Three Position Power Cylinder.

An assembly for moving objects by mechanical linkages has a power cylinder with a shoulder at the juncture of a small bore and a large bore and with ports adjacent each end and one adjacent the shoulder. A shaft extends through the cylinder with a larger diameter portion in the smaller bore with a piston thereon sealing against the surface of the smaller bore. A second piston slidably seals on the small diameter of the shaft and against the larger bore, being biased towards the shoulder by a spring. A lost motion device on the end of the shaft projects outwardly of the smaller bore end of the power cylinder and has a housing with a chamber in which the end of the shaft is slidable against a spring which biases it outwardly of the housing. Pressurized fluid when supplied to the ports in the large portion of the power cylinder moves the shaft within the lost motion device against the spring to move the lost motion device, and when supplied to the ports at the ends of the power cylinder, permits the spring of the lost motion device to bias the piston shaft in the direction of the large bore. When supplied only to the port in the smaller diameter bore, the shoulder on the piston shaft will move the slidable piston against its spring and the piston shaft is moved still further in the direction of the large bore. When a pair of positioning members is attached to opposite