| 摘要 |
PROBLEM TO BE SOLVED: To simplify the structure of an impact buffer part, and stabilize the operation of a cylinder by partitioning a cylinder with a piston, and providing an orifice for communicating a first and a second rod side chambers divided by a spring into each other, and making the long size inner peripheral surface slide with a piston rod, and a back-up ring of a short size outer peripheral surface slide with the cylinder. SOLUTION: At the time of raising a platform, a piston discharges the oil of a second rod side chamber 26B between a control member 51 and the piston form a cylinder 20 through an orifice 54 while compressing a spring 52 at the end of an extending stroke of the cylinder 20. Outflow quantity of the oil is restricted by the orifice 54 so as to decelerate the extending speed of the cylinder 20 and so as to buffer the impact between a platform arriving at the raising end and a deck. The control member 51 is formed with a long size inner peripheral surface, which contacts with a piston rod 22, and provided with a back-up ring 53 in the outer peripheral surface thereof, which contacts with the cylinder 20, so as to improve the sealing ability and prevent the oil leakage, and the cylinder 20 decelerating effect in the orifice 54 is improved. With this structure, structural parts for buffering impact is simplified, and the operation of the cylinder 20 can be stabilized.
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