GB750582A - A triple valve for air brakes, more particularly for railway vehicles - Google Patents

Abstract

750,582. Fluid-pressure brakes. KNORRBREMSE GES. July 23, 1954 [July 24, 1953], No. 21612/54. Class 103 (1). In a triple valve for air brakes, more particularly for railway vehicles, the constant pressure chamber of the triple valve and the main air supply line are interconnected through a pipe provided with a control device having a sensitivity aperture which is adapted to reduce the flow of air when there is still some residual pressure in a brake cylinder and which only fully releases the residual pressure when the brake cylinder is substantially devoid of pressure and wherein an accelerator is adapted to bleed the main air supply line and is arranged to have reached an operative position when the line between the constant pressure chamber and the main air supply line is open, but having the sensitivity aperture throttled by the control device. In the arrangement shown applied to a railway vehicle in which the brake is shown in its fully released position, air is supplied from the main air line 1 to charge the auxiliary reservoir 79 through a non-return valve 83. Flow from the auxiliary reservoir 79 to the brake cylinder 75 is controlled by the triple valve 5 which, in the position shown, is inoperative, the pressure in the control chamber 13 and the chamber 9 on each side of the control piston 11 being equal. When a brake application is made the pressure in the main air line 1 is reduced to reduce the pressure in chamber 87 of the accelerator 3 so that the increased pressure in the chamber 89 forces the actuating piston upwardly to open the two-way valve 113, 111, the main air line pressure being further reduced by bleeding air into the transfer chamber 115 via pipe 119 and open valve 113. The valve 101, being open during this operation, allows air to escape to atmosphere via port 97 from chamber 89 permitting the piston 85 and valve 101 to close and exhaust the chamber 115 to atmosphere via port 107. This local bleeding of the main air line 1 and hence in chamber 87 of the accelerator and chamber 9 of the triple valve allows the triple valve control piston 11 to be forced upwardly by the constant pressure in the control chamber 13 to open valve 27 and permit air to flow from the auxiliary reservoir 79 via pipe 77 to the brake cylinder 75 to apply the brakes. This pressure actuates piston 73 of a device 69 to close connection between the main air line 1 and the control chamber 13 via control device 53. Further bleeding of the main air line by the accelerator 3 is prevented by the auxiliary reservoir pressure acting on piston 125 to close valve 123. During the final stages of release, the control chamber 13 can be prematurely placed in communication with the main air line by the opening of the control valve 71 when there is only residual pressure in the brake cylinder 75; the accelerator valve 3 being also placed in its operative position ready for re-application of the brakes; risk of " static exhaustion " being prevented by the throttling effect of the needle 63 in the sensitivity bore of the control device 53; the needle 63 being allowed to return to the position illustrated only when the brake cylinder 75 has been completely evacuated.