| 摘要 |
The system for lifting a load comprises two parts which are mobile w.r.t. each other in the vertical direction. The lifting may be achieved by use of two motors, each arranged to drive a shaft over which a supporting rope or cable passes. The two motors are mounted in such a way that their reaction torques when loaded act in opposite directions on a common lever or push-rod device.The lever is normally held in its rest position by the opposing forces to two pre-tensioned springs. In the event of failure, such as the breakage of one cable, the reactions provided by the two motors differ and the lever is consequently moved. The movement of the lever activates an alarm
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