Patent GB-616951-A (GB)
Title: Improvements relating to fluid pressure braking apparatus for railway and other vehicles
IPC: B60T8/32
Filed: 1946-09-25
Abstract: 616,951. Fluid-pressure brakes. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. Sept. 25, 1946, No. 28617. Convention date, Sept. 26, 1945. [Class 103 (i)] A centrifugal regulator acts to reduce the brake cylinder pressure, if a vehicle wheel locks or if locking is imminent, through a relay valve which is such that it is unaffected by the gradual reduction of pressure effected by the regulator due to fall of speed at normal rate. The regulator may be that which also acts to vary the pressure in the same or another brake cylinder in accordance with the speed as distinguished from the temporary reduction effected through the relay valve. According to Fig. 1, upon operation of a control valve 2 by the driver, compressed air is supplied past the valve 22 of a centrifugal regulator 4, to the chamber 14 of a relay valve and equalizes through a groove 16 to the chamber 15 so that the slide valve 20 assumes the position shown, by the pressure of a spring 13. Compressed air is thus supplied to the brake cylinder 3 through the valve passage 19. As the speed falls, the chamber 14 is opened to atmosphere by the regulator 4 through the valve 23 and if the fall is at the normal rate the equalization of the pressure in chamber 15 is substantially maintained by leakage through the groove 16. But if due to locking of the wheels or the imminence of locking, the fall of speed is sudden, the valve 20 is moved by the piston 12 to connect the cylinder 3 to atmosphere by the port 24. When the locking ceases, the brake cylinder pressure is restored to its original value. According to Fig. 2 without the valves 26, 27, 28 shown in broken lines, when the control valve 2 is operated, compressed air is supplied from reservoir 1 not only to brake cylinder 3 but also to an auxiliary cylinder 31 through the slide valve 20. The supply to the cylinder 3<SP>1</SP> is determined, however, in' accordance with the speed by a relay valve 25 under the control of the regulator 4. Air supplied to the chamber 32 by the regulator 4 acts on a diaphragm 33 to open a supply valve 36 for the cylinder 3<SP>1</SP>, this valve being closed by the . cylinder pressure acting on a second diaphragm 38. As the speed falls, due to normal retardation, the pressure in cylinder 3<SP>1</SP> is correspondingly reduced through port 30 by the cylinder pressure acting on the diaphragm 38 against the falling pressure in chamber 32 to unseat the exhaust valve 35. If due to locking or the imminence of locking of a wheel, the pressure in chamber 14 is suddenly reduced, the slide valve 20 is operated to connect the cylinder 3 and pipe 29 to exhaust port 17 and the relay valve 25 is operated to connect the cylinder 3<SP>1</SP> to exhaust port 30. As soon as the wheel locking ceases, the valve 20 returns to the position shown so that the pressure in the cylinders is restored, that in the cylinder 3<SP>1</SP> being in accordance with the vehicle speed at the moment. If the discharge valve 28 and non-return valves 26, 27 are included, the relay valve 25 is operated in an application, to set up a pressure in cylinder 3<SP>1</SP> in accordance with the speed. Pressure air is also supplied by the regulator 4 to chamber 44 of the valve 28 and acts against the spring 42 to seat the valve 41. If the speed falls at the normal rate, the pressure in both the cylinders 3, 3<SP>1</SP> remains unaffected until the speed has fallen to about 30 miles per hour. The pressure in chamber 44 reduced by the regulator 4 is then insufficient to hold the valve 41 in the seated position so that the chamber 32 of valve 25 is exhausted through port 31, causing complete release of the pressure in cylinder 3<SP>1</SP>. If, however, wheel-lock occurs, the valve 20 is operated to connect both cylinders to the exhaust port 24 as above described. An antilocking device arranged to control all the brake cylinders of a vehicle may be mounted on an axle which is more strongly braked than the others or centrifugal regulators controlling a single anti-locking valve may be mounted on each axle so that the locking of one axle effects the exhaust of all the brake cylinders. The relay valve 25, Fig. 2, may be omitted or a similar valve may be provided also for the cylinder 3. According to the Specification as open to inspection under Sect. 91, the pressure in a single brake cylinder may be established by a relay valve having two control chambers, both supplied with compressed air by a control valve 2, but the pressure in one chamber being determined in accordance with the speed by a centrifugal regulator. Pressures corresponding to those set up in the cylinders 3, 3<SP>1</SP> of the system shown in Fig. 2 are in this case set up in the two cylinders of the relay valve to determine the pressure in a single cylinder. This subject-matter does not appear in the Specification as accepted.