction by a conductor or guard who has an emergency valve at his location; . a rapid reduction by passengers using an emergency system (available on some 25 railways) to open a valve; 3 . a rapid reduction through a burst pipe or hose; or . a rapid reduction when the hoses part as a result of the wagons becoming parted or derailed. At the ends of each wagon, angle cocks 28 are provided to allow the ends of the brake 5 pipe hoses to be sealed when the wagon is uncoupled. Each wagon has at least one brake cylinder 30 and sometimes two or more are provided. The piston (not shown) inside the brake cylinder 30, moves in accordance with the change in air pressure inside the brake cylinder. The movement of the piston is transmitted to the brakes 14 via linkages called brake rigging 32. The brake rigging 32 10 applies the brake blocks 34 to the wheels 36. Overview of Triple Valve Each brake cylinder has an associated "triple valve" 40 so termed because it originally served three functions using a single slide valve. However, modern forms of the triple valve 40 are considerably more complex as will be understood from the discussion 15 below. Associated with each triple valve 40 is a multi-compartment reservoir 42 having discrete volumes including auxiliary reservoir 44, accelerated release reservoir 46, dummy volume 48 and supplementary volume 50. The triple valve performs the following functions: a) controls auxiliary reservoir and accelerated release reservoir charging; 20 b) applies the brake; and c) releases the brake. The various volumes in the multi-compartment reservoir 42 are connected to ports of the triple valve 40 and the relay 54 through a pipe bracket 52. The supplementary reservoir is not connected to the triple valve.

4 Basic Triple Valve Operation Charging During initial charging of brake system 10, triple valve 40 supplies air to auxiliary reservoir 44 and accelerated release reservoir 46. The supplementary reservoir 50 is 5 charged directly from the brake pipe through a charging check valve and choke. Service Application When the brakes are to be applied, there is a suitable reduction in pressure of brake pipe 12. The triple valve directs auxiliary reservoir 44 air into the dummy volume 48 depending on a pre-determined rate and the amount of brake pipe pressure reduction. 0 The pressure in the dummy volume serves as reference pressure for the brake cylinder pressure and application of brakes. Equalization of auxiliary reservoir and dummy volume pressures will result in a full application of the brakes. The reference dummy volume pressure is signal detected by relay valve 54, which feeds supplementary reservoir air into the brake cylinder to apply the brakes 14. 15 The amount of supplementary reservoir pressure allowed by the relay valve is conditioned by an air pressure signal generated by a load detector 56. When the wagon is unloaded, the relay valve 54 delivers a ratio of dummy volume pressure to the brake cylinder. In alternative non-relayed brake systems the supplementary reservoir 50 and the 20 dummy volume 48 may not be included, and the auxiliary reservoir pressure may be fed directly to the brake cylinder. Quick Service Feature The triple valve 40 also has a quick service feature which provides a local venting reduction of brake pipe air to the atmosphere during the preliminary application stage. The reason for this is that the time for the brake pipe pressure reduction to reach the 25 end of the train can be quite considerable. To overcome this difficulty, the quick service feature creates a sudden reduction in pressure, locally at the triple valve 40 which travels to the subsequent triple valve 40 and so on creating a pressure wave which 5 travels down the length of the train at almost the speed of sound, triggering the operation of the triple valves 40 in succession. To effect quick service action, the triple valve includes a quick service chamber to which the brake pipe air is vented during quick service action. The quick service chamber is 5 originally at atmospheric pressure. The quick service action is initiated by a brake pipe pressure reduction of approximately 10 kPa, initiated by the driver's brake valve 20. The majority of the quick service action is normally created by connecting the brake pipe to the quick service chamber (which is originally at atmospheric pressure). The flow of air into the quick service chamber creates a local pressure drop in the brake pipe pressure 0 which helps with propagating the brake pipe pressure reduction wave along the train. The quick service chamber may be disconnected from atmosphere during quick service and may not be vented until the brake is released. In order to avoid pressure surges which disrupt the pressure wave, the maximum quick service pressure reduction is limited to between 15kPa to 17kPa. 5 Generally, a triple valve 40 is provided on each wagon and controls the brake(s) 14 on each wagon. In some instances, wagons may be joined as tandems with a single triple valve controlling the brake on the tandem wagons. As will be appreciated, the location of the triple valve 40 on every second wagon increases the spacing between consecutive triple valves. When this spacing is increased considerably eg distances 20 exceeding 38 metres, there is difficulty in propagating the brake pipe reduction beyond about 80 wagons (or 40 tandems), in a train consisting of 150 wagons (or 75 tandems), particularly during light braking i.e. when the brake pipe reduction from the driver's brake valve 20 is at a minimum. There are several reasons for this phenomenon. Firstly, by increasing the triple valve 25 spacing, the volume of air in the brake pipe is also increased. Therefore, given that the quick service chamber volume is constant, the pressure drop at each triple valve will be reduced. Secondly, when the braking is light, the strength of the brake pipe pressure reduction wave is also at a minimum and therefore in some instances insufficient to overcome the spacing between the triple valves. Thirdly, the resistance to air flow in the 6 brake pipe 12, manifested as frictional losses, also impacts on the size of the brake pipe reduction wave. When a brake pipe reduction wave is not transmitted throughout the train during light braking, the problem can be exacerbated when the driver makes subsequent service 5 reductions in order to obtain the necessary braking force. This is because the triple valves which have achieved their quick service action, substantially present at the front of the train, have their quick service chambers filled with brake pipe air already, and therefore, unable to have their quick service feature assist with the brake pipe reduction wave. Therefore, despite the later heavier brake pipe reduction performed by the driver, 0 a brake pipe reduction wave may still not be sufficient to apply the triple valves that are positioned toward the end of the train. As a consequence, the number of tandem wagons that can be safely accommodated in a train is reduced. Thus, in such set-ups, the quick service feature on the triple valve is only ,making a limited contribution to the local brake pipe pressure reduction, sometimes as low as 5 5KPa, while the minimum required in order propagate the brake pipe reduction wave is 7KPa. It follows that the greater the local reduction, the stronger the propagation wave. However, beyond 17KPa, the strength of the signal can result in pressure surges that can travel back through the brake pipe and cause the unintended release of some of the triple valves, especially at the back of a long train. 20 It is an object of the present invention to address the foregoing disadvantages of triple service valves, or at least provide the public with a useful choice over known triple valves. The following description also deals with two prior art features of existing triple valves. These features are described here for the sake of completion. 25 Release In order to release the brakes 14 following application, the brake pipe pressure is increased. Dummy volume air is exhausted during release and the triple valve 40 also recharges the auxiliary reservoir 44 and the accelerated release reservoir 46. The 7 pressure change of the dummy volume 48 is detected by the relay valve 54 which subsequently releases the braking force. Accelerated Release Valve During release, the triple valve 40 also feeds stored accelerated release reservoir air 5 into the brake pipe 12 independent from the main piston system. This amplifies the release impulse which passes rapidly through the train. It is not admitted that any of the information in this specification is common general knowledge, or that the skilled addressee could be reasonably expected to have ascertained, understood or regarded it as relevant at the priority date. 0 Summary of the Present Invention In accordance with a first aspect of the present invention there is provided a fluid pressure brake unit for use in a chain of like units, the unit comprising: a fluid port for connection to a brake pipe for providing a source of fluid to the unit at a first brake pipe pressure; .5 fluid ports for connection to a plurality of fluid reservoirs or volumes, the unit operable to effect charging and discharging of the reservoirs with fluid, the plurality of reservoirs also including an auxiliary reservoir; a main piston subjected to opposing pressures of brake pipe and auxiliary reservoir, whereby on a predetermined reduction of brake pipe pressure below the first brake pipe 20 pressure on a first side of the piston, the unit is operatable to effect brake application; a quick service feature operable upon said predetermined reduction of brake pipe pressure to effect a quick service reduction, being a sudden local reduction of pressure on said first side of the main piston to affect other units in the chain; and 8 a quick service regulator operable to ensure the quick service reduction is within a predetermined pressure range below the first brake pipe pressure. The quick service feature includes a quick service chamber. The unit is suitably operable to connect to the quick service chamber to atmosphere via a non-choked exhaust. Upon the predetermined 5 reduction of brake pipe pressure on said first side of the piston, the unit is operable to open a connection between the first side of the piston and the quick service chamber. The quick service regulator preferably compares the pressure on the first side of the main piston with the pressure of the reference reservoir to ensure the desired quick service reduction. In a most preferred form of the invention, the quick service regulator compares 10 the pressure in the quick service chamber with that of a reference reservoir which maintains a substantially constant pressure during brake application. Most preferably, the two pressures being compared act on opposite sides of a diaphragm valve. The pressure in the quick service chamber and a spring may act on one side of the diaphragm with the pressure of the reference reservoir acting on the other side of the diaphragm. The two opposing 15 pressures may act across equal areas. Alternatively, other arrangements are possible e.g. the two pressure may act across unequal areas. When the combined effect of the quick service chamber pressure and the spring exceeds that of the reference reservoir, the diaphragm valve will open, preferably exhausting the quick service chamber to atmosphere, until the quick service chamber pressure and the 20 spring force equalise with the reference reservoir pressure. The quick service chamber's exhaust into atmosphere may be choked. Thus, it will be understood that the diaphragm valve will remain open whenever the pressure differential between the quick service chamber (or the first side of the piston) and the reference reservoir drops below a predetermined level. When the pressure differential reaches the predetermined level or 25 above, the diaphragm valve closes, closing the connection of the quick service chamber to atmosphere. In a preferred form of the invention, the desired quick service reduction is about 15kPa. The desirable range of quick service reduction is about 15 to 17kPa. Preferably the 9 quick service regulator provides a constant quick service reduction, triggered by a predetermined reduction of brake pipe pressure, regardless of the length of the brake pipe. Preferably, the fluid pressure brake unit operates on pneumatic pressure. The fluid 5 pressure brake unit may comprise a triple valve for a braking system on a railway wagon. In such railway braking systems, pneumatic pressure may be carried by a brake pipe which runs the length of the train to each successive wagon. The brake pipe transmits variation in brake pipe pressure to control the brake on each wagon. Each wagon may therefore have a triple valve responsive to the variations in brake pipe 0 pressure. Alternatively, in other arrangements, the wagons may be configured in tandems, with one triple valve per tandem. In a preferred form of the brake unit, the port for connection to the reference reservoir may comprise a port to the accelerated release reservoir. The brake unit preferably operates so as to charge the accelerated release reservoir with brake pipe air during 5 charging and retain the charged pressure during brake application so that during brake release, the accelerated release reservoir air may pass into the brake pipe to create a release impulse which is locally amplified and passes rapidly through the train. Thus, the substantially constant accelerated release reservoir may serve as a reference reservoir during braking. 20 In an alternative form of brake unit, an emergency reservoir/volume may be used as the reference reservoir - North American systems utilise an emergency reservoir for their emergency and accelerated release features. Other triple valves known as "Distributors" or "Control Valves" have a control reservoir which could be used for this reference pressure or another separate titled reservoir could be used. However the pressure in 25 the reservoir is suitably reduced and recharged during brake release otherwise overcharge would be an issue. The brake unit may include ports to other reservoirs including a dummy volume, the function of which will be understood by those skilled in the art. Additionally, the unit may include a dummy volume exhaust.

