GB1286209A - Fluid control valves - Google Patents

Abstract

1286209 Valves INTERNATIONAL HARVESTER CO 29 May 1970 [10 July 1969] 25924/70 Heading F2V A directional control valve for controlling the supply and exhaust of pressure fluid to and from a motor, comprises a housing with inlet 3 and a motor port 15, 16 or 17, 18. A valve spool 60 is movable from the neutral position shown in which the motor port is isolated, to operated positions wherein it communicates with the inlet or with an exhaust port 20 or 21. Positioned in the inlet is a flow-responsive device which engages the spool in an operated position to hold it there until flow has ceased. As shown, this device comprises a cup-shaped member 90 apertured at 94 and engaging a stem 81 in its lifted position through spring 91 and washer 93. The stem is cammed selectively into detent grooves 67, 68 and in these positions lifts a pilot valve (45), Fig. 2 (not shown), to release pressure from behind a valve piston (41) which then opens to establish the flow into the spool bore. Similar pilot-operated valves 31, 33 are incorporated in the motor ports, actuated by camming surfaces 63, 65 and 72, 73 to allow return flow to the exhaust ports. These valves open automatically when the motor ports are being supplied through the spool bore. The spool is spring centred by means 100. In a float position of the spool to the far right, designated by lettered line F, the stem 81 drops down a cam surface 74 to allow the inlet valve (41) to close, whilst the valves 31, 33 in the motor ports are actuated to open position by cam surfaces 62, 64 and 73, the motor ports being then in direct communication with each other and with the exhaust ports, through chambers A to E. In this position, the spool is held by a garter spring 106 engaging a shouldered surface 75 of the spool.