Power cylinder and control unit

Claim 1

A SELF-CONTAINED POWER CYLINDER AND CONTROL WHICH COMPRISES A CYLINDER HAVING A HEAD END AND ROD END, A PISTON IN SAID CYLINDER, SAID HEAD END HAVING A RESTRICTED UNIDIRECTIONAL OUTLET VALUE FOR RESTRICTING THE FLOW OF AIR, A BY-PASS MEANS CLOSABLE BY SAID PISTON TO DIRECT OUTPUT AIR TO SAID UNIDIRECTIONAL VALVE AS THE PISTON APPROACHES THE HEAD END, AND AN INLET PORT ON SAID HEAD END FOR DIRECTING AIR TO SAID PISTON, SAID ROD END OF SAID CYLINDER CONTAINIG PILOT-OPERATED CONTROL VALVES, ONE OF SAID VALVES BEING NORMALLY OPEN TO DIRECT PRESSURE FLUID FROM A SOURCE TO THE PISTON AT THE ROD END AND THE OTHER BEING NORMALLY CLOSED TO DIRECT EXHAUST FLUID FROM THE HEAD END OF SAID CYLINDER TO AN EXHAUST OPENING, EACH OF SAID VALVES BEING SHIFTABLE BY PILOT PRESSURE TO POSITIONS WHERE THEY CHANGE THEIR RESPECTIVE FUNCTIONS TO DIRECT PRESSURE TO THE INLET PORT AT THE HEAD END OF THE CYLINDER AND TO CONNECT THE ROD END OF THE CYLINDER TO EXHAUST.