| 摘要 |
PROBLEM TO BE SOLVED: To reduce a work executing cost by a method wherein a limit switch to detect the full closing state of an expansion contraction gate is eliminated through cut-off of energization through detection of the overload of a drive motor and a wiring work pertaining to the limit switch is eliminated. SOLUTION: A push-pull chain 110 is inserted in a bellows type tube cover 111 arranged at the lower part of a door gate constitution body 101, and through engagement of a sprocket 112 in a fixed stay 102, the gate constitution body 101 is expanded and contracted through rotational drive of a motor M. When a free end frame 106 of the gate constitution body 101 makes contact with a door collision stay 103 during closing operation of the gate, the motor M is brought into an overload, which is detected by an overload detecting circuit to cut off energization. Thus, a need for a limit switch to detect the full closed state of the gate is eliminated and a wiring work following arrangement of the limit switch is eliminated. Further, since for detection of a full opening state, a switch body is arranged and a dog is arranged on the gate constitution body 101 side, a wiring work only on the fixed stay 102 side suffices for a wiring work. |
