Patent GB-615028-A (GB)
Title: Improvements in electropneumatic braking apparatus for railway vehicles and the like
IPC: B60T13/66
Filed: 1946-08-16
Abstract: 615,028. Fluid-pressure-operated brakes. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. Aug. 16, 1946, No. 24380. Convention date, May 20, 1942. [Class 103 (i)] In an electrically-controlled automatic compressed air brake system comprising on a driver's vehicle of a train, a brake-pipe equalizing discharge valve and reservoir controlled by a driver's self-lapping valve and pneumatically operated switches also controlled by the driver's valve and controlling application and release magnet valves on each vehicle, the application switch is connected to the equalizing reservoir so that an application is effected by the simultaneous venting of the brake-pipe by the discharge valve and the applicaton magnet valves. The equipment on each vehicle comprises a brake cylinder 5, auxiliary reservoir 6 and a triple valve 3, a magnet application valve 1 which vents the brake-pipe 71 and a magnet release valve 2 which controls the triple valve exhaust. A driver's selflapping valve 45 controls pneumatic switches S1, S2 for the valves 1, 2, a switch S3 in series with the switches S1, S2, a brake-pipe equalizing discharge valve D and a charging valve device C. The main reservoir 11 is directly connected to the lower chambers of the switches S1, S2, S3. Normally, valves 23, 24 of the valve device C are held respectively open and closed by a spring 26 acting on a piston 27 so that air from the main reservoir 11 feeds through a reducing-valve 12, valve 23 and non-return valve 28, to the chamber 29 of the discharge valve D, to the equalizing reservoir 8, to the piston chamber 57 of application switch S1 to the inlet 77 of the driver's valve 45 and to the brake-pipe 71 and the lower chamber of valve D through a non-return valve 69. Brake-pipe pressure equalizes past the piston 58 of switch S1 to a reservoir 7 and valve 59 being thus closed and chamber of piston 64 being vented by port 60, the piston 64 opens valve 62 to vent by port 61 the chamber of a spring- urged piston 66 which thus opens the contacts 68 of the circuit of the application valves 1. The pipe 72 leading from the driver's valve is normally at atmospheric pressure and is connected to the chambers 33, 47 of switches S2, S3 and through non-return valve 46 to a reservoir 9 and chamber 35 of switch S2. The chamber of piston 37 being vented by port 36, this piston holds open valve 40 to vent the chamber of piston 42 by port 39, thus closing the contacts 44 of the circuit of the release valves 2. Similarly, the piston 49 normally opens valve 51 to vent chamber of piston 53 by port 48, thus opening contacts 55 of switch S3 to break the circuit of the valves 2 which are thus opened. The driver's valve 45 when operated to apply the brakes supplies air from the reservoir 8 by pipes 77, 72 to chambers 17, 13 of charging valve C and to reservoir 9, but as the pressure rises more rapidly in chamber 17, the piston 14 moves down to connect chamber 17 to chamber 78 of piston 22, whereby valve 19 is closed and valve 18 opened to connect the left-hand chamber of piston 27 to the main reservoir 11. The valve 24 is thus opened to vent the right-hand chamber of the piston by port 25 and to close valve 23, thus cutting off the reservoir 11 from the system. Air from the driver's valve 45 is also supplied by pipe 72 to the chamber 47 of the switch S3, causing piston 49 to close valve 51 and open valve 52 to admit air from main reservoir 11 to chamber of piston 53, thus closing contacts 55. The circuit of the release valves 2 is thus closed since the contacts 44 of switch S2 also remain closed. The fall of pressure in reservoir 8 and in chamber 29 of discharge valve D, due to the connection with reservoir 9 opens the valve 31 to vent the brake-pipe 71. The pressure fall in chamber 57 of application switch S1, also connected to reservoir 8, opens valve 59 to connect reservoir 7 and the lower chamber of piston 58 to chamber of piston 64 which is thus depressed to close valve 62 and open valve 63 to admit air from main reservoir 11 to chamber of piston 66, thus closing contacts 68 and the circuit of the application valves 1. The brake-pipe being thus vented by the valves 1 as well as by the valve D, the triple valves 3 are operated to supply the brake cylinders 5. When the brake pipe pressure has equalized with the pressure in chamber 29 in valve D, as determined by the position of the handle of the driver's valve, the valve 31 closes and when the pressure in reservoir 7 of switch S1, by escape through port 60, has equalized with the pressure in chamber 57, the valve 59 closes and the piston 64 returns to effect the reopening of contacts 68 and thus the re-closing of the application valves 1. The triple valves then return to lap position. If the driver's valve handle is partly returned, the pressure in chamber 17 of charging valve C is reduced through pipes 79,'72, the piston 14 moves up to vent chamber 78 through port 16, the piston 22 is depressed by its spring to close valve 18 and open valve 19, thereby venting chamber of piston 27 which returns to close valve 24 and open valve 23. The brake-pipe 71, reservoir 8 and the chambers connected thereto are thus recharged and the triple valves are returned to the release position. The pressure in chamber 33 of release switch S2 is also reduced by the driver's valve causing piston 34 to open valve 35, thus connecting reservoir 9 to chamber of piston 37 which then closes valve 40 and opens valve 41 to admit air from main reservoir 11 to chamber of piston 42. The contacts 44 are thus opened to de-energize the valves 2 to permit exhaust of the brake cylinders 5 through the triple valves. When the pressure in reservoir 9 has equalized, by exhaust through port 36, with that in chamber 33 as determined by the position of the driver's valve handle, the piston 34 re-closes valve 35 and the piston 37 returns to effect the re-closing of contacts 44. The valves 2 are thus closed and the brake cylinder exhaust ceases. Specification 434,131 is referred to.