10 Also described herein is a fluid pressure brake unit for use in a chain of like units, the unit comprising: a fluid port for connection to a brake pipe for providing a source of fluid to the unit; fluid ports for connection to a plurality of fluid reservoirs or volumes, the unit operable to effect charging and discharging of the reservoirs with fluid, the plurality of 5 reservoirs also including an auxiliary reservoir; a main piston subjected to opposing pressures of brake pipe and auxiliary reservoir, whereby on a predetermined reduction of brake pipe pressure on a first side of the piston, the unit is operatable to effect brake application; a quick service feature operable upon said predetermined reduction of brake pipe pressure to effect a quick service reduction, being a sudden local reduction 10 of pressure on said first side of the main piston to affect other units in the chain; and a surge suppressor responsive to operation of the quick service feature, to isolate the first side of the main piston from the brake pipe for a predetermined period of time. Preferably, the quick service feature includes a quick service chamber, whereby, upon the predetermined reduction of brake pipe pressure on said first side of the piston, the 15 unit is operable to open a connection between the first side of the piston and the quick service chamber and to connect the quick service chamber to atmosphere. The surge suppressor may include a piston, responsive on one side thereof to pressure in the quick service chamber to close a connection between the brake pipe and the first side of the main piston. The piston may have a choked passage from said one side to the 20 other, to provide for equalisation of the pressure on both sides of the piston to permit opening of the connection between the brake pipe and the first side of the main piston after said predetermined period of time. Preferably, the predetermined period of time is about two seconds. The unit may incorporate a quick service regulator operable to ensure the quick service 25 reduction is within a predetermined pressure range below the original brake pipe pressure. Preferably, where surge suppression is provided, the predetermined pressure range for quick service reduction is in the range of about 7-17 kPa. The minimum allowed pressure drop for a quick service in order to propagate is 7kPa. This pressure would be expected at a maximum brake pipe volume condition. For a maximum brake 11 pipe length of 50m, the quick service chamber is designed to provide the minimum of 7kPa pressure drop. However, because the maximum allowable pressure drop, for quick service, is 17kPa, the minimum brake pipe length is limited to 20.5m. Therefore, the valve would have a quick service pressure drop working range of 7-17kPa, 5 achievable on railcars with brake pipe lengths between 20.5m and 50m. It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention. o Brief Description of the Drawings In order that the invention may be more fully understood, one embodiment will now be described, by way of example, with reference to the figures in which: Figure 1 is a schematic illustration of the main components of a railway braking system according to the prior art; 5 Figure 2 is a cross sectional view of a triple valve in accordance with a preferred embodiment of the present invention, the triple valve being shown in an unpressurised configuration; Figure 3 is a cross-sectional view of the triple valve of Figure 2 shown in the charging configuration; 20 Figure 4 is a cross-sectional view of the triple valve of Figure 2 shown in the preliminary quick service configuration; Figure 5 is a cross-sectional view of the triple valve of Figure 2 shown in the service application configuration; Figure 6 is a cross-sectional view of the triple valve of Figure 2 shown in the service lap 25 configuration; 12 Figure 7 is a cross-sectional view of the triple valve of Figure 2 shown in the release configuration; Figure 8 is a cross-sectional of the triple valve of Figure 2 shown in the release configuration with accelerated released and retarded recharge; 5 Figure 9 is a cross-sectional view of the triple valve of Figure 2 shown in the emergency configuration; Figure 10 is a cross-sectional view of a triple valve according to a second embodiment of the present invention shown in un-pressurized configuration; Figure 11 is a cross-sectional view of the triple valve of Figure 2 shown in the charging 0 configuration; Figure 12 is a cross-sectional view of the triple valve of Figure 2 shown in the preliminary quick service configuration; Figure 13 is a cross-sectional view of the triple valve of Figure 2 shown in the service application configuration; 15 Figure 14 is a cross-sectional view of the triple valve of Figure 2 shown in the service lap configuration; Figure 15 is a cross-sectional view of the triple valve of Figure 2 shown in the release configuration; Figure 16 is a cross-sectional view of the triple valve of Figure 2 shown in the release 20 configuration with accelerated release and retarded recharge; Figure 17 is a cross-sectional view of the triple valve of Figure 2 shown in the emergency configuration.

