摘要 |
A first piston (22) of a first locking cylinder (20) descends when a pressure of compressed air in an actuation chamber (23) has exceeded a pressure for locking commencement (P1) and ascends by a first spring (24) when the pressure of the compressed air has decreased to a pressure for releasing commencement (P2). A second advancing and retreating cylinder (32) comprises an inlet chamber (41) and an outlet chamber (45) formed below and above a second piston (35), respectively, and a second spring (46). The actuation chamber (23) communicates with the outside air through the outlet chamber (45). A restricting passage (37) is provided in a route between the actuation chamber (23) and the outside air. The actuation chamber (23) communicates with one of the inlet chamber (41) and the outlet chamber (45) through a communication hole (62). |