| 摘要 |
A device comprising a cylinder, a piston in the cylinder, a rod extending through the piston, the rod being fast to one end of the cylinder and projecting through the other end of the cylinder, the piston being slidable on the rod, a head on the outer end of the rod, the cylinder having a fluid inlet in said first end to force the piston toward said head so as to clamp an article between the piston and head, and a spring for retracting the piston when fluid pressure is stopped, the spring surrounding said rod between the piston and head and said inlet extending through the rod.
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