13 Detailed Description of the Embodiment shown in the Figures Details of First Embodiment Triple Valve The first embodiment triple valve 40 is equipped with the following subcomponents (See Figure 2): 5 Service Main Piston System 1; Accelerated Release Valve 2; Inshot and Reduction Ensuring Valve 3; Quick Service Regulating Valve 4; and Quick Service Valve 5. 0 Further the triple valve 40 has a number of ports on the left hand side as shown, to the following volumes/air sources including: Brake Pipe (BP); Accelerated Release Reservoir (ACC. REL.); Dummy Volume (DV); 15 Dummy Volume Exhaust (D.V. Exh); and Auxiliary Reservoir (AUX. RES.). Further details of the triple valve will be understood from the detailed description of the operation which follows: 14 Operation In Figure 2, the triple valve 40 is shown in unpressurised condition. Figure 3 illustrates the configuration during charging. 1. Charging Configuration 5 Compressed air from the brake pipe 12 flows into the pipe bracket 52 and is ported to the triple valve 40 via an isolating cock and filter (neither shown). During charging, brake pipe air pressurises the following valve components: Ia. Service Main Piston System (1) The service main piston system 1 includes a main piston 1.45 including a top follower 0 1.46 and a bottom follower 1.47. An auxiliary reservoir charging valve v1.6 and a balancing valve v1.7 are equally spaced on either side of the main piston 1.45, and are mechanically operated by having the upper end of their valve stems bear against the bottom side of the bottom follower 1.47. In the lower position of the main piston as shown, the auxiliary reservoir charging valve v1.6 is held in such a position against the 5 bias of spring 1.60 such that the valve seat v1.8 is open. The balancing valve v1.7 has two valve seats, v1.9 and v1.10. The inner valve seat v1.9 communicates with an inner bore within the stem of the balancing valve v1.7. The outer valve seat v1.10 communicates the space beneath the balancing piston 1.59 with the chamber below it (in the region of springl.61). This chamber communicates with 20 exhaust chamber 1.7 via balancing valve choke 1.8. On charging, brake pipe air flows through to the space above the main piston 1.45, the valve seat area V1.3 of the quick service inlet valve, and flows to the accelerated release valve 2. Further, air flows from the brake pipe via the charging check valve and choke C1.6 and 25 the open valve seat V1.8 to the volume below main piston 1.46. This pressurises the upper side of balancing piston 1.59 above the smaller diameter seal 1.54. The balancing piston 1.59 has three chambers: the bottom chamber 1.56 or the space 15 beneath it; the centre chamber 1.57 which is positioned between the two seals 1.54, 1.55; and the upper chamber 1.58 which is the small chamber below the stem of the bottom follower. The centre chamber 1.57 is always connected to atmosphere via exhaust chamber 1.7 5 and is not connected to any other porting internally in any operating position. Air further flows from beneath the main piston 1.45 to the dummy volume inlet valve 1.38.1 which is forced by spring 1.37 onto its outer seat v1.1, thereby holding the valve in a closed configuration. It is noted that the top of the service main piston stem 1.41 features dummy exhaust valve seat v1.2 which is open in its position as shown. The 0 open valve seat v1.2 enables communication between the dummy volume and the dummy exhaust via the hollow bore of service main piston stem 1.41. As previously mentioned, the dummy volume serves as a reference volume for braking operation. With the dummy volume connected to exhaust, the brakes will be released. Air from beneath the main piston 1.45 also flows to the inner valve seat V1.9 through 5 the inner bore in the stem of the balancing valve v1.7. The inner valve seat v1.9 is closed because of the lowered position of the main piston 1.45. It will be appreciated that the bottom chamber 1.56 underneath balancing piston 1.59 communicates with the outer valve seat v1.10 which is shown in the open configuration because of the stem of the balancing valve v1.7 is held by the main piston 1.45 against 20 the action of spring 1.61. Thus the space underneath balancing piston 1.59 communicates with the exhaust port 1.7 via balancing valve choke C1.7. Air from beneath the main piston 1.45 also flows to the quick service valve 5, in particular to the region above quick service piston 5.104. Finally, it will be understood that the auxiliary reservoir is charged from the air below the 25 main piston 1.45 via conduit 1.21. Additional auxiliary reservoir charging is accomplished by air flow via stability choke C1.3.

16 Thus, it will be understood that the auxiliary reservoir 44 is charged directly by the service main piston system 1. During charging, it can happen that a pressure differential is created by chokes C1.6 and C1.3 across the main piston 1.45 e.g. the pressure above the main piston 1.45 5 exceeds the pressure below the main piston by a predetermined value, then the main piston 1.45 will move downwardly into a retarded recharge position (see Figure 8). This results in the stem 1.95.1 of the auxiliary reservoir charging valve v1.6 being forced downwardly by the underside of the bottom follower 1.47, against spring 1.60 so that the disc with the retarted charging choke C1.4 bears against the sealing ring 1.100 so that 0 charging of the auxiliary reservoir is only permitted through the retarded charging choke C1.4. This provides two stages of charging and recharging. The stage selected is dependent on the location of the triple valve in the train consist. A more uniform charging throughout the train is accomplished by retarding the charging of the auxiliary reservoir on wagons which are located toward the front of the train. 5 This assists in the propagation of the pressure rise through the brake pipe to the rear of the train and so brings about a more even and quicker release, recharge and subsequent operation of the train. The main piston 1.45 returns to open charging position when brake pipe 12 and auxiliary reservoir pressures approach equalisation. In order to charge the accelerated release reservoir 46, the brake pipe air flows via the 20 choke C1.5, the open valve seat V1.5, the accelerated release reservoir charging check valve 1.62. The air then flows to the accelerated release valve 2 and via the pipe bracket 52 into the accelerated release reservoir 46. 1b. Accelerated Release Valve (2) In the accelerated release valve 2, both sides of diaphragm 2.83 are connected to the 25 atmosphere via the dummy exhaust port. Accelerated release reservoir air flows to the closed valve seat V2.2 via high sensitivity back flow check valve 2.89 which is open because the pressure exceeds the bias of light spring 2.90.

17 1c. Quick Service Regulating Valve (4) The right side of the diaphragm 4.74 is connected to atmosphere via the quick service chamber QS-CH as will be understood from the immediately following discussion of the quick service valve. The left side of diaphragm 4.74 is pressurised with accelerated 5 release reservoir air. Because the right side of the diaphragm is vented to the atmosphere, the diaphragm 4.74 is forced on its right-hand stop against the force of spring 4.90. Simultaneously, the check valve is forced on valve seat V4.1 by the force of spring 4.91 as a consequence of being linked by valve stem 4.2. 1d. Quick Service Valve (5) 0 The quick service valve piston controls the flow of quick service air to atmosphere. Auxiliary reservoir air in the volume below main piston 1.45 also pressurises the upper area of piston 5.104. The piston 5.104 is thereby forced downward and opens valve seat V5.1 against the force of spring 5.108. This enables the quick service chamber to vent to atmosphere via the exhaust port 1.7 and exhaust flap 1.75. 15 2. Preliminary Quick Service Configuration Referring to Figure 4, when an application of the brakes is required, this must be initiated by a brake pipe reduction of a minimum predetermined rate. A minimum predetermined rate is required since otherwise small fluctuations in brake pipe pressure (which would be the norm under normal operating conditions) could cause the brakes to 20 apply inadvertently. The following sequence occurs during "Preliminary Quick Service": 2a. Service Main Piston System 1 and Quick Service Valve 5 The service main piston 1.45 compares brake pipe and auxiliary reservoir pressures acting on equal areas on its upper and lower sides respectively. During brake pipe pressure reduction, the auxiliary reservoir charging check valve 1.5 25 prevents auxiliary reservoir air flow to brake pipe via the charging choke C1.6. Instead, flow is permitted through smaller orifice of the sensitivity choke C1.9. The flow of air 18 from auxiliary reservoir to brake pipe is also permitted through stability choke C1.3. Thus, the flow of air from auxiliary reservoir to brake pipe (caused by the reduction in brake pipe pressure) is controlled by the sensitivity choke C1.9 and the stability choke C1.3. 5 The pressure difference building up across the main piston 1.45 moves the main piston 1.45 upward and opens the quick service inlet valve seat V1.3 at a value primarily defined by the spring 1.43. Brake pipe air flows to quick service chamber (QS-CH.) via the restricted cross section between the upper end of the stem of main piston 1.45 and the free flow area of valve seat V1.3. The valve seat V5.1 in the quick service valve 0 remains open so air from the quick service chamber (QS-CH.) is vented to the atmosphere via open valve seat V5.1 and choke C5.1 of the quick service valve. This increases the pressure differential across the main piston 1.45 and accelerates its upward movement. Upward movement of the main piston 1.45 lifts the quick service inlet valve 1.38.2, 5 enabling the quick service pressure to bear against the service main piston stem 1.41 and move it upwardly relative to the spring guide 1.44. The valve seat v1.1 is moved into a position bearing against valve 1.38.1. Thus, the passage that previously existed from dummy volume to dummy exhaust via valve seat V1.2 is closed. The valve seat V1.1 is still closed at this time. 20 Because the main piston 1.45 has risen, the valve stem in the auxiliary reservoir charging valve v1.6 rises with the bias of spring 1.60 to close. Thus the charging connection from brake pipe to auxiliary reservoir via valve seat V1.8 is closed. Additionally, again because the main piston 1.45 has risen, valve stem of balancing valve V1.7 also rises closing valve seat V1.10. However, the inner valve seat V1.9 25 opens, pressurising the bottom chamber 1.56 underneath the balancing piston 1.59 and the piston 5.104 of the quick service valve 5 with auxiliary reservoir air. The balancing piston 1.59 moves upward, bearing against the spring guide 1.67 which acts on the balancing spring 1.69 and introduces a force into the service main piston system 1.

