Patent GB-914840-A (GB)
Title: Self-lapping driver's brake valve device
IPC: B60T15/04
Filed: 1961-07-03
Abstract: 914,840. Fluid-pressure brakes. WESTING- HOUSE BREMSEN - GESELLSCHAFT. July 3, 1961 [July 8, 1960], No. 23879/61. Class 103 (1). A driver's brake valve device for a fluid pressure-operated braking system comprise a pilot-control valve 1 and a relay valve 2 in which brake pipe pressure is used to lap off the pilot valve and having a charging valve 10 and a compensating valve 11 associated with the pilot valve 1 and that during a fluid pressure-charging operation, the charging valve 10 vents a chamber 27 of the pilot valve and a chamber 29 of the relay valve and an inlet valve 36, 39 of the relay valve is held open during the charging operation to affect connection from a main reservoir pipe to the brake pipe 48. The pilot valve contains a control valve stem 16 coupled to a spring-loaded diaphragm 15 subject on one side 27 to fluid pressure from the charging valve 10 and carrying at one end a piston 18 subject to fluid pressure on one side 19 from the compensating valve 11, the loading of the spring 20 being adjustable such that the pressure at which the pilot valve operates may be regulated. The pilot control valve 1 has a hollow stem 3 rotatable by means of a handle 9, the interior of the stem communicating through radial bores 5 with a chamber 6 surrounding the stem 3. The stem 3 carries cams 7, 8 adapted to actuate, on rotation of the handle 9, the valves 11, 10. Alternatively, the valve 11 may be operated independently of the handle 9. A chamber 13 enclosing the valve 11 is connected by a pipe 23 and choke 24 with the cylinder 19 and a timing reservoir 25 and a chamber 12 enclosing the valve 10 is connected by a pipe 26 with the chamber 27 below a partition 17 and then through pipe 28 with the chamber 29 below a diaphragm 30 in the relay valve and also via a pipe 31 with a chamber 32. A port 34 in the cylinder chamber 21 serves to vent the cylinder 19 and the reservoir 25 with a certain time delay and thereby enable an overcharged main brake pipe 48 to be adjusted to the regulation pressure after such a time interval. The valve stem 3 carries a cam 56 which opens a two-way valve 54, 55 for venting the main brake pipe 48 during an emergency brake application. The relay valve 2 contains two spring- loaded valve tubes 35, 36 coupled to the central diaphragm 30 and engaging valve seats 40, 39. An upper chamber 41 is constantly subjected to the full pressure from a main reservoir pipe 42 and is connected through pipe 43 with the chamber 6 of the contral valve 1. A chamber 47 formed by the valve tubes 35, 36 comprises a part of the main brake pipe 48 and communicates via port 49, chamber 29, and pipe 28 with the chamber 27 above the diaphragm 15 in the control valve 1. A lower chamber 50, open to atmosphere, serves to vent the pipe 48 which is separated from the chamber 47 by a valve 53 having a choke 51. The pipe 48 is supplied with compressed air via the valve 53 which opens or closes in dependence upon the pressure in chamber 32 being lesser or greater than the force of spring 52. Assuming the device is being supplied with compressed air, the handle 9 is moved to " charging " position so that cam 7 opens valve 10 and the compressed air in chambers 27, 29 and 32 is vented to atmosphere through pipe 26 and open valve 10. Simultaneously, cam 8 actuates valve 11 and the main reservoir air fed through pipe 43 and chamber 6, flows through pipe 23 and choke 24 into cylinder 19 and timing reservoir 25. The valve stem 16 rises, lifting a pilot valve member 4 from its seat and allowing chambers 46 and 44 to be filled with main reservoir air. The pressure in chamber 44 causes the diaphragm 30 to descend and lift valve tube 36 from its seat 39 for the whole charging operation, so that the main reservoir air then flows freely into the chamber 47. Because the chamber 32 is vented, the valve 53 lifts so that the main reservoir pressure in chamber 47 flows freely into the brake pipe. When moving back the handle 9 from " charging " position to the " proceed " posision, the valves 10, 11 close and stop the supply of compressed air to the reservoir 25 and close the chambers 27, 29 and 32 to atmosphere, these chambers then being in communication with the main pipe pressure through port 49 and the diaphragm 30 forces the valve tube 36 back on its seat and interrupts the supply of main reservoir air to pipe 48. The valve 53 closes so that the relay valve 2 remains in communication with the main pipe 48 only through the choke 51. The pressure in the timing reservoir still prevails in the cylinder 19 and acts upon the piston 18 and together with the spring 20 is opposed by the main pipe pressure in chamber 27 which forces the valve stem 16 into the cut-off position. As a result of the consequent venting of cylinder 19 and reservoir 25 through choke 34 to atmosphere, the pressure in the main pipe is caused to drop to the level of the regulating pressure preset by the spring 20, the choke 34 being so chosen that during venting the train brake-control valves do not operate. During a normal service brake application compressed air from the main pipe flows through valve 53 acting as a non-return valve and then through open valve stem 35 into chamber 50 which is vented to atmosphere.