| 摘要 |
PROBLEM TO BE SOLVED: To prevent lowering sudden and large causing unacceptable danger to a human or an object even when a load is in an any position by adjusting maximum torque generated by a lifting driving device for lifting a load to be small compared with the stopping torque of a brake system. SOLUTION: An asynchronous motor 1 drives or brakes a rope drum 3 via a transmission 2, and a load 5 is suspended on the rope 4 of the rope drum 3. The rotational speed gauge 6a of a pulse generator 6 is connected to the asynchronous motor 1, and the pulse 7 of the rotational speed gauge 6a is led to a rotational speed controller 9 via a first control line 8. A brake 11 for the asynchronous motor 1 is connected to this rotational speed controller 9 via a second control line 10. Compared with the stopping torque of this brake, maximum torque generated by a lifting driving device for lifting a load is adjusted to be small. |
