GB1520741A - Actuators - Google Patents

Abstract

1520741 Stroke speed varying DOBSON PARK INDUSTRIES Ltd 1 July 1975 [29 June 1974] 28964/74 Heading F1D [Also in Division F2] An actuator, for example for a valve 15, comprises a piston 2 moving in a bore 3 under the influences of fluid-pressure admitted to a chamber 5 via passageways 10, 9 and a groove 4a in a spring- loaded plate 4. When the piston has moved sufficiently to open an annular port 11 the con- trolling fluid is substantially unrestricted and the piston is accelerated. On the reverse movement of the piston the plate 4 lifts against the spring 6 to allow rapid exhausting of the chamber 5. In an alternative embodiment, Fig. 3 (not shown) a needle valve (12) adjusts the flow through a bore (13) leading into the chamber 5 in place of the groove 4a. The degree of opening of the needle valve may be remotely controlled. In a further alternative, Fig. 5 (not shown) control fluid flows into the chamber 5 via spring- loaded ball-chuck valves which restrict the flow through the passages 9 into the chamber 5. Bleed channels (18) in the end of the piston 2 communicate with the annular port 11 at the end of the return stroke of the piston.