GB1120698A - Valve - Google Patents

Abstract

1,120,698. Valves. NEW YORK AIR BRAKE CO. 29 Nov., 1966 [23 Feb., 1966], No. 53395/66. Heading F2V. [Also in Division F1] A valve plunger 11 which selectively connects the working chambers of a double-acting motor 22 with a supply pump 57 and a reservoir 21 is movable from the " neutral " position shown, in which motor chambers 14, 18 are isolated, to " raise " and " lower " positions, and is provided with a load drop check valve 48 and a coaxial valve 49 which serves to control the bias on valve 48. The plunger is also provided with a check valve 35 and a by-pass valve 38 which, when opened, directs return fluid from the exhausting lower chamber of the motor directly back into the working upper chamber to increase the rate of flow of fluid in the event of the load moving the piston 22a faster than the pump 57 can make up. With the plunger in the " raise " position (Fig. 2, not shown) the pump supplies fluid to the lower end of the cylinder via chamber 15, radial passages 45, valve 48, radial passages 46 and motor chamber 14 whilst the top of the cylinder is opened to exhaust via chamber 18, radial passages 33, bore portion 29, check valve 35, radial passages 34 and chamber 19. Movement of plunger 11 into the " lower " position (Fig. 3, not shown) delivers fluid to the top of the cylinder via chamber 17, radial passages 33, bore portion 29, check valve 35, radial passages 34 and chamber 18, whilst the lower end exhausts into axial bore 43 and bore portion 31 through chamber 14 and radial passages 45, 36, respectively. The pressure on nose 53 of valve 48 tends to unseat it but it remains closed until the pressure on nose 55 of valve 49 is sufficient to overcome spring 54. When valve 49 opens it allows valve 48 also to open whereby fluid entering bore 43 through passages 45 flows to reservoir 21 via check valve 48, valve 49, radial passage 47 and chamber 13, with by-pass valve 38 remaining closed under normal conditions. If, however, piston 22a is moved under load at too great a speed, the back pressure developed by valve 48 will cause valve 38 to open to increase the rate of flow of fluid to the top of the cylinder.