摘要 |
A first piston and a second piston are accommodated in a piston chamber of a cylinder. The first piston is connected to a main valve member which opens and closes a main flow passage. The second piston is connected to a second rod having a stopper whose position can be adjusted. Pressure fluid is supplied to the second pressure chamber to move the second piston forward to a position where the stopper abuts against the abutting portion. In this state, pressure fluid is supplied to the first pressure chamber to move the first piston to a position where the first piston abuts against the second piston, thereby opening the main valve member by a stroke of the first piston.
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