| 摘要 |
PURPOSE:To cause a gate to fall down under its own weight by turning off a clutch in case of emergency by a method in which a threaded shaft to support the gate is screwed with a rotary part and an electromagnetic clutch is provided between the upper end of the threaded shaft and the unturnably supporting part. CONSTITUTION:A gate bar 6 at the upper part of a gate 5 is connected with a threaded shaft 7 with a coupler 8 having a thrust bearing 9, and the threaded shaft 7 is screwed with a rotary part 17 through a ball. In this case, the upper end of the threaded shaft 7 is so designed that a state that a vertically movable supporting part 13 is integrally connected with a guide 15 by an electromagnetic clutch 13 and a state that they are in relatively rotatable state can be switched to each other. To vertically move the gate 5 in usual case, the clutch 16 is turned ON and a motor 21 is operated while regulating the rotation of the threaded shaft 7, whereupon the rotary part 17 turns through gear mechanisms 18 and 19 and the threaded shaft 17 moves vertically. In case of emergency, the clutch 16 is turned OFF, whereupon the threaded shaft goes down while turning under the weight of the gate to shut out the opening 2a rapidly. |
