A synergistic safety system is incorporated in a crane driven by a high-speed motor which requires both an energy-absorbing torque- limiting device in the speed reduction unit and a drum emergency holding device. The energy-absorbing torque-limiting device transmits the static and dynamic torque required to rotate or hold the drum against the maximum carried load, but will slip at a pre-determined setting to absorb high- speed rotational energy of the drive train and/or torque of the drive motor in the event a two-blocking, load hang-up, overload, or engagement of the drum emergency holding device occurs. The drum emergency holding device is set automatically when the energy-absorbing torque-limiting device is actuated and/or any drive train component fails, which are detected by one or more sensing sub-systems.
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