| 摘要 |
PURPOSE:To prevent damage of a locker arm, by a method wherein a trigger valve, which decides whether a motion to release a stopper for controlling movement of a hydraulic actuator for moving a locker arm is started, and when the stopper is released, releasing of the stopper is completed at a stretch. CONSTITUTION:A device is provided with hydraulic actuators 21 and 22 which axially switch and move the locker arm of cylinders, for example, No.4 and No.1, which can be forced into a rest, and the hydraulic actuator 21 has ports 21d-21j formed therein and has the function of a direction switching valve. The movement of the hydraulic actuator 21 is controlled by a stopper 26 selectively engaging with grooves 21k and 21l. In which case, a trigger valve 27, which is opened when an amount of oil discharged from an oil pump 6 exceeds a given value and feeds an oil pressure to an oil pressure chamber 25a, is installed in a line running between the oil pressure chamber 25a of a hydraulic actuator 25 for releasing of the stopper 26 and a switch operating valve 28 located on the discharge circuit of the oil pump 6. |
