| 摘要 |
PURPOSE:To cause a door body to simply fall down even when a hydraulic device fails in operation, by a method wherein a door body is coupled to the rod of the hydraulic device, the hydraulic device is movably coupled to a rotary member, and a driving device for rotating the rotary member is provided. CONSTITUTION:When, as a result of earth entering a hydraulic cylinder 3, a rod 4 is not moved backward into the cylinder 3 and falling-down of a door body 2 is impracticable, a rod 13 is pushed out from a hydraulic cylinder 12 through operation of other hydraulic device C. Thereafter, the forward end of a rotary member 6 is pushed up through extension of the rod 13, the rotary member 6 is pivoted about a pin 8 counterclockwise, the door body 2 is brought into a fall- down state by means of a water pressure P, and a hydraulic device A is moved to the upper rear. |
