Electric chain hoists consist of an electric motor which turns multiple gears. A chain is placed along the teeth of these gears, so that once the motor begins to run, the chain will be lifted or lowered, depending on the direction of the motor. Typically, a lifting hook is attached to the chain which can be attached to the objects being lifted.
Most other hoists utilize cables instead of chains. Whereas a cable can be wrapped or wound around a spool, a chain cannot be reliably wound or unwound in this way. Therefore, these electrical hoists must use an extra length of chain to allow the hooked end to reach the ground while keeping some chain engaged in the gears. When the hoist rises up