19 2b. Inshot and Reduction Ensuring Valve 3 Air which has entered the quick service chamber QS-CH through quick service inlet valve seat V1.3 flows through choke C3.1, and opens the return flow check valve 3.12.2 and passes across the open valve seats V3.1 and V3.2 to the left side of the diaphragm 5 3.74 and on to the dummy volume. The influx of air to the dummy volume is to a predetermined value depending on the spring 3.76. This flow of air into the dummy volume from the Quick Service Chamber QS-CH (which is also permitted to exhaust through exhaust chamber 1.7) adds to the reduction of brake pipe pressure which was created by the connection of brake pipe to the quick service chamber. This causes a 10 sudden reduction in brake pipe pressure which is sufficient to send a pressure wave down the length of the brake pipe at a speed close to the speed of sound, triggering downstream valves into operation. This provides a quick response of all the triple valves in the train and reduces in-train forces and slack action which can cause damage. It also ensures that all triple valves respond to an initial minimum reduction of brake pipe 15 pressure. The Inshot and Reduction Ensuring Valve 3 assures a predetermined minimum dummy volume pressure by connecting quick service chamber to the dummy volume 48. This ensures the delivery of sufficient air pressure to the brake cylinder to overcome the brake rigging friction and brake cylinder piston return spring and provides some braking 20 force. 2c. Quick Service Regulating Valve 4 The quick service regulating valve opens during initial brake application to regulate the brake pipe reduction to a predetermined value during quick service action. Air from the quick service chamber flows to the right side of the metal reinforced 25 diaphragm 4.74 and combined with the force of the spring 4.90 overbalances the force of accelerated release reservoir air on the left side and opens the valve seat V4.1 to allow quick service chamber air to exhaust (at EX). This exhaust may be choked or the orifice size controlled for stability purposes. Once the air in the quick service chamber reduces to a predetermined pressure the force of accelerated release reservoir air on 30 the left side of the diaphragm 4.74 overcomes the 20 combined force of the spring 4.90 and the reduced quick service air pressure on the right side and closes the valve seat V4.1. Thus, the quick service regulating valve's diaphragm 4.74 compares the force of accelerated release reservoir pressure against the combined force of quick service 5 chamber pressure and the control spring 4.90 over equal areas. Because the accelerated release reservoir air is constant at this point, this provides a fixed reference to ensure that the quick service reduction is at the predetermined value. The adopted configuration of the triple valve 40 is referred to as the "Preliminary Quick Service Configuration". 0 3. Service Application Configuration Once the initial quick service activity has ceased, the triple valve changes from the "Preliminary Quick Service" configuration to the "Service Application" configuration as explained below. 3a. Service Main Piston System (1) 5 As shown in Figure 5, piston 5.104 of the quick service valve will be pressurised with auxiliary reservoir air underneath seal 5.100, while above the seal 5.100 is open to atmosphere via exhaust chamber 1.7. Also, the area under seal 5.100 is larger than the air at the top of the quick service piston 5.104. This moves the piston upward, allowing check valve 5.32 to seal valve seat V5.1 under the force of spring 5.108. Thus, the 20 quick service chamber is isolated from atmosphere but remains connected to brake pipe pressure via valve seat V1.3. The main piston 1.45, the quick service inlet valve 1.38.2 and the spring guide 1.44 move further upward until the quick service inlet valve 1.38.2 applies force to the service main piston stem 1.41. This results in lifting the dummy volume inlet valve 1.38.1 25 against the bias of spring 1.37, from the valve seat V1.1 and opens a flow path from auxiliary reservoir to dummy volume. Dummy volume air flows to the dummy volume via the pipe bracket 52 and to the left side of the diaphragm 3.74 in the inshot and reduction 21 ensuring valve (3). The pressure in the dummy volume serves as a reference causing the brakes to apply. During brake applications of less than a full service reduction air flows from the auxiliary reservoir to the dummy volume until the auxiliary reservoir pressure is reduced to equalise with brake pipe pressure in the service lap 5 configuration. Auxiliary reservoir will equalise with the dummy volume when the brake pipe is reduced to or below this equalisation pressure. The size of the auxiliary reservoir and the size of the dummy volume are designed to provide a pressure equalization of 350 kPa from a regulated brake pipe auxiliary reservoir pressure (in the release and fully charged condition) of 500 kPa. In other words, if the auxiliary reservoir was 0 charged to 500 kPa and then connected to the dummy volume which is at atmospheric pressure the combined auxiliary reservoir and dummy volume would equalise at 350 kPa. On the Australian railway network the brake pipe is reduced to below this pressure during a full service application. The valve stem 1.50 of the balancing valve v1.7 follows the main piston 1.45 by the 5 force of spring 1.53 until it reaches its upper stop. At this point, the inner balancing valve v1.9 remains open retaining the connection between auxiliary reservoir air beneath main piston 1.45 and the bottom chamber 1.56. The balancing piston 1.59 moves to its upper stop under the force of auxiliary reservoir pressure underneath it. This limits the amount of upward bias applied by the balancing piston 1.59 to the main piston 1.45. 20 3b. Inshot and Reduction Ensuring Valve (3) As mentioned above, dummy volume air pressurises the left side of diaphragm 3.74 and moves it against the force of spring 3.76 to its right. As soon as the dummy volume pressure has reached a predetermined value, diaphragm 3.74 rests against spring guide 3.75. 25 This movement results in closing valve seat V3.2 with check valve 3.12.1 by the force of the spring 3.79 and interrupts the flow between quick service chamber and dummy volume. The return flow check valve 3.12.2 closes the valve seat V3.1 by spring force 3.79 and prevailing pressure.

22 4. Service Lap Configuration The purpose of the lap position is to allow a partial application of the brakes to be held constant. 4a. Service Main Piston System (1) 5 As discussed above, during a service brake application, the dummy volume is charged from the auxiliary reservoir by the service main piston system 1. As soon as the auxiliary reservoir pressure (acting below the main piston 1.45) is reduced to approximately the value of the brake pipe pressure (acting above the main piston 1.45), the service main piston system 1 moves from the elevated service position to the 0 service lap configuration illustrated in Figure 6. In this configuration, valve seat V1.1 is closed and the flow path between auxiliary reservoir and dummy volume is interrupted. The balancing piston 1.59 acts on the balancing spring 1.69 through the spring guide 1.67. This introduces a defined force in the service main piston 1.45, which stabilizes (holds) it in the service lap position. 5 Thus, the level of brake pipe reduction will determine the volume of air which passes from the auxiliary volume to the dummy volume when in the service application configuration because for greater degrees of brake pipe reduction, the greater the reduction of the auxiliary reservoir pressure to drop to the brake pipe pressure to bring about the service lap configuration. Thus, the degree of brake pipe reduction will affect 20 the relative pressures between the auxiliary reservoir and dummy volume as detected by the relay and will therefore relate to the braking force. Brake pipe and auxiliary reservoir are connected through the very small stability choke C1.3 which determines the release stability. The accelerated release reservoir charging choke C1.5 and check valve v1.5 25 arrangement prevents return flow of accelerated release reservoir air into the brake pipe in the application position.

23 During a further brake pipe reduction, the service main piston system will again move to the service application configuration (Figure 5), and the flow path from auxiliary reservoir to dummy volume will be opened. Subsequently, the same procedure as described above will take place and move the service main piston 1.45 back again to 5 service lap position. The reduction of brake pipe pressure and hence the increase in dummy volume pressure can be continued until the auxiliary reservoir pressure is equal to the dummy volume pressure. This will be detected by the relay and will correspond to a full application of the brakes. A further reduction of brake pipe pressure does not affect the level of the dummy volume pressure during a service application but moves 0 the main piston system 1 to the service application configuration. 4b. Inshot and Reduction Ensuring Valve (3) The inshot and reduction ensuring valve assures a predetermined minimum dummy volume pressure. Should the dummy volume pressure drop below this value - for example, due to leakage - the inshot and reduction ensuring valve will open and feed 5 brake pipe pressure via the quick service chamber to dummy volume. (See Figure 4) 5. Release From Service Configuration To release the brakes, the brake pipe pressure has to be increased by a predetermined margin above the level of the auxiliary reservoir pressure of the individual triple valve. The complete release sequence is shown in figures 7 and 8. 20 Sa. Service Main Piston System 1 The increase of brake pipe pressure produces a pressure difference at the main piston 1.45. The pneumatic force acts against the mechanical force of the balancing spring 1.69. At a predetermined pressure difference, the main piston 1.45 moves downward and contacts the valve stem 1.50 of the balancing valve. 25 The service main piston stem 1.41 remains in the service lap position under the action of the quick service pressure, while the spring guide 1.44 and the quick service inlet valve 1.38.2 follow the main piston 1.45 by spring force 1.43. The valve seat V1.2 of the dummy volume exhaust valve is still closed during this release stage.

