The term "electric pulley" can refer to a few different types of pulley systems. Pulleys are systems that use a series of round wheels to move a belt, cable, or other material for any variety of purpose. Automobiles feature pulley systems that guide the timing belt or other belts within the engine compartment, and pulleys are commonly used in industrial settings for a variety of purposes. An electric pulley is one that is powered by electricity, thereby providing the moving force for the entire pulley system. The term may also apply to electric winch systems.
An electric pulley that acts as a winch system is commonly used on off-road vehicles as well as in industrial settings. A winch mounted on the front of an off-road vehicle will feature a long cable that wraps around a pulley, which is motorized to turn the cable quickly or under great strain. This system is used to help pull the vehicle out of mud or other obstacles that may prevent the wheels of the vehicle from turning properly. These winches can also be used in industrial settings to pick up heavy objects and move them across a space. This is common on loading docks, in warehouses, or other settings where a track can be built to allow the entire electric pulley system to move.
Systems that are designed to lift and move heavy objects will feature an electric pulley in two places: the first pulley will do the lifting via a cable, and the other pulley or pulleys will be attached to a track on which the pulley system can be moved to relocate the heavy object. This set of pulleys is known as the trolley. The lifting pulley will allow the cable to pass through it; the cable will be fixed on one end and wrapped around another pulley on the other end. This second pulley is electric powered, and it feeds the cable through the first pulley. The first pulley will rise or drop in accordance with how much cable is being fed through it; the casing of the pulley may have a hook on which items can be secured for lifting.
The trolley is designed to support the pulley system and allow the entire unit to move along a track. This track usually takes the form of an I-beam that is mounted on the ceiling of the warehouse or space, or it is otherwise suspended high in the air to accommodate larger objects.