| 摘要 |
A piston (19) inserted in a tubular housing (2) is connected to a clamp rod (5). A lock chamber (20) is provided on the upper side of the piston (19), and an annular valve chamber (41) is formed in the peripheral wall of a rod hole (18) in which the clamp rod (5) is inserted. In the last stage of swing and ascent of the clamp rod (5), a shuttle member (42) fitted over the lower part of the clamp rod (5) rises and fits into the valve chamber (41) by an effect of differential pressure of pressure oil acting when the shuttle member (42) starts to fit into the valve chamber (41). Then, the flow rate of pressure oil discharged from the lock chamber (20) is controlled by a restricting clearance between the shuttle member (42) and the clamp rod (5). Also, in the initial stage of swing and descend of the clamp rod (5), the flow rate of pressure oil supplied to the lock chamber (20) is controlled by a restricting clearance between the valve chamber (41) and the shuttle member (42).
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