24 Further downward movement of the main piston 1.45 closes inner valve seat V1.9 and opens outer valve seat V1.10 of the balancing valve through valve stem 1.50. Accordingly, auxiliary reservoir air in the bottom chamber 1.56 under the balancing piston 1.59 and under the piston 5.104 of the quick service valve 5 starts to vent to 5 atmosphere via choke C1.7. The main piston 1.45 moves further into the release position as a result of pressure reduction in the bottom chamber 1.56 under the balancing piston 1.59. 6. Accelerated Release and Retarded Recharge As discussed below under "Accelerated Release Valve 2", the accelerated release valve 0 2 is triggered during release of a service application. When triggered, the accelerated release reservoir air passes into the brake pipe creating a release impulse which is locally amplified and passes rapidly through the train. 6a. Service Main Piston System 1 and Quick Service Valve 5 During further downward travel of the service main piston 1.45, the following functions 5 are performed: As the air in bottom chamber 1.56 beneath the balancing piston is now connected to the atmosphere, the balancing piston 1.59 will move downward toward its lower stop. The connection between dummy volume and dummy exhaust is opened after the gap between spring guide 1.44 and the end of the service main piston stem 1.41 has been 20 exceeded by the further travel of the service main piston system to the release position. Dummy volume pressure is vented through open valve seat V1.2 and via the release choke C1.8 to atmosphere. Subsequently, the charging connection from brake pipe to auxiliary reservoir is opened by the valve stem 1.95.1. After the balancing piston 1.59 has moved downward to its lower stop, the flow path from brake pipe to quick service 25 chamber is safely closed by the quick service inlet valve 1.38.2, which seals on valve seat V1.3.

25 As soon as the auxiliary reservoir air under piston 5.104 has been vented to atmosphere via choke C1.7, the quick service valve piston 5.104 opens the flow path for quick service chamber air to atmosphere, via valve seat V5.1 and choke C5.1. As long as the pressure differential between brake pipe and auxiliary reservoir across 5 the main piston 1.45 exceeds the forces of the balancing spring 1.69 and the charging valve spring 1.60 and the balancing valve spring 1.61, the service main piston system is locked to its lower stop in the retarded recharge position. This allows the valve stem 1.95.1 to seat on the sealing ring 1.100, and charging of auxiliary reservoir is now performed via choke C1.6 and the retarded charging choke C1.4. When the pressure 0 difference drops, the service main piston moves back to the charging lap position (See Figure 2), and only choke C1.6 determines the further charging time. 6b. Accelerated Release Valve (2) The accelerated release valve 2 has a metal reinforced rubber diaphragm 2.83. The accelerated release valve 2 has the dummy volume exhaust acting across it as shown 5 on equal areas with a timing choke 2.84 in one chamber. The operation of the accelerated release valve is independent of the operation of the main piston 1.45. The accelerated release valve is triggered by dummy volume air that is retained by exhaust choke C1.8 when the dummy volume connects to dummy exhaust. The dummy volume air flows unrestricted to the right-hand side of the 20 diaphragm 2.83 (but not to the left because that is choked by timing choke 2.84 ) and overcomes the force of the spring 2.87 moving the diaphragm 2.83 to its left stop and lifting check valve 2.38 from the valve seat V2.2. Thus a flow path is established from accelerated release reservoir to brake pipe via the backflow check valve 2.89 and valve seat V2.1. This flow path remains open until brake pipe and accelerated release 25 reservoir pressures have nearly equalized. Then the backflow check valve 2.89 closes against the valve seat V2.1. Further, when the restricted flow of dummy volume air on the left side of diaphragm and the force of the spring 2.87 overbalance the force on the right side of the diaphragm 26 2.83, the diaphragm 2.83 moves back to its right-hand stop position closing the valve seat V2.2. 7. Emergency Application Configuration 7a. Service Main Piston System 1 5 The service main piston system operates during an emergency application in general as described in figures 4 and 5. However, deviating from above, the main piston 1.46 is forced against its upper stop by auxiliary reservoir pressure, because brake pipe pressure is completely vented as shown in figure 9. The stability choke C1.3 is closed by sealing ring 1.99. Auxiliary 1o reservoir and brake pipe are separated. A constant connection between auxiliary reservoir and dummy volume pressures remains open via valve seat V1.1 The return flow check valve 3.12.2 of the Inshot and Reduction Ensuring Valve 3 prevents the flow of dummy volume air to atmosphere during emergency applications. The foregoing describes only one embodiment of the present invention and 15 modifications may be made thereto without departing from the scope of the present invention. Details of Second Embodiment Triple Valve The second embodiment triple valve 40' is equipped with the following subcomponents (see Figure 10). The second embodiment is similar to the first embodiment and like 20 numerals will be used to represent like parts. Service Main Piston System 1; Accelerated Release Valve 2; In-shot and reduction Ensuring Valve 3; 27 Quick Service Regulating Valve 4; Quick Service Valve 5; Surge Suppression Valve 6; Further the Triple Valve 40' has a number of ports on the left hand side as shown, to the 5 following volumes/air sources including: Brake Pipe (BP); Accelerated Release Reservoir (ACC. REL); Dummy Volume (DV); Dummy Volume Exhaust (DVExh); 0 Auxiliary Reservoir (AUX. RES) Operation In Figure 10, triple valve 40' is shown in un-pressurised condition. Figure 11 illustrates the configuration during charging. 1. Charging Configuration 15 Compressed air from the brake pipe flows into the pipe bracket 52 (Fig 1) and is ported to the triple valve via an isolating cock and filter (not shown). During charging, brake pipe air pressurises the following valve components: 1a. Service Main Piston System (1) As best shown in Figure 10, the service main piston system 1 includes a main piston 20 1.45. An auxiliary reservoir charging valve v1.6 and a balancing valve v1.7 are equally spaced on either side of the main piston 1.45, and are mechanically operated by having 28 the upper end of their valve stems bearing against the bottom side of main piston 1.45. In the lower position of the main piston 1.45 as shown in Figure 11, the auxiliary reservoir charging valve v1.6 is held in such a position against the bias of spring 1.60 that valve seat V1.8 is open. 5 Balancing valve v1.7 consists of a check valve which has two valve seats, v1.9 and v1.10. The inner valve seat v1.9 communicates with an inner bore within the stem of the balancing valve v1.7. The outer valve seat v.1.10 communicates the space beneath balancing piston 1.59 with the chamber below it (in the region of spring 1.61). This chamber communicates with exhaust chamber 1.7 via balancing valve choke C1.7 0 On charging, the brake pipe air flows through the open surge suppression valve check valve seat V6.1 to the space above the main piston 1.45, the valve seat area V1.3 of the quick service inlet valve 1.38.2, and flows to the accelerated release valve 2. The flow of the brake pipe air is depicted by shading in Figure 11. Further, air flows from the brake pipe via auxiliary reservoir charging check valve and 5 choke C1.6 and the open valve seat V1.8 to the volume below main piston 1.45. This pressurises the upper side of balancing piston 1.59 above the smaller diameter seal 1.54. The balancing piston 1.59 has three chambers: the bottom chamber 1.56 or the space beneath it; the centre chamber 1.57 which is positioned between the two seals 1.54 and 1.55; and the upper chamber 1.58 which is the small chamber below the stem 20 of the bottom follower of the main piston 1.45. The centre chamber 1.57 is always connected to the atmosphere via exhaust chamber 1.7 and is not connected to any other porting internally in any operating position. As depicted by the lighter shading, air further flows from beneath the main piston 1.45 to the dummy volume inlet valve 1.38.1 which is forced by spring 1.37 onto its outer seat 25 v1.1, thereby holding the valve closed. It is noted that the top of the service main piston stem 1.41 features dummy volume exhaust valve seat v1.2 which is open in its position as shown. The open valve seat v1.2 enables communication between the dummy volume and the dummy exhaust via the hollow bore of service main piston stem 1.41.

