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An electrical chain hoist is a device used to lift heavy objects. Consisting of an electric motor driving a set of gears, the chain is placed between the gears of the electrical chain hoist. When the motor is activated and the gears are turned, the chain is pulled up or lowered down, depending on the direction of the motor. In some models of electrical chain hoist, a pair of pulley-like devices known as chain falls are attached to the hoist motor to make the lifting of very heavy objects possible through very little effort from the hoist motor.
The difference between a typical hoist and an electrical chain hoist is that a cable can be wound around a spool, whereas a chain cannot. The electrical chain hoist requires a length of chain equal to the section of chain equipped with the hook to be run out the back of the hoist. This surplus chain allows the hooked end to be lowered to the ground while keeping chain links engaged in the hoist drive teeth. As the hook and object being lifted rise, the surplus chain comes down to the ground. In this design, some hoists actually have a hook attached on each end of the chain, which allows the hoist to be used regardless of which end of the chain is available.
By adding a chain falls to the electrical chain hoist, the loose chain end is eliminated and the lifting capacity of the hoist is greatly increased. A chain falls is very similar to a block and tackle used in rope hoist design with the exception being the chain is in place of the rope. Unlike a block and tackle, the chain falls-equipped electrical chain hoist is not recommended for horizontal pulling. The weight of the chain pulling against the horizontal chain falls may cause a severe tangling problem that could be detrimental to the effectiveness of the electrical chain hoist.
Commonly attached to a set of steel casters or wheels riding on a trolley system or I-beam, the hoist is able to be used to lift and carry heavy objects through a building and even to outside loading docks, providing the hoist is able to receive electrical power. Often, a recoiling power line or a sliding electrical connection is used to allow the electrical chain hoist to be moved throughout a building. The chain hoist is available in several sizes, each rated for a particular lifting capacity.
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