Patent GB-353024-A (GB)
Title: Improvements in triple valves for compressed air brakes
IPC: B60T15/30
Filed: 1930-04-17
Abstract: 353,024. Fluid-pressure brakes. KASANTZEFF, F., 11, Lietzenburgeratrasse, Berlin. April 17, 1930, No. 12235. [Class 103 (i).] A triple valve for automatic compressed air brakes, comprises a diaphragm subject on its sides respectively to a constant fluid pressure and to the train pipe pressure and a second diaphragm subject to the brake-cylinder pressure, the diaphragms operating braking-cylinder supply and exhaust valves, and the first diaphragm carrying a spring whereby the brake-cylinder pressure is limited to a maximum. There may be two diaphragms which may be rendered selectively subject to brakecylinder pressure to obtain different pressures according to the vehicle load. The valve mechanism comprises a diaphragm L carrying a casing 23 for a spring 22 adapted to abut on a rod 21 secured to a pair of diaphragms M, N. The rod 21 slides in a fixed partition O and is adapted to engage the stem of a pair of valves 181, 18<11> which control communication of the chamber I with the auxiliary reservoir B and through the passage 19 with the chamber G which is constantly connected to atmosphere by the port 26. The chamber I is connected to the brake cylinder A with the cock 16 in the position shown, the chamber H between the diaphragms M, N is connected to atmosphere by the passage 15 and the smaller diaphragm N is thus effective but the cock may be turned to connect the chamber H to the chamber I by the passage 17 and thus to the brake cylinder, the diaphragm M being then effective. A piston 20 open at its upper face to the chamber I and controlling passages 5, 7, 9 is normally held in the raised position shown by the pressure in the train-pipe connected to the passage 3. The underface of the upper part of the piston is connected to the atmosphere port 26 and in the normal position shown, the groove 11 connects the chamber I also with the port 26. The train pipe D is constantly connected to the chamber F through the throttled passage 2 and normally also through the passages 3, 5, 6. The auxiliary reservoir B is charged through the passage 3 past the non-return valve 12 and also through the passages 9, 10. The chamber E with the reservoir C is charged through the passages 7, 8. When the train-pipe pressure is reduced, the pressure falls more rapidly in the chamber F than in the chamber E so that the diaphragms move to the right and at the same time the piston 20 falls cutting off the passage 5, 7, 9 so as to isolate the chambers E, C and leaving open only the throttled connection 2 between the train-pipe and the chamber F, whereby the fall of pressure in the chamber F and the corresponding rise of braking pressure is rendered substantially constant throughout the train. The movement to the right of the diaphragms causes the rod 21 to open the valve 181 so that air is applied from the reservoir B and also from the train-pipe past the valve 12 to the chamber I and the brake cylinder A until the diaphragms L, M, N are returned to the position shown to close the valve 18<1>, by the brake-cylinder pressure acting either upon the diaphragm M or the diaphragm N. When however the brake-cylinder pressure reaches a maximum value sufficient to compress the spring 22, the diaphragms M, N return to close the valve 181 irrespective of the fall of pressure in the chamber F. The value of the maximum pressure will depend on whether the diaphragm M or N is effective. The release of the brakes may be graduated by raising the train-pipe pressure step by step the diaphragms moving to the left by the increase of pressure in the chamber F, so as to open the valve 18<11> and permit the escape of air from the brake cylinders through the passage 19 and port 26 until equilibrium is again established.