| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic actuation device capable of surely returning a piston to an initial position.SOLUTION: A hydraulic actuation device has a change-over valve 40 for switching a communication state of a first cylinder chamber 14A and/or a second cylinder chamber 14B with an oil discharge passage 12. In normal operation, the change-over valve 40 operates to communicate the second cylinder chamber 14B with the oil discharge passage 12 and to shut off communication between the first cylinder chamber 14A and the oil discharge passage 12 when a piston 8 is moved toward the second cylinder chamber 14B, and operates to communicate the first cylinder chamber 14A and the second cylinder chamber 14B with the oil discharge passage 12 when the piston 8 is moved toward the first cylinder chamber 14A, and the change-over valve 40 operates to communicate the first cylinder chamber 14A with the oil discharge passage 12 and to shut off the communication between the second cylinder chamber 14B and the oil discharge passage 12 so that the piston 8 is moved toward the first cylinder chamber 14A when the piston 8 does not return to the first cylinder chamber 14A side by energizing force of a return spring 23. |
