GB913428A - Improvements in or relating to vacuum brake installations for rail vehicles - Google Patents

Abstract

913,428. Vacuum - braking apparatus. KNORR-BREMSE G.m.b.H. May 22, 1959 [Aug. 2, 1958], No. 17521/59. Class 103 (1). In a vacuum-brake installation for rail vehicles of the kind in which a brake cylinder 17 has vacuum maintained in its first (15) and second (39) chambers when the brakes are released by means of a first control device in the form of a non-return valve 45 when the brakes are released and vacuum is reduced in the first chamber 15 and maintained in the second chamber 39 so that the brake cylinder piston moves upwardly to apply the brakes, a second control device 47 is provided such that when a balance of pressure has been produced between the first chamber 15 and the second chamber 37, a pipe is opened to connect the first chamber 15 to the train pipe 1, the second control device 47 being also adapted to close the pipe connecting the first chamber 15 to the train pipe when an excess pressure prevails in the latter chamber. When the brake is released, vacuum of regulating level is present in the train pipe 1, the piston chamber 5, the return control chamber 11 of the control valve 7, the vacuum reservoir 41, the two brake cylinder chambers 39, 15, and on both sides of the diaphragm 49 of the second control device 47. The valves 25 and 35 of the control valve 7 are closed and the cut-off valve 53 of the second control device is open. When air is admitted to the train pipe 1, the pressure in piston chamber 5 increases, the piston 9 descends and the piston-rod 19 opens valve 25 so that air from the valve chamber 23 enters the return control chamber 11 and the first brake cylinder chamber 15. At the same time, the pressure prevailing below the diaphragm 49 is increased from the train pipe 1 and the cut-off valve 53 closes so that the branch pipe line 51 is interrupted. As soon as pressure equality prevails on both sides of the piston 9, spring 21 closes the valve 25 and the first brake stage has been reached. In the case of stepped release of the brake, the pressure in the train pipe 1 is reduced by a slight amount, the piston 9 therefore ascends and opens the valve 35, so that air from the first brake cylinder chamber 15 passes via the valve chamber 31, to space 27 and non-return valve 37 into the second brake cylinder chamber 39 and the vacuum reservoir 41. A drop in pressure thereby occurs in the return control chamber 11 and as soon as pressure equality prevails on both sides of the piston 9, the valve 35 closes again. In the case of full release, the valve 35 remains open until termination of the release process, complete pressure equalization occurs, therefore between the two brake cylinder chambers 15 and 39. As soon as this is attained the valve 53 opens, whereby air is aspirated from the first brake cylinder chamber 15 and via the non-return valve 45 also from the second brake cylinder chamber 39 and the vacuum reservoir 41 into the train pipe 1 until the regulating vacuum has been reached again. The non-return valve 37 prevents direct aspiration from the second brake cylinder chamber 39. When regulating vacuum is reached in the return control chamber 11 the piston 9 descends and the valve 35 closes. The release valve 43 is provided for destroying vacuum in the reservoir 41 when a vehicle is uncoupled.