Actuator having Belleville washer configuration operating in concert with a piston cylinder member

Claim 1

A fluid pressure actuator for a valve having a housing and an actuating stem comprising: an annular housing having one end attachable to the valve housing; a cylindrical piston element concentrically fixedly mounted in the other end of said annular housing and extending into the interior of said annular housing toward said one end; a cupshaped cylinder slidably and sealably mounted on the exterior of said cylindrical piston and defining an annular space between its exterior surface and an interior wall surface of said annular housing; a radially outwardly projecting flange on the open end of said cup-shaped cylinder; conduit means for supplying pressured fluid to the interior of said cylinder to urge same toward the valve housing; resilient means mounted in said annular space and engaging said flange to oppose the fluid pressure produced movement of said cylinder; means for connecting said cylinder to the actuating stem of the valve; said cylindrical piston element having a central bore, an indicating stem slidably and sealingly co-operating with said central bore, and means for connecting the inner end of said indicating stem for co-movement with said cup-shaped cylinder, the length of said indicating stem being only slightly greater than the depth of said piston bore.