GB636089A - Improvements relating to triple valves for compressed air braking systems - Google Patents

Abstract

636,089. Fluid-pressure brakes. WESTING- HOUSE BRAKE & SIGNAL CO., Ltd. Dec. 31, 1947, No. 34994. Convention date, July 12, 1946. [Class 103 (i)] A triple valve of the kind which operates to limit the rate of recharging of its associated auxiliary reservoir 95 in accordance with the rate of exhaust of the brake cylinder 96, is characterized in that there is provided a supply valve 17 for the control of fluid under pressure from a brake pipe 18 through an intermediate chamber 10 to the auxiliary reservoir 95, and an exhaust valve 97 which is opened when the pressure in the intermediate chamber 10 exceeds a pre-determined value dependent upon that in the brake cylinder 96 acting in chamber 9, the triple valve being controlled by the combined actions of the pressure in. a control chamber 6, connected to a control reservoir 94, the brake cylinder pressure in chamber 9 and the pressure in the intermediate chamber 10 in such a way that upward deflection of the diaphragm pile 3, 4, 5 first closes the supply valve 17 and then opens the exhaust valve 97 to atmosphere by way of the chamber 8. The triple valve is shown in the release position in which the brake cylinder and thus chamber 9 are at atmospheric pressure and therefore do not influence the movement of the main valve stem. Charging of the auxiliary reservoir from the brake pipe 18 is carried out by way of chamber 10, passage 50, check-valves 48, 62 and pipe 12, the lower diaphragm pile being moved upwards to close the valve 17 whenever the pressure in chamber 10 exceeds that in chamber 6 by from 2 to 3 lbs. per square inch, as determined by the regulating spring 28. When the driver, to apply the brakes, causes a drop in pressure in the brake pipe 18, return flow of air from the auxiliary reservoir 95 to chamber 10 is prevented by the check valves 48 and 62. The drop in pressure in chamber 10 causes the diaphragm pile to move downwards so that the stem 21 together with the graduating slide-valve 32 drop until the lost motion between the collar 35 and the upper end of the main slide valve 30 is taken up. This movement of the graduating slide valve 32 covers the port 90, thus cutting off also communication between the reservoir 95 and brake pipe 18 by way of restricted passage 49, blocks ports 80 and 82 by which the brake cylinder 96 is connected to exhaust outlet 56, and uncovers the port 89 in the main slide valve. Continued downward movement of stem 21 compresses spring 36 between collar 35 and projection 34 until the graduating slidevalve 32 is lowered sufficiently to put the brake pipe 18 into communication with the accelerating bulb 52 by way of channel 50, check-valve 48, ports 93 and 88 and port 86. Further downward movement of stem 21, carries down the main slide-valve 30, putting the port 89 into communication with the channel 59 so that compressed air can then flow from the auxiliary reservoir 95 past the opening in shot-valve 67 to the brake cylinder 96 to apply the brakes. Consequent reduction in pressure in the auxiliary reservoir 95 causes downward movement of the upper diaphragm plate 25 under the action of the control reservoir pressure in chamber 6 so as to close valve 41. Thereafter the diaphragm 2 acts solidly with the lower diaphragms and braking is controlled only by the difference in pressure between the control reservoir 94 and brake-pipe 18.