| 摘要 |
<p>A wedge type locking member (27) is brought into contact with a first piston (12) for clamping by means of a pushing spring (28). Thereby, the first piston (12) is prevented from returning from the clamping position (X) to the unclamping position (Y) . The locking member (27) is provided with two pressure receiving surfaces (F)(S) having substantially equal areas. A fluid pressure within a first actuation chamber (13) for clamping is imposed to these pressure receiving surfaces (F)(S) in the opposed directions. The locking condition of the locking member (27) is cancelled by means of a second piston (39). <IMAGE></p> |
