A power hoist is a device used for lifting and moving heavy objects using a pulley system that is turned by a motor. The specific design of the power hoist can vary, but all of them will include a motor of varying size to turn a pulley that will control a cable, chain, or belt. This cable will attach to the items to be lifted, and when the motor turns the pulley, the cable will retract, lifting the item off the ground. Some hoists are mounted to trolleys that travel along a ceiling-mounted track to make moving the items far easier.
The amount of pulleys used in the power hoist system will vary according to the design of the system. Sometimes the power hoist features only one pulley, around which the cable is wrapped numerous times. As the motor turns the pulley in one direction, the cable is fed out so it can be attached with a hook to the item to be lifted. When the motor turns the pulley in the other direction, the cable is retracted and the item is lifted. The hoist will be rated for a certain weight capacity, meaning only items below that capacity can be lifted and/or moved safely.
A power hoist mounted to a trolley will usually feature a hand control unit mounted to a long wire that runs to the motor, which is mounted high above the ground on the trolley and track system. The operator can then operate the feed of the cable from the ground and move the power hoist along the track safely from the ground while monitoring the progress of the item being moved. These systems are common in warehouses, factories, and other industrial settings in which large objects are moved regularly.
Additional pulleys are often added to the power hoist system to further spread the load of the items being lifted. This usually means heavier objects can be moved, though again, the operator will need to be sure he or she stays within the weight capacity guidelines outlined by the manufacturer. Exceeding such specifications can not only put bystanders at risk, but it can also damage the machine and potentially void any manufacturer warranties. The hoist will usually be sold with the appropriate number of pulleys that can be used with the system; many manufacturers recommend avoiding alteration of the system in any way.