| 摘要 |
A power cylinder of the type in which the piston may be locked to maintain am associated tool or clamp in a fixed position. A nut is provided in an end wall of the cylinder and the piston rod of the piston passes through the nut. The initial portion of the forward stroke of the piston is accomplished by the introduction of fluid pressure into the cylinder and, as the piston approaches the final portion of its stroke, the threaded portion of the piston rod engages the nut whereupon the nut is rotated to threadably advance the piston through the final portion of its stroke. The rotation of the nut is accomplished by pressurized fluid acting against a piston rack which rotates a gear which in turn rotates the nut. The center line of the piston rod is offset from the center line of the piston to preclude rotation of the piston and of the piston rod.
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