Patent GB-348695-A (GB)
Title: Improvements in and relating to fluid pressure braking apparatus
IPC: B60T15/18
Filed: 1930-02-17
Abstract: 348,695. Fluid-pressure brakes. WESTINGHOUSE BRAKE & SAXBY SIGNAL CO., Ltd., 82, York Road, King's Cross, London.-(Assignees of Farmer, C. C. ; 7008, Thomas Boulevard, Pittsburg, U.S.A.) Feb. 17, 1930, No. 5231. Convention date, March 9, 1929. [Class 103 (i).] The control reservoir of a distributing valve for an automatic compressed air brake system is adapted to be temporarily overcharged to permit charging of the auxiliary reservoirs without completely releasing the brakes. The valve described is of the kind in which brake cylinder and auxiliary reservoir pressures act against the normally constant pressure in a control reservoir to effect graduated release of the brakes and it may also act to restrict the supply to the auxiliary reservoir in charging if the pressure therein rises too rapidly. The equipment shown comprises a triple valve 1 ; a piston valve 64 which restricts the supply to an " empty " brake cylinder 7 when the pressure therein reaches a predetermined value and then connects a second or " load " cylinder 8; a graduated release valve 2; and a valve 3 for charging the control reservoir 10 of the valve 2 and for discharging it into the brake cylinders in emergency applications. In initially charging the system air flows from the train-pipe 11 to the triple valve chamber 12 and by passage 84 through groove 42 in the stem 39 of the release valve 2, chamber 35 and passage 19 to the auxiliary reservoir 9 and the triple valve chamber 18. Train-pipe air also flows by passage 13 to chamber 59 of the valve 3 and moves the diaphragm 55 and valve 57 to open the supply to the control reservoir 10 from passage 19. The valve 2 comprises diaphragms 23, 24 the space between which is open to atmosphere by port 29 ; a chamber 30 above the diaphragm 23 is connected to the control reservoir 10 by passage 63 ; a chamber 20 connected to the brake cylinder in the release position of the triple valve 1 by passage 90, check-valve 4, valve cavity 94 and passage 95. The lower chamber 35 being at auxiliary reservoir pressure this pressure is normally equal to that in chamber 30 so that spring 38 moves the diaphragms and a valve 21 to open a passage 85 leading to a restricted exhaust port 88. The brake cylinder and chamber 20 are thus exhausted. When the train-pipe pressure is reduced to apply the brakes, the auxiliary reservoir 9 supplies the brake cylinder 7 through the valve port 102, passages 93, 103, 92, 90. When the brake cylinder pressure reaches a value sufficient to overcome the spring 69, the valve piston 64 moves down causing the check-valve 4 to seat so that the brake cylinder is supplied only by the restricted passage 103. At the same time the piston 64 closes the exhaust port 100 of the load cylinder 8 and opens the passage 99 so that this cylinder is supplied. This cylinder is provided with a piston-rod 77 which moves freely outwardly within the part 75 when the piston of the cylinder 7 moves out, but is coupled thereto by the latch 78 when the piston 74 commences to move, by the disengagement of the latch from a fixed pin 81. A graduated release of the brakes may be effected by raising the train-pipe pressure a predetermined amount, thus returning the triple valve to the release position and raising also the pressure in the auxiliary reservoir and chamber 35 of the valve 2, thus causing the exhaust of the brake cylinder 8 through the restricted port 88 by the opening of the passage 85. When the brake cylinder pressure in the chamber 20 falls to a value corresponding to the rise of pressure in the chamber 35 the valve 21 is moved downwardly to cut-off the exhaust. If during the release operation the pressure in the auxiliary reservoir and chamber 35 rises more rapidly than corresponds to the exhaust of the chamber 20 through the port 88, the diaphragms 23, 24, 25 are forced upwardly to compress the spring 32, permitting upward movement of the stem 39 so that a circular slot shown at the end of the groove in the stem 39 is restricted by the casing. The supply to the auxiliary reservoirs at the front of a train may thus be restricted to ensure the prompt release of the triple valves at the rear. If it is desired to charge the system without completely releasing the brakes as on a down grade the system including the reservoir 10 and chamber 30 is initially overcharged. If then, after an application of the brakes, the train-pipe pressure is raised only to the normal value, the exhaust valve 21 will close when the brake cylinder pressure has fallen to a value dependent upon the degree of overcharging of the chamber 30. The pressure in this chamber and in the reservoir 10 may be brought to the normal value by first effecting an abnormal or emergency reduction of train-pipe pressure so that the air in the reservoir overcomes the spring stop 60 and escapes through passage 19 to the auxiliary reservoir, and then recharging the system to the normal value. The discharge of air from the reservoir 10 to the auxiliary reservoir increases the brake cylinder pressure in emergency applications. The reservoir 10 may however be arranged to exhaust to atmosphere or to a separate container. A cock 187 may be turned to connect the passage 95 to the exhaust port 88 thus suppressing the graduated release action of the valve 2. Specification 141,785, [Class 103 (i), Brakes &c.], is referred to.