GB1237530A - Spool valves - Google Patents

Abstract

1,237,530. Valves. TEMPLE INSTRUMENTS Ltd. 10 Dec., 1969, No. 60204/69. Heading F2V. A valve for controlling a pneumatic system comprises a spool 19 having opposite ends of equal effective area, a first passage 63, 67 extending through the spool between the ends thereof, an inlet 22 for line pressure, a second passage 65 extending between the first passage and the inlet, a spigot 33 received in the first passage with clearance 64 and communicating with a vent 31, the spool having first and second equilibrium positions adjacent the first and second ends of the body and the clearance 64 being so arranged that when the vent is opened the pressure at the lower end 76 of the spool drops more rapidly than the pressure at the upper end of the spool and the spool moves downwardly to its second equilibrium position, and means 49 to restore the spool to its first position. The movement of the spool connects a service port 45 carried by a rotatable ring 38 with the inlet port 22 or with an exhaust port 46. The valve may form part of a manifold block 10 and be connected to a manifold supply line through a port 14. Connection of the passage 63 to the vent 31 is controlled by a spring-loaded, solenoid-operated plunger 29 and the means to restore the spool to its first position consists of a piston 49 lifted by applying pilot pressure to a port 55.