Patent GB-990074-A (GB)
IPC: B60T15/54
Abstract: 990,074. Pressure release valves in braking systems. COMPAGNIE DES FREINS ET SIGNAUX WESTINGHOUSE. June 18, 1962 [June 20, 1961], No. 23352/62. Heading F2F. A release valve VP for a distributer D in a fluid-pressure operated braking system having ports 2, 3, 4, 5 connected to a train brakepipe, a distributer brake-pipe and to auxiliark RA and control RC reservoirs respectively includes manually-operated multiple valves 8, 9 for opening the reservoirs RA and RC to the atmosphere, also switching control means which normally permit pressure to pass from the train brake-pipe to a brake-pipe chamber of the distributer D but, when the train brakepipe is vented to the atmosphere, the control is moved by pressure from the reservoirs RA and RC to connect the said brake-pipe chamber to the control reservoir RC and to seal it from the train brake-pipe, whereby the brake cylinder is vented to atmosphere and caused to release. The switching control means has a piston 23 having its upper face always exposed to train brake-pipe pressure by way of passage 24 and chamber 20 and its lower face exposed to atmospheric pressure by way of .a port 12. The piston 23 is fixed to the stem of a valve 22 which can seat at 21 to close the connection between the train brake-pipe from the distributer. The valve stem carries a ported sleeve 31 whereby the control reservoir inlet 9 is connected to the outlet 3 to the distributer when the valve 22 is seated as in Fig. 5. The distributer (see Fig. 8) includes a main device 35, an initial charging device 36, a control device 37, a lap device 38, an initial application device 39 an acceleration device 40 and a valve 41 for charging the auxiliary reservoir, all of conventional construction. With the relief valve in the position shown in Fig. 1, when the drivers' brake is operated normally it connects the train brake-pipe CGT to the main reservoir RP or to atmosphere to apply or release the brake. In the latter case the brake cylinder CF will be evacuated by way of passage 43, the bore 44 of the sleeve 45 of the main distributer device and the passages 46 and 47 to a port 48 open to the atmosphere. If it is wished to eliminate an overcharge of the reservoirs RA and RC when the train brake-pipe is under pressure as in Fig. 1, the handle 17 is tilted sideways manually to open valves 8 and 9 (see left-hand side only of Fig. 5). If the vehicle is uncoupled and it is wished to empty the brake cylinder CF without emptying the reservoirs RA and RC, the handle 17 is tilted momentarily, whereby the pressure below the piston is raised, lifting it against the atmospheric pressure in the chamber 20 so as to close the valve 22. In this position the passages in the sleeve 31 connect the reservoir RC to the distributer which in consequence empties the brake cylinder in the manner previously described. The connection set up in this instance between the auxiliary and control reservoirs by way of the sleeve 31, the charging valve 41 of the distributer cause pressure from the control cylinder to recharge the auxiliary reservoir. In this operation the auxiliary and control reservoirs will only be emptied if the handle 17 is operated for a long period. The valve 22 is reset automatically when pressure is re-established in the train brake-pipe.