Patent GB-343929-A (GB)
Title: Improvements relating to fluid pressure braking apparatus
IPC: B60T15/18
Filed: 1929-11-25
Abstract: 343,929. Fluid-pressure brakes. TOMLINSON, A. V., 65, Victoria Street, London.- (Compagnie des Freins Westing- house ; 23, Rue d'Athenes, Paris.) Nov. 25, 1929, No. 36070. [Class 103 (i).] In graduated release valves for use with the usual triple valve and of the kind controlled by brake cylinder and auxiliary reservoir pressures acting against a constant pressure the release valve element is given a further movement from the graduated release position when the brake cylinder pressure has fallen to a low value to effect the complete release of the brakes. The release valve also controls the passage by which the auxiliary reservoir is charged from the train-pipe through the triple valve. The apparatus includes the usual triple valve 3 and the graduated release valve device 4 comprising diaphragms 5, 27 connected by a rod operating the valve 13. The diaphragm 27 is capable of movement within a box 24 secured to a diaphragm 6 the upper and lower chambers of the box being open respectively to the valve chamber 12 and to the atmosphere through passages 28, 29. The underside of the box is secured to a diaphragm 7. In normal conditions the diaphragms are in the fully raised position in which the valve cavity 15 connects the exhaust port 33 of the triple valve by passages 32, 31 to an exhaust passage 30 thus connecting the brake cylinder to atmosphere. The passage 35 leading from the triple valve chamber 21 and thus from the train-pipe 37 and also the passage 34 leading from the constant pressure reservoir 1 are uncovered. The chamber 12 is permanently connected to the auxiliary reservoir 17 and the chamber 22 to the reservoir 1. These chambers and reservoirs are thus all maintained at train-pipe pressure. The upper chamber 8 is permanently open to the brake cylinder 9 through the passage 11. When an application of the brakes is effected the triple valve 3 operates in the usual way to supply the brake cylinder the pressure in which causes the diaphragms 5, 27 to move downwardly to the extent permitted by the box 24 thereby closing the passage 34 to isolate the reservoir 1 from the chamber 12 and cutting off the passage 31 from the passage 30. If the train-pipe pressure is now raised air is supplied to the chamber 12 and the auxiliary reservoir through the passage 35 and acting on the diaphragm 6 causes further downward movement of the valve 13 to connect the passages 30, 31 by the cavity 14 while at the same time the passage 35 is closed cutting off the supply to chamber 12. The fall of pressure in the brake cylinder and chamber 8 causes a return movement of the valve to release position. This alternate exhausting of the brake cylinder and supply to the auxiliary reservoir effects, an accurate adjustment of the brake cylinder pressure corresponding to the rise in train-pipe pressure. When the brake cylinder pressure has reached a low pressure, the auxiliary reservoir pressure is able to raise the diaphragms 5. 27 relatively to the diaphragm 6 so as to connect the passages 30, 31 by the lower cavity 15 to effect the final exhaust of the brake cylinder the passages 34, 35 being also uncovered so that the parts assume the running position. In a modification a pair of superposed slide valves connected respectively to the diaphragms 27, 6.