Patent ID: 7267044

Claim:
A double-acting fluid-powered linear actuator comprising: a. a pneumatic or hydraulic rotary actuator coupled with a power screw, b. said rotary actuator comprised of a housing in the form of a cylinder closed at one end with a cylindrical reaction member affixed coaxially inside one end, a piston in the form of a cylinder closed at one end and which fits within said housing such that it divides the interior of said housing into two volumes and such that said piston may rotate and move axially in said housing and partially covers said reaction member, a means producing rotation of said piston with respect to said reaction member when said piston moves axially with respect to said reaction member, a rotor in the form of a cylinder closed at one end and which fits within said housing such that it may rotate but not move axially and partially covers said piston, a means producing rotation of said rotor with respect to said piston when said piston moves axially into said rotor, a pair of ports through which fluid may be delivered alternately to the volume within said housing between said reaction member and said piston and to the volume within said housing remote from said reaction member, such that fluid pressure applied to one port results in said piston both moving axially in one direction and rotating in one direction with respect to said reaction member and said rotor turning in one direction, and fluid pressure applied to the other port results in said piston moving axially in the other direction and turning in the other direction with respect to said reaction member and said rotor turning in the other direction with respect to said piston, c. said power screw comprised of a plunger with screw threads at one end which engage screw threads in the closed face of said rotor, a means guiding said plunger in axial motion, a means restraining said plunger from rotating.