| 摘要 |
An improved hydraulic work support (10) having a plunger (18) that is shifted between retracted and extended positions by hydraulic fluid is disclosed. The work support includes a base (12); a tubular housing (14) partially received in the base and having a central bore (40); a tubular sleeve (16) received within the central bore; a general cylindrical plunger (18) positioned at least partially within the sleeve, the plunger being movable within the bore along the longitudinal axis; and a piston cylinder assembly (20) positioned within the central bore for selectively shifting the plunger along the longitudinal axis of the bore between a lowered, retracted position and a raised, extended position under the influence of hydraulic fluid. The piston cylinder assembly includes a cylinder (94) positioned within the sleeve and having a piston chamber (96) formed therein; a piston (98) movably received within the piston chamber; and an elongated piston rod (100) having a lower end coupled with the piston and an opposite upper end extending from the cylinder and coupled with the plunger. The piston and piston rod are shifted upward in the piston chamber when fluid is delivered to a first fluid passageway (34) formed in the base to shift the plunger to its raised, extended position. The piston and piston rod are shifted downward in the piston chamber when fluid is delivered to a second fluid passageway (36) formed in the base to return the plunger to its lower, retracted position. |
