Patent GB-266725-A (GB)
Title: Improvements in distributors for fluid pressure brakes
IPC: B60T15/30
Filed: 1927-02-23
Abstract: 266,725. Bozic, D. Feb. 23, 1926, [Convention date]. Fluid-pressure.-A distributor valve for automatic compressed-air brake systems is adapted to vent the train-pipe to the brake cylinder at the commencement of a braking operation so as rapidly to develop the pressure in the cylinder and to propagate the wave of depression in the train-pipe throughout the length of the train. A diaphragm 8 separates a chamber 9 maintained constantly at the initial train-pipe pressure from a chamber 6 connected to the train pipe by the passage 7. A piston 2 resting on the diaphragm 8 encloses pistons 12, 13. The rod 14 of the piston 13 is slidably disposed in the rod 11 of the piston 2 and engages a lever 4 pivoted at 5 and having its other arm connected to a piston 3 subject to the opposing pressures in the brake cylinder connected at 18 and in a chamber 15 open to atmosphere by a port 16. The upper faces of the pistons 12, 13 are open to the chamber 15 by the passage shown. The lever 4 controls a hollow rod 20 provided with a port 22 adapted in the position shown to connect the chamber 15 to a passage 19 connected to the brake cylinder. The rod 20 controls an inlet valve 24 for the brake cylinder. The train-pipe is also connected bv passage 50 to the chamber 35 of a piston 32 subject also to the pressure of a spring 33 and the pressure in the chamber 9 and actuat. ing a shoulder 29 which controls a passage 31 leading from the auxiliary reservoir. Bv turning a cock 49, the chamber of the piston 32 may be connected to the chamber 25. A piston 38 normally seats on a valve 40. the stem 41 of which is held against the casing by a spring 42 abutting also on a part 44 which mav be lifted by a projection 43. In running conditions, the parts are in the position shown and air from the trainpipe is supplied to the auxiliary reservoir by way of the valve 27 the shoulder 29 and passage 31. and to the chamber 9 by way of the valve 40 and passages 36. 37. If the train-pipe is reduced the pistons 2, 12, 13 are raised by the superior pressure in the chamber 9 and the rod 20 and valve 24 thereby raised to cut off the brake cylinder from the atmospheric chamber 15 and permit air from the train-pipe to flow to the brake cylinder past the valve 27. When the depression in the train-pipe pressure is sufficient the pressure in the chamber 9 acting on the upper face of the piston 32 overcomes the spring 33 and the shoulder 29 is moved into the chamber 25, to allow air from the auxiliary reservoir to flow into the brake cylinder, and to engage the valve 27 so as to cause a throttling shoulder 28 on this valve to enter the passage 7. As soon as the brake cylinder pressure acting on the piston 3 reaches a certain value the piston 13 is moved back until it engages the piston 12 and such movement may be sufficient to cause the throttling shoulder 16 on the valve 24 to enter the valve passage depending on the thickness of the right-hand arm of the lever 4. Finally, if the venting of the train-pipe is stopped by the driver, the pistons 2, 12, 13 move back together, and the valve 24 closes. The brakes may be released in the usual way by raising the train-pipe pressure or by press. ing the projection 41 by hand so as to lift the piston 28, thereby exhausting the chamber 9 through the chamber 19 and with cock 46 in the position shown the auxiliary reservoir also. The cock 46 mav be turned to connect the chamber 39 to the train-pipe passage 7.