Patent GB-1012515-A (GB)
Title: Improvements relating to graduated release valves
Inventor: SIMMONS ARTHUR WILLIAM
IPC: B60T15/18
Filed: 1962-10-11
Abstract: 1,012,515. Fluid pressure brakes. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. Sept. 18, 1963 [Oct. 11, 1962], No. 38531/62. Heading F2F. A graduated release-valve RV for a direct release triple valve TV comprises a stem 9 which connects two opposing diaphragms, one, 7, being subject to brake exhaust pressure in the chamber 6 from the triple valve at EC and to the atmosphere in the chamber 66, and the other 14 being subject to auxiliary reservoir pressure (AR) in the chamber 11 and to control reservoir pressure in the chamber 17; the arrangement being such that an initial movement of diaphragm 14 relative to the stem 9 closes a charging connection 20 from the auxiliary reservoir AR to the control reservoir in the space 17 at the start of brake application, whilst during brake release movement of the diaphragm 14 and stem 9 together towards a release position obturates at 29 the charging passage 30 between the auxiliary reservoir AR and the auxiliary reservoir chamber of the triple valve TV. The chamber 6 connects to atmosphere at 2 through a valve 3/4 of which the top of the stem 9 forms part but a spring 5 normally urges the diaphragm 7 downwards. The stem 9 passes through a gland 8 into chamber 27 which connects with the auxiliary reservoir chamber (AC) of the triple valve TV and also with the chamber 11 through a check valve 26. The lower end 22 of the stem 9 extends into a diaphragm follower 13, which with a lower follower 16 clamps diaphragm 14 and holds it; urged by a spring 12, against stops 15 The stem end 22 co-operates with a soft seat 19 to form a valve 19/22 which obturates the bore 18 in the follower 13 to prevent passage through the bore 20. The spring 12 also holds a perforated washer 24 up against an opening between the chambers 27 and 12 which can be closed or regulated when a shoulder 29 on the stem moves relative to a shoulder 28. A manually operated release valve MV is connected to the control reservoir 17. During charging up and with the apparatus empty the graduated release valve RV takes up the position shown in the drawing. Upon charging up the brake pipe BP air passes through the triple valve TV; entering the chamber 27 through the connection AC and port 25, and thence between the shoulders 28, 29, through holes 23 into chamber 11 and thence via 10 to the auxiliary reservoir AR. Air can also pass through bore 20 into the control reservoir 17. On applying the brake the brake pipe pressure is dropped and air from the auxiliary reservoir flows through chambers 11 and 27 and out to the triple valve port check valve 26. The drop in the auxiliary reservoir pressure in chamber 11 allows the diaphragm 14 to lift against the spring 12 and close valve 19/22 thereby isolating the fully charged control reservoir 17. At the same time the valve 3/4 closes, but with the triple valve in the brake applying position there is no pressure in the chamber 6. When the brake is released by an increase of pressure in the brake-pipe the triple valve will exhaust the brake cylinder BC through EP into the chamber 6 and brake pipe pressure will flow through the feed-groove of the triple valve into chambers 27 and 11. As the auxiliary reservoir pressure increases on top of diaphragm 14 it will reach near to a balance with the control reservoir pressure beneath it so that the pressure on top of the diaphragm 7 will move down to open the valve 3/4 and exhaust chamber 6. If recharge of the auxiliary reservoir 13 then stopped, the valve 3/4 will close again, and prevent further release of brake cylinder pressure. By subsequent increments of brake pipe pressure, and consequently of the auxiliary reservoir pressure, the brake cylinder pressure can be released in steps. If, however, the brakes are reapplied after partial release, the chamber 6 will be again cut off from pressure. Towards the end of complete release when the auxiliary reservoir pressure has nearly equalled that in the control reservoir the spring 12 can overcome the difference to move diaphragm 14 downwards and open valve 22/19 to reconnect these reservoirs. To further delay the exhaustion of the brake cylinder a small choke (not shown) may be located in the connection 2. If, due to temporary boosting of the brake pipe pressure, during gradual brake release in long trains, the auxiliary reservoir pressure rises more quickly than the brake cylinder pressure falls in chamber 6, the excess downward pressure on diaphragm 7 will exceed the upward pressure on diaphragm 14 and cause stem 9 to move downwards, moving the shoulders 28 and 29 closer together and choking the flow from the auxiliary reservoir chamber of the triple valve to the auxiliary reservoir AR, to prevent overcharge. The invention may be adapted to-vacuum brakes.