Patent GB-190518-A (GB)
Title: Improvements in or relating to railway vehicle braking systems
IPC: B60T13/46
Filed: 1921-08-26
Abstract: 190,518. Glascodine, R. T., McDermid, W. F., and Spencer, A. Aug. 26, 1921. Fluid - pressure. - Relates to improvements in railway vehicle brake systems comprising a vacuum train pipe and vacuum brake apparatus and a " Westinghouse " train pipe and elements of " Westinghouse " brake apparatus, the vacuum brake cylinder functioning also as a " Westinghouse " brake cylinder so that the brakes of a vehicle fitted with the system may be operated upon the " Westing- house " system or upon the vacuum system. The triple valve 1, auxiliary reservoir 2, and train pipe 3 of the pressure system and the train pipe 8 of the vacuum system are connected to the ballvalve fitting 4 of the usual vacuum cylinder 5. Stopcocks 6, 7 are provided for cutting out the system not in use, or a three-way valve may be fitted at 9. Means are provided for preventing the ball-valve of the fitting 4 being unseated when used for normal pressure working. As shown in Fig. 2, this may be effected by arranging a spring 15 behind the diaphragm 13 of the device 14 by which the ball 11 is unseated when the handrelease lever 10 is operated. The valve performs the usual functions when the system is working under vacuum, and functions as a pressure relieving and hand releasing valve when working under pressure. In a modification, the dia. phragm 13 is dispensed with, the stem of the trip member 14 being packed by a rolling rubber ring where it passes out of the valve fitting. Fig. 4 shows an arrangement in which the trip member stem 17 is acted upon by the stem 26 of a diaphragm piston 22, the piston chamber 23 being connected at 24 to the pipe 25, Fig. 1. In a modification, the stem 17 may be locked, to prevent unseating of the valve under pressure, by a hand-operated cam on a cross-shaft. A valve box may be arranged between the ballvalve fitting 4 and the brake cylinder so as to control the passages 20, 21 In one position of this valve, the cylinder is connected with the fitting 4 for normal vacuum working; in the other position the cylinder is connected with the pressure train pipe and the atmosphere. The conversion from vacuum to pressure working may be effected by hand or automatically. Fig. 8 shows an automatic valve for the purpose. The valve housing 40 contains ports 51 controlled by a piston 49 the rod 46 of which has two diaphragms 44, 45. The diaphragm 41 is open to atmosphere at the top and the space below the diaphragm 45 is connected to the pressure train pipe at 47. The housing has a connection 41 to the vacuum train pipe, a port 43 leading to the pressure train pipe, and a connection 42 to the brake cylinder. When the pressure train pipe is not in use, and vacuum is formed in the vacuum train pipe, the valve piston 49 falls intothe position shown, thus opening the brake cylinder to the vacuum pipe. When the vacuum train pipe is not in use, the piston moves up and the brake cylinder connection is opened to the pressure train pipe. In a modification, a spring is used instead of the diaphragm 45 and trainpipe connection 47. The piston rod packing 54 is arranged to withstand both pressure and vacuum. Invacuum brake installationsfitted with independent vacuum reservoirs, the reservoirs may be used as the compressed air reservoirs when working as a pressure system.