Patent GB-403794-A (GB)
Title: Control valve for compressed air brakes
IPC: B60T15/30
Filed: 1932-11-15
Abstract: 403,794. Fluid-pressure brakes. COMPAGNIE GENERALE D'ELECTRICITE, 54, Rue La Boetie, Paris. Nov. 15, 1932, No. 32265. Convention date, Nov. 28, 1931. [Class 103 (i).] Distributing valve for compressed air brakes adapted to give graduated application and release comprises pistons 3, 12 operating slide valves 11, 10 under the influence of train pipe pressure in chamber 2, auxiliary reservoir pressure in slide valve chamber 7 and the pressure of a control reservoir 20. The brake cylinder 66 is supplied in two stages by a valve 94 and a load cylinder 69 may be brought into action in the second or slow charging stage. Exhaust from the brake cylinder is controlled by a valve 95 controlled by brake cylinder and auxiliary reservoir pressure. In release position, piston 12 is held to the left by a spring 15 in its interior, abutting against fixed pins 14. On fall of train pipe pressure when the brakes are applied, piston 3 first moves slide valve 11 to the right as far as a bolt 21 connecting pistons 3, 12 allows and the train pipe is connected by a passage 33 to an accelerating chamber 39. Further movement to the right moves the piston 12 by the bolt 21 until it rests on a seat 97 and the auxiliary reservoir 9 is connected to the brake cylinder 66 by passages 24, 23, the valve 94 and passage 46. The train pipe and the chamber 39 are still connected by a passage 34 in the slide valve 10. The fall in pressure in the valve chamber 7 causes piston 12 to be forced firmly on the seat 97. In a graduated application when the pressure in chamber 7 falls slightly below train pipe pressure piston 3 moves to the left to neutral position until its rod abuts against the contact plate of a spring 16 in the piston 12 closing the brake cylinder supply. This cycle is repeated until the brakes are fully applied. On increase of train pipe pressure to release the brakes the piston 3 moves to compress spring 16 and connects the brake cylinder to exhaust through passages 29, 27, 28, 25, 26 and valve 95, and reservoir 9 is supplied through passages 4, 6 until, in graduated release, its pressure is equal to that of the train pipe, when spring 16 moves the piston 3 and the valve 10 back to neutral position to close these connections. The piston 3 may be moved from neutral position to further supply or release the brake by variation of train pipe pressure. At final release the piston 12 is moved to the left by spring 15 and the valves take up the position shown, the brake cylinder now exhausting through the passages 30, 31, the accelerating chamber through passages 35, 33, 32, 31 and the reservoirs 9, 20 being charged through calibrated nozzles 5, 18. Cock 92 is turned to connect, load brake cylinder 69 which is supplied from passage 46 by channel 52 in piston 51 of valve 94 when the piston of this valve falls to restrict the supply to cylinder 66 by closing valve 43, leaving open only the calibrated nozzle 45. Final release from cylinder 69 takes place through passages 55, 56 when piston 51 rises. Piston 51 is locked in the lower position against an elastic disc 60 which compensates for the play in the locking system by spring-pressed balls 57 engaging a coned part of the stem of the piston. When cock 92 is turned to bring the load cylinder 69 into operation it also opens an additional passage through a calibrated nozzle 64 to the brake cylinders to increase the supply thereto. The exhaust of the brake cylinders through valve 95 and outlet 78 is controlled by auxiliary reservoir pressure acting on diaphragm 71 through passage 70 and the pressure of the exhaust air in chamber 83 acting below the diaphragm and on a piston valve 75, also by springs 73, 79 normally holding the diaphragm and piston respectively in raised position. Exhaust takes place when brake cylinder pressure is sufficiently high to compress the spring 79 or when auxiliary reservoir pressure is sufficiently high to compress springs 73 and 79. The accelerating chamber comprises two chambers 39, 42 connected by a valve 41 and a calibrated opening 40.