GB688073A - Hydraulic control valve with automatic hold and release - Google Patents

Abstract

688,073. Hydraulic valves. BENDIX AVIATION CORPORATION. Oct. 26, 1950 [Oct. 31, 1949], No. 26156/50. Class 135. A hydraulic control valve comprising a valve member movable in a body member and manually operable against resilient means to actuate a doubleacting jack is held in its operative position by a spring detent carried by one of the members and a pair of relatively movable elements on the other member which are normally separated to provide a gap therebetween engageable by the detent and movable toward each other to close the gap by pressure responsive means on the pressure in the valve inlet exceeding a predetermined value to return the valve member to its neutral position. The control valve 14, Fig. 2, comprises a piston member 24 slidable in a body member 22 and manually movable from its neutral position shown by a lever 15 against a return spring 50 tocontrol supply, exhaust and motor parts 25 ... 28. The piston is formed with transverse bores 33, 31, 65 communicating with an axial bore 32 slidably mounting a spring-loaded piston valve 34 connected by a pin 35 to a sleeve element 36 slidable over an extension 24e of the piston 24. A pin 40 connects the extension 24e to a surrounding sleeve element 41 defining a gap 45 between the sleeve elements which co-operates with spring detents 48, 62 carried in annular grooves 49, 63 in the valve body when the valve is in its neutral position. On anti-clockwise movement of the lever 15, the piston 24 moves to the right to supply the left-hand end of the jack 10 with pressure liquid and connect its other end to exhaust, the sleeves 36, 41 moving with the piston 24 until the gap 45 reaches the detent 48 which engages the gap and holds the valve in its operating position and permits the release of the lever 15 by the operator. On completion of the jack stroke, pressure builds up in the inlet 25 to overcome the spring 39 and move the piston valve 34 to return the liquid to exhaust through passages 32, 65, 66 and move the sleeve 36 to abut the sleeve 41, whence the detent 48 is urged into its groove 49. The piston 24 is then returned to its neutral position by its spring 50. Conversely, on clockwise movement of the lever 15, the detent 62 is forced out of its groove 63 to hold the valve in its operative position and released therefrom on movement of the valve piston 34 on the predetermined pressure again being reached in the inlet 25.