Patent ID: 7603943

Claim:
A linear actuator for a rotating shaft assembly, comprising: a cylinder member; a primary piston arranged within a cavity defined by said cylinder member, wherein a first face of said primary piston delimits a first chamber within the cavity and a second face of said primary piston delimits a second chamber within the cavity; a rotatable shaft fixed to said primary piston, said rotatable shaft defining a first main passage in fluid communication with the first chamber and defining a second main passage in fluid communication with the second chamber; a pressure delivery body fixed to said rotatable shaft, said pressure delivery body defining a first delivery passage in fluid communication with the first main passage and defining a second delivery passage in fluid communication with the second main passage, wherein said pressure delivery body comprises a passage isolation system for selectively isolating fluid communication between the first delivery passage and the first main passage and fluid communication between the second delivery passage and the second main passage; and a pressure limiting system for selectively blocking fluid communication through the first main passage and the second main passage, wherein said primary piston, said rotatable shaft and said pressure delivery body are axially movable with respect to said cylinder member, and said cylinder member, said primary piston and said rotatable shaft are rotationally movable with respect to said pressure delivery body, wherein fluid pressurization of the first chamber actuates said rotatable shaft in a first axial direction, and blocking fluid communication through the first main passage after fluid pressurization substantially maintains the actuation of said rotatable shaft in the first axial direction, and wherein fluid pressurization of the second chamber actuates said rotatable shaft in a second axial direction, and blocking fluid communication through the second main passage after fluid pressurization substantially maintains the actuation of said rotatable shaft in the second axial direction.