7.4.10 Overload Protection

Overload protection can and should be built into the winch unit, in particular for power operated types. The most common type of overload protection being the slipping clutch. This can be in the winch winding handle or in the mechanism of the winch. It employs a spring loaded plate which will slip if the applied load exceeds the setting position of the clutch.

Some manually operated winches are fitted with shear pins in the operating handle which will fail if an effort in excess of that designed to operate the winch at SWL is applied. Such arrangements prevent further operation of the winch.

It is a feature of pneumatic motors that they will stall to safety if overloaded, either as the result of the application of a load greater than the maximum design load or if the air supply falls below a level necessary for the motor to operate at the load applied. In certain circumstances, this will result in the motor turning slowly and lowering the load in a controlled manner.

Hydraulic systems are protected by relief valves which prevent the pressure in the system exceeding the design pressure required to lift the SWL.