29 As previously mentioned, the dummy volume serves as a reference volume for braking operation. With the dummy volume connected to exhaust, the brakes will be released. Air beneath the main piston 1.45 also flows to the inner valve seat v1.9 through the inner bore of the stem of the balancing valve v1.7. The inner valve seat v1.9 is closed 5 because of the lowered position of the main piston 1.45. It will be appreciated that the chamber underneath balancing piston 1.59 communicates with the outer valve seat v1.10 which is shown in the open configuration, because the stem of balancing valve v1.7 is held by the main piston 1.45 against the force of spring 1.61. Thus, the space underneath balancing piston 1.59 communicates with the exhaust 0 port 1.7 via balancing valve choke C1.7. Air beneath main piston 1.45 also flows to the quick service valve 5, in particular to the region above quick service piston 5.104. The auxiliary reservoir is charged from the air below the main piston 1.45 via internal passage 1.21. Additional auxiliary reservoir charging is accomplished by air flow via 5 stability choke C1.3. Thus, it will be understood that the auxiliary reservoir is charged directly by service main piston 1. During charging, it can happen that a pressure differential is created by chokes C1.6 and C1.3 across the main piston 1.45. If, for example, the pressure above the main piston 1.45 exceeds the pressure below the main piston by a predetermined value, then 20 the main piston 1.45 will move downwards into a retarded recharge position (see Figure 16). This results in stem 1.95.1 of the auxiliary reservoir charging valve v1.6 being forced downward, against spring 1.60 so that the disc with the retarded charging choke C1.4 bears against seal ring 1.100 so that charging of the auxiliary reservoir is only permitted through the retarded charging choke C1.4 and choke C1.3. This provides two 25 stages for charging and recharging, dependent on the location of the triple valve in the train consist. Therefore, a more uniform charging throughout the train is accomplished by retarding the charging of the auxiliary reservoir on wagons which are located toward the front of the train.

30 This leads to a faster raise of brake pipe pressure at the rear of the train, which brings about more even brake application, and quicker release, recharge, and subsequent operation of the train. The main piston 1.45 returns to open charging position when brake pipe 12 and auxiliary reservoir pressures approach equalisation. 5 The charging of the accelerated release reservoir 46 takes place via choke C1.5, open valve seat V1.5, and the accelerated release reservoir charging check valve 1.62. The air flows then via pipe bracket 52 (Fig 1) to the accelerated release reservoir 46. 1b. Accelerated release valve (2) In the accelerated release valve 2, both sides of the diaphragm 2.83 are connected to 0 the atmosphere via the exhaust port EX. Accelerated release reservoir air flows to the closed valve seat V2.2 via high sensitivity back flow check valve 2.89 which is held closed by the force of bias spring 2.90 and brake pipe pressure acting against it. Ic. Quick Service Regulating Valve (4) The right side of the diaphragm 4.74 is connected to atmosphere via the quick service 5 chamber QS-CH as explained below in item 1d. The left side of diaphragm 4.74 is pressurised with accelerated release reservoir air. Because the right side of the diaphragm is vented to the atmosphere, the diaphragm 4.74 is forced on its right-hand stop against the force of spring 4.90. Simultaneously, the check valve is forced on valve seat V4.1 by the force of spring 4.91 as a consequence of being linked by valve stem 20 4.2. Thus the quick service regulating valve is closed at this point. id. Quick Service Valve (5) The quick service valve piston 5.104 controls the flow of quick service air to atmosphere. Air in the volume below main piston 1.45 also pressurises the upper area of piston 25 5.104. The piston 5.104 is thereby forced downward (as shown in Figure 12) and opens valve seat V5.1 against the force of spring 5.108. This enables the quick service chamber to vent to atmosphere via the exhaust port 1.7 and exhaust flap 1.75.

31 2. Preliminary Quick Service Configuration Referring to Figure 12, when an application of the brakes is required, this must be initiated by a brake pipe reduction of a minimum predetermined rate. A minimum predetermined rate is required since otherwise small fluctuations in brake pipe pressure 5 (which would occur under normal operating conditions) could cause the brakes to apply inadvertently. The following sequence occurs during "Preliminary Quick Service" stage: 2a. Service Main Piston System (1) and Quick Service Valve (5) The service main piston 1.45 compares brake pipe and auxiliary reservoir pressures acting on equal areas on its upper and lower sides respectively. 0 During brake pipe pressure reduction, the auxiliary reservoir charging check valve 1.5 closes and restricts auxiliary reservoir air flow to the brake pipe via the charging choke C1.6 and through the smaller orifice of the sensitivity choke C1.9. The flow of air from auxiliary reservoir to the brake pipe is also permitted through stability choke C1.3. Thus, the flow of air from auxiliary reservoir to the brake pipe (caused by the reduction in 5 brake pipe pressure) is controlled by sensitivity choke C1.9 and stability choke C1.3. The pressure difference building up across main piston 1.45 moves the main piston 1.45 upward and opens the quick service inlet valve seat V1.3 at a value primarily defined by the spring 1.43. Brake pipe air flows to quick service chamber (QS-CH) via the restricted cross-section between the upper end of the stem of main piston 1.45 and 20 the free flow area of valve seat V1.3. The valve seat V5.1 in the quick service valve remains open so the air from the quick service chamber (QS-CH) is vented to the atmosphere via open valve seat V5.1 and choke C5.1 of the quick service valve. This increases the pressure differential across the main piston 1.45 and accelerates its upward movement. 25 Upward movement of the main piston 1.45 lifts the quick service inlet valve 1.38.2, enabling the quick service pressure to bear against the service main piston stem 1.41 and move it upwardly relative to the spring guide 1.44. The valve seat v1.1 is bearing against dummy volume inlet valve 1.38.1 as best seen in Figure 10. Thus, the passage 32 that previously existed from dummy volume to dummy volume exhaust via valve seat V1.2 is closed. The valve seat V1.1 is still closed at this time. Because the main piston 1.45 has risen, the valve stem in the auxiliary reservoir charging valve v1.6 rises under the force of bias spring 1.60 to close. Thus the charging 5 connection from brake pipe to auxiliary reservoir via valve seat V1.8 is closed. Additionally, again because the main piston 1.45 has risen, valve stem of balancing valve V1.7 also raises closing valve seat V1.10. However, the inner valve seat V1.9 opens and air flows through the centre of valve stem to pressurise the bottom chamber 1.56 underneath the balancing piston 1.59 and the piston 5.104 of the quick service l0 valve 5 with auxiliary reservoir air. The balancing piston 1.59 thus moves upward, bearing against the spring guide 1.67 which acts on the balancing spring 1.69 and introduces a force into the service main piston system 1. 2b. Inshot and Reduction Ensuring Valve (3) Air which entered the quick service chamber QS-CH through quick service inlet valve 15 seat V1.3 flows through choke C3.1, opens the return flow check valve 3.12.2, and passes across open valve seats V3.1 and V3.2 to the left side of the diaphragm 3.74 and on to the dummy volume. The influx of air to the dummy volume is to a predetermined value depending on spring 3.76. This flow of air into the dummy volume from the quick service chamber QS-CH (which is also permitted to exhaust through 20 exhaust chamber 1.7) adds to the reduction of brake pipe pressure which was created by the connection of brake pipe to the quick service chamber. This causes a sudden reduction in brake pipe pressure which is sufficient to send a pressure wave down the length of the brake pipe at a speed close to the speed of sound, triggering downstream valves into operation. This provides a quick response of all the triple valves in the train 25 and reduces in-train forces and slack action which can otherwise cause damage. It also ensures that all triple valves respond to an initial minimum reduction of brake pipe pressure. The Inshot and Reduction ensuring Valve 3 ensures a predetermined minimum dummy volume pressure by connecting quick service chamber to dummy volume 48. This 33 ensures the delivery of sufficient air pressure to the brake cylinder to overcome the brake rigging friction and brake cylinder piston return spring, and provides some braking force. 2c. Quick Service Regulating Valve (4) 5 The quick service regulating valve opens during initial brake application to regulate the brake pipe reduction to a predetermined value during quick service action. Air from the quick service chamber flows to the right side of the metal reinforced diaphragm 4.74 and combined with the force of the spring 4.90 overbalances the force of accelerated release reservoir air on the left hand side, and opens the valve seat V4.1 0 to allow quick service chamber air to exhaust. This exhaust may be choked. Once the air in the quick service chamber reduces to a predetermined pressure level, the accelerated reservoir pressure acting on the left hand side of diaphragm 4.74 overcomes the combined force of spring 4.90 and the quick service air pressure on the right side and closes valve seat V4.1. 5 Thus, the quick service regulating valve's diaphragm 4.74 compares the force of accelerated reservoir pressure against the combined force of quick service chamber pressure and control spring 4.90 over equal areas. Because the accelerated release reservoir pressure stays constant during brake applications, along with the spring force, it provides a fixed reference to ensure that quick service reduction is at the 20 predetermined value. The adopted configuration of the triple valve 40 in Figure 12 is referred to as the "Preliminary Quick Service Configuration". 2d. Surge Suppression Valve (6) During the "Preliminary Quick Service" stage, air from the quick service chamber also 25 flows via quick service inlet valve seat V1.3 to the surge suppression valve 6 to pressurise the area underneath piston check valve V6, pushing it against bias spring 6.1 to close valve seat v6.1. The connecting passage between the brake pipe and the top of 34 main piston 1.45 is closed off for the period of time taken by quick service chamber air to flow through choke C6.0 of the piston V6 and equalise pressure on both sides of piston V6. Thus, during the period of time the valve seat v6.1 is closed, the chamber above main 5 piston 1.45 is isolated from any pressure surges travelling through the brake pipe in the wake of the quick service pressure reduction wave, which can result in a local brake pipe pressure increase on the upper side of main piston 1.45, and in the triple valve being unable to remain in the applied configuration and releasing the brakes. Once the pressure equalises on the opposite sides of piston V6, the piston V6 moves 0 under the force of bias spring 6.1 and re-opens valve seat v6.1, and the connection between the brake pipe and the upper side of main piston 1.45. From this moment on, any further pressure changes in the brake pipe will act on the upper side of main piston 1.45. 3. Service Application Configuration 5 Once the initial quick service activity has ceased, the triple valve changes from the "Preliminary Quick Service" configuration to the "Service Application" configuration as explained below in connection with Figure 13. 3a. Service Main Piston System (1) As shown in Figure 13, piston 5.104 of the quick service valve will be pressurised with 20 auxiliary reservoir air underneath seal 5.100, while above the seal 5.100 is open to atmosphere via exhaust chamber 1.7. Also, the area under seal 5.100 is larger than the area at the top of the quick service piston 5.104. This creates a bias that moves piston 5.104 upward, allowing check valve 5.32 to seal valve seat V5.1 under the force of spring 5.108. Thus, the quick service chamber is isolated from atmosphere but remains 25 connected to the brake pipe pressure via valve seat V1.3. The main piston 1.45, the quick service inlet valve 1.38.2, and the spring guide 1.44 move further upward until the quick service inlet valve 1.38.2 applies force to the service 35 main piston stem 1.41. This results in lifting the dummy volume inlet valve 1.38.1 against the bias spring 1.37, from the valve seat V1.1, opening a flow path from the auxiliary reservoir to dummy volume via application choke and check valve V1.11. Dummy volume air also flows to the left side of diaphragm 3.74 of the inshot and 5 reduction ensuring valve (3), the purpose of which is discussed in item 3b below. As previously explained in connection with Figure 1, the pressure in the dummy volume serves as a reference causing the brakes to apply. During brake applications of less than a full service reduction, air flows from the auxiliary reservoir to the dummy volume until the auxiliary reservoir pressure is reduced to equalise with the brake pipe pressure. 0 Auxiliary reservoir pressure will equalise with dummy volume pressure and brake pipe pressure at approximately a full service brake pipe pressure reduction. The size of the auxiliary reservoir and the size of the dummy volume are designed to provide a pressure equalisation of 350KPa from a regulated brake pipe and auxiliary reservoir pressure (in fully charged condition) of 500KPa. In other words, if the auxiliary reservoir 5 was charged to 500KPa and then connected to the dummy volume which is at atmospheric pressure, the combined auxiliary reservoir and dummy volumes would equalise at 35OKPa. On the Australian railway network the brake pipe is reduced just below this pressure (340KPa) during a full service brake application. The valve stem 1.50 of the balancing valve v1.7 follows the main piston 1.45 by the 20 force of spring 1.53 until it reaches its upper stop. At this point, the inner balancing valve v1.9 remains open retaining the connection between auxiliary reservoir air beneath main piston 1.45 and the bottom chamber 1.56. The balancing piston 1.59 moves to its upper stop under the force of auxiliary reservoir pressure underneath it. This limits the amount of upward bias exerted by balancing piston 1.59 on main piston 1.45. 25 3b. Inshot and Reduction Ensuring Valve (3) As mentioned above, dummy volume air pressurises the left hand side of diaphragm 3.74 and moves it against force of spring 3.76 to the right until it rests against spring guide 3.75. This movement results in closing valve seat V3.2 with check valve 3.12.1 by the force of 30 the spring 3.79 and interrupts the flow between quick service chamber and dummy 36 volume. The return flow check valve 3.12.2 closes the valve seat V3.1 by spring force 3.79 and prevailing pressure. 4. Service Lap Configuration The purpose of the lap position illustrated in Figure 14 is to allow a partial application of 5 the brakes to be held constant. 4a. Service Main Piston System (1) As shown previously, during a service brake application, the dummy volume is charged from the auxiliary reservoir by the service main piston system 1. As soon as the auxiliary reservoir pressure acting below main piston 1.45) is reduced to approximately 0 the value of the brake pipe pressure (acting above main piston 1.45), the service main piston system 1 moves from the elevated service position to the service lap configuration illustrated in Figure 14. In this configuration, valve seat V1.1 is closed and the flow path between auxiliary reservoir and dummy volume is interrupted. The balancing piston 1.59 acts on the balancing spring 1.69 through the spring guide 1.67. 5 This introduces a defined force in the service main piston 1.45, holding it in the service lap position. Thus, the level of brake pipe reduction will determine the volume of air which passes from the auxiliary volume to the dummy volume when in the service application configuration, so that the greater the brake pipe reduction, the greater the reduction of 20 auxiliary reservoir pressure in order to bring about equalisation of their pressures in the service lap configuration. The degree of brake pipe reduction will affect the pressure of the dummy volume detected by the relay valve and will therefore relate to the magnitude of the braking force. Brake pipe and auxiliary reservoir are also continuously connected via the very small 25 stability choke C1.3.

37 The accelerated release reservoir charging choke C1.5 and check valve v1.5 arrangement prevents return flow of accelerated release reservoir air to the brake pipe in the application position. During a further brake pipe reduction, the service main piston system will again move to 5 the service application configuration (Figure 13), and the flow path from auxiliary reservoir to dummy volume will be opened. Subsequently, the same procedure as described above will take place and move the service main piston 1.45 back again to service lap position. The reduction of brake pipe pressure and hence the increase in dummy volume pressure can continue until the auxiliary reservoir pressure is equal to 0 the dummy volume pressure. This will be detected by the relay valve and will correspond to a full application of the brakes. Any further reductions in brake pipe pressure will not affect the pressure level in the dummy volume, but will move the main piston system 1 upward against its stop to isolate the stability choke C1.3 and prevent the flow of auxiliary reservoir air to brake pipe. 5 4b. Inshot and Reduction Ensuring Valve (3) The inshot and reduction ensuring valve 3 assures a predetermined minimum dummy volume pressure. Should the dummy volume pressure drop below this value, due to leakage, for example, the inshot and reduction ensuring valve will open and feed brake pipe pressure via the quick service chamber to the dummy volume (see Figure 12). 20 5. Release from Service Configuration To release the brakes, the brake pipe pressure has to be increased by a predetermined margin above the level of the auxiliary reservoir pressure at each triple valve. The complete release sequence is illustrated by Figures 15 and 16. 5a. Service Main Piston System 1 25 The increase of brake pipe pressure results in a pressure differential across main piston 1.45. The resulting force acts against the force of balancing spring 1.69, and at a predetermined pressure difference, the main piston 1.45 moves downwards until it contacts balancing valve stem 1.50.

38 The service main piston stem 1.41 remains in the service lap position under the action of the quick service pressure, while spring guide 1.44 and quick service inlet valve 1.38.2 follow the main piston 1.45 under the force of spring 1.43. The valve seat V1.2 of the dummy volume exhaust valve is closed during this release stage. 5 Further downward movement of the main piston 1.45 closes inner valve seat V1.9 and opens outer valve seat V1.10 of the balancing valve through valve stem 1.50. Accordingly, auxiliary reservoir air in the bottom chamber 1.56 under the balancing piston 1.59 and under the piston 5.104 of the quick service valve 5 starts to vent to atmosphere via choke C1.7. The main piston 1.45 moves further into the release 0 position as a result of pressure reduction in the bottom chamber 1.56 under the balancing piston 1.59. 6. Accelerated Release and Retarded Recharge As discussed below under "Accelerated Release Valve 2", the accelerated release valve 2 is triggered during the release stage of a service application. When triggered, the 5 accelerated release reservoir air passes into the brake pipe creating a locally amplified release wave which passes rapidly through the train. 6a. Service Main Piston System 1 and Quick Service Valve 5 During further downward travel of the service main piston 1.45, the following functions are performed: 20 As the air in the bottom chamber 1.56 beneath the balancing piston is now connected to the atmosphere, the balancing piston 1.59 will move downward towards its lower stop. The connection between dummy volume and dummy volume exhaust opens after main piston stem 1.41 moves down under the action of spring guide 1.44, and valve 1.38.2 closes valve seat V1.3, interrupting the flow path from brake pipe to quick service 25 chamber thereby removing the effect of quick service air on the stem 1.41. Dummy volume pressure is vented through open valve seat V1.2 (see Figure 16) and via the release choke C1.8 to atmosphere. Subsequently, the charging connection from brake 39 pipe to auxiliary reservoir through valve V1.8 is opened by the lowering of valve stem 1.95.1. As soon as the auxiliary reservoir air under piston 5.104 has been vented to atmosphere via choke C1.7, the quick service valve piston 5.104 opens the flow path for 5 quick service chamber air to exhaust to atmosphere, via valve seat V5.1 and choke C5.1. As long as the pressure differential between brake pipe and auxiliary reservoir across the main piston 1.45 exceeds the forces of the combined three springs: balancing spring 1.69; charging valve spring 1.60; and balancing valve spring 1.61, the service main 0 piston system is locked to its lower stop in the retarded recharge position of Figure 16. This allows the valve stem 1.95.1 to seat on the sealing ring 1.100, and charging of the auxiliary reservoir is now performed via choke C1.6 and the retarded charging choke C1.4. This leads to more uniform charging throughout the length of the train as explained previously. When the pressure difference drops, the service main piston 5 moves back to the charging lap position (see Figure 10), and only choke C1.6 determines the further charging time. 6b. Accelerated Release Valve (2) The accelerated release valve 2 has a diaphragm piston with dummy volume exhaust pressure acting on both sides of the metal reinforced rubber diaphragm 2.83. Timing 20 choke 2.84 controls the flow of air and pressure build up on the left hand side of diaphragm 2.83. The operation of the accelerated release valve is independent of the operation of the main piston 1.45. The accelerated release valve is triggered by dummy volume air that is retained by choke C1.8 when the dummy volume is connected to dummy volume 25 exhaust. The dummy volume air flows unrestricted to the right hand side of the diaphragm 2.83 (but not to the left hand side which is choked by timing choke 2.84) and overcomes the force of the spring 2.87, moving diaphragm 2.83 to its left stop and lifting check valve 2.38 from valve seat V2.2. Thus, a flow path is established from the accelerated release reservoir to the brake pipe via backflow check valve 2.89 and valve 40 seat V2.1. This flow path remains open until the brake pipe and accelerated release reservoir pressures have nearly equalised. Then the backflow check valve 2.89 closes the valve seat V2.1. The effect of accelerated release reservoir air feeding back into the brake pipe 12 is to 5 amplify the release impulse which passes rapidly throughout the train. It will be understood that the accelerated release valve 2 is not opened until the release of the dummy air to the dummy exhaust DV and thus the pressure of the accelerated release volume is substantially constant throughout braking. When the restricted flow of dummy volume on the left hand side of diaphragm 2.83 and 0 the force of spring 2.87 overbalance the force on the right hand side of the diaphragm 2.83, the diaphragm 2.83 moves back to its right hand stop position closing the valve seat V2.2. 7. Emergency Application Configuration 7a. Service Main Piston System 1 5 The service main piston operates during an emergency application in general as described in figures 12 and 13. However, deviating from above, the main piston 1.46 is forced against its upper stop by auxiliary reservoir pressure, because brake pipe pressure is completely vented as shown in Figure 17. The stability choke C1.3 is closed, also closing the connection 20 between the auxiliary reservoir and the brake pipe. A constant connection between auxiliary reservoir and dummy volume remains open via valve seat V1.1.

Claims (18)

1. A fluid pressure brake unit for use in a chain of like units, the unit comprising: a fluid port for connection to a brake pipe for providing a source of fluid to the unit at a first brake pipe pressure; 5 fluid ports for connection to a plurality of fluid reservoirs or volumes, the unit operable to effect charging and discharging of the reservoirs with fluid, the plurality of reservoirs also including an auxiliary reservoir; a main piston subjected to opposing pressures of brake pipe and auxiliary reservoir, whereby on a predetermined reduction of brake pipe pressure below the first brake pipe 10 pressure on a first side of the piston, the unit is operatable to effect brake application; a quick service feature operable upon said predetermined reduction of brake pipe pressure to effect a quick service reduction, being a sudden local reduction of pressure on said first side of the main piston to affect other units in the chain; and a quick service regulator operable to ensure the quick service reduction is within a 15 predetermined pressure range below the first brake pipe pressure; wherein the quick service feature includes a quick service chamber, whereby, upon the predetermined reduction of brake pipe pressure on said first side of the piston, the unit is operable to open a connection between the first side of the piston and the quick service chamber and to connect the quick service chamber to atmosphere via a non-choked 20 exhaust.

2. The fluid pressure brake unit as claimed in claim 1 wherein the predetermined pressure range for quick service reduction is in the range of about 15 to 17kPa.

3. The fluid pressure brake unit as claimed in claim 1 wherein the quick service reduction is about 15kPa. 25

4. The fluid pressure brake unit as claimed in any one of the preceding claims wherein at least one of the reservoirs serves as a reference reservoir maintaining a substantially constant pressure during brake application and wherein the quick service regulator ensures 42 that the quick service reduction drops the pressure locally on the first side of the main piston to a predefined pressure range below that of the reference reservoir.

5. The fluid pressure brake unit as claimed in any one of the preceding claims wherein the quick service regulator exhausts the quick service chamber to atmosphere via the non 5 choked exhaust.

6. The fluid pressure brake unit as claimed in claim 5 wherein the quick service regulator compares the pressure in the quick service chamber with that of the reference reservoir.

7. The fluid pressure brake unit as claimed in claim 6 wherein the pressures of the 10 quick service chamber and the reference reservoir act on opposite sides of a diaphragm valve having a diaphragm.

8. The fluid pressure brake unit as claimed in claim 7 wherein the quick service chamber pressure and a biasing means act on one side of the diaphragm with the pressure of the reference reservoir acting on the other side of the diaphragm. 15

9. The fluid pressure brake unit as claimed in claim 8 wherein the unit is operable such that when the combined effect of the quick service chamber pressure and the biasing means exceeds that of the reference reservoir, the diaphragm valve is operable to exhaust the quick service chamber to atmosphere, until the quick service chamber pressure and the biasing means force equalise with or drop below the reference reservoir pressure. 20

10. The fluid pressure brake unit as claimed in any one of claims 1 to 4 wherein the unit further includes a surge suppressor responsive to operation of the quick service feature, to isolate the first side of the main piston from the brake pipe for a predetermined period of time.

11. The fluid pressure brake unit as claimed in any one of claims 5 to 9 wherein the unit 25 includes a surge suppressor including a piston, responsive on one side thereof to pressure in the quick service chamber to close a connection between the brake pipe and the first side of the main piston, the piston having a choked passage from said one side to the other, to provide for equalisation of the pressure on both sides of the piston to permit opening of the connection between the brake pipe and the first side of the main piston. 43

12. The fluid pressure brake unit as claimed in claim 10 or 11 wherein the surge suppressor is operable to close the connection between the brake pipe and the first side of the main piston for approximately 2 seconds.

13. The fluid pressure brake unit as claimed in any one of the preceding claims wherein 5 the fluid pressure brake unit comprises a triple valve for a braking system on a railway wagon or a tandem of railway wagons.

14. The fluid pressure brake unit as claimed in any one of claims 4 to 13 dependent upon claim 4 wherein the reference reservoir is an accelerated release reservoir for creating a release impulse on brake release. 10

15. The fluid pressure brake unit as claimed in any one of claims 4 to 13 dependent upon claim 4 wherein the reference reservoir comprises an emergency reservoir/volume.

16. The fluid pressure brake unit as claimed in any one of claims 4 to 13 dependent upon claim 4 wherein the reference reservoir comprises a control reservoir.

17. The fluid pressure brake unit as claimed in claim 5 wherein the quick service feature 15 also exhausts the quick service chamber to atmosphere via a second exhaust.

18. The fluid pressure brake unit as claimed in claim 17 wherein the second exhaust is choked.