Patent GB-356725-A (GB)
Title: Improvements relating to fluid pressure braking apparatus
IPC: B60T15/30
Filed: 1930-05-28
Abstract: 356,725. Fluid - pressure bra k e s. TOMLINSON, A. V., 65, Victoria Street, London.-(Westinghouse Brake Co. of Australasia, Ltd. ; George Street, Concord West, New South Wales, Australia.) May 28, 1930, No. 16475. [Class 103 (i).] In a fluid-pressure brake comprising a triple valve the fluid vented to an accelerating bulb from the train-pipe is subsequently supplied to a valve device for effecting any desired action or control in connection with the operation of the brakes other than effecting the release of fluid from the bulb itself. This valve device may effect local venting of the train pipe or control the supply of fluid to the brake cylinder. In an apparatus comprising a triple valve controlled by train pipe and auxiliary or other reservoir pressure, when releasing the brakes, the auxiliary reservoir may be temporarily connected with the atmosphere to enable train-pipe pressure more readily to move the triple valve to its release position. This temporary connection may be effected by the valve device operated by fluid from the accelerating bulb. In the apparatus shown in Fig. 1 in service application fluid is vented from the train pipe 6 by the triple-valve slide valve 1 to the accelerating bulb 9, this fluid raises a piston 32 of a quick-action valve C against train-pipe pressure in a chamber 33 and escapes by a port 89 in the slide valve 29 of this valve and by restricted apertures 35, 37 to atmosphere. The rate of flow through the aperture 37 is the same as the reduction of train-pipe pressure. In an emergency application the considerable fall in train-pipe pressure in chamber 33 allows the piston 32 to raise the spring stop 85 and move the slide valve 29 to uncover a passage 86, by which the fluid from the accelerating bulb passes to a vent valve D, a piston 41 of which it operates to open a valve 39 and vent the train pipe 6 to an atmospheric port 40 which may be connected to a closed vessel or the brake cylinder. The fluid beneath the piston 40 gradually escapes through ports 87, 43 to atmosphere and the valve recloses. The reduction in pressure in bulb 9 causes the piston 32 to return and ports 89, 35 to register and vent the bulb 9 to atmosphere whereupon the piston 32 returns to the position shown. The train pipe and bulbs 9, 10 may be connected by the movement of the graduating valve 2 on brake application. In the apparatus shown brake-cylinder pressure is controlled by a relay valve B adapted to supply fluid from the service reservoir 28 to the brake cylinder 17 by means of a valve 26 controlled by a differential piston 19 operated by fluid supplied to the chamber 20 below it from the auxiliary reservoir 13 and triple valve chamber 3 by the triple valve when moved to brake application position. Brake-cylinder pressure acting above the piston recloses the valve 26 to obtain a lap position. Graduated application is thus obtained as the pressure supplied to the chamber 20 is graduated by the triple valve. Graduated release is similarly obtained by means of the slide valve 15 operated by the piston 19, adapted to connect the brake cylinder to exhaust passage 24. The supply of fluid to and from the chamber 20 is controlled by the triple valve. When on a brake application train-pipe pressure in the piston chamber 5 of the triple valve falls the graduated valve 2 is first moved to close the connections to the service, supplementary, and the auxiliary reservoirs and then to close the chamber 20 from the exhaust passage 24. The main slide valve 1 is then moved and the cavity 62 therein which normally connects the bulb 9 to the exhaust passage 24. connects the bulb 9 and the auxiliary bulb 10 by means of passage 77, to a passage 48 through a ball valve 47 to the train pipe. When the piston 4 engages the spring stop 82 the auxiliary reservoir 13 and chamber 3 are connected by the port 72, which has been uncovered by the graduating valve 2, to the passage 67 and the chamber 20 of the relay valve 16. The consequent fall of pressure in the chamber 3 causes the piston 4 to move the graduating valve to cover the port 72 and thus obtain a lap position. Increase of train-pipe pressure to release the brakes returns the triple valve to the position shown and connects the relay valve chamber 20 by a cavity 69 to the exhaust cavity 24. Also fluid is supplied from the supply reservoir 11 through passages 54, 57 to the chamber 3 and moves the piston 4 up to reclose the port 57 and to interrupt the release of fluid from the chamber 20. By this means a graduated release is obtained. On an emergency brake application the piston 4 displaces the stop 82 and the chamber 3 and auxiliary reservoir are connected to the chamber 20 by a passage 83 and a port 84, which is not controlled by the graduating valve so that the pressure in the auxiliary reservoir and the chamber 20 will equalize and maintain the piston up and the valve 6 open to supply full brake pressure. When train-pipe pressure is restored to release the brakes after an emergency application the graduating valve 2 is first moved to uncover the port 57 and the slide valve 1 then moves to connect this passage to port 78 and the bulb 9 in order to vent the chamber 3 and auxiliary reservoir 13 and facilitate the movement of the triple valve to release position. The auxiliary reservoir may however be vented to another closed receptacle or the atmosphere or the fluid vented to the bulb 9 may be used to bring about this function by means of a valve such as the vent valve D. The fluid in the accelerating bulb may also be supplied to operate a valve device in a service application by the further movement of the main or graduating slide valve of the triple valve. A dummy brake cylinder 12 having a piston 44 moving against a spring 45 is connected by a cavity 65 in the valve 1 to the passage 67 through which the chamber 20 is supplied. This increases the capacity of the chamber 20 by the movement of the piston 44 corresponding to the increase of volume of the brake cylinder 17 due to the movement of the brake piston. To maintain the valve 2 in close engagement with the valve 1, cavity 119 is provided leading to an atmospheric port in release position. In Fig. 2 the fluid vented to the accelerating bulb is used to control the supply to the brake cylinder. The triple-valve slide valve con. nects the train-pipe chamber 5 to the accelerating bulb 9 first by movement of the graduating valve 2 and a restricted port 106 then.by movement of the main valve 1 and a port 105. Fluid from the bulb 9 leaks to a bulb 10 and acts on a diaphragm 114 to close a valve 111 through which fluid is being supplied to the brake cylinder, this supply being maintained by a restricted port 113. Brakecylinder pressure when it attains a certain value reopens the valve 111. Reduction of pressure in the triple valve chamber 3 by flow to the brake cylinder through the port 102 causes the piston 4 and the valve 2 to move to lap position and cover this port. In a modification port 106 may lead to a cavity 104 so that fluid is initially vented from the train pipe to atmosphere by ports 93 past the valve 111 to brake-cylinder passage 18 which is still connected to exhaust by the slide valve 1. The auxiliary reservoir is supplied on charging through passages 101, 107, and the triple valve chamber 3 and the bulbs 9, 10 are exhausted through passages 97, 96, 104, and brake-cylinder passage 18. Return flow from bulb 9 to the train pipe in service position of the valve is prevented by a ball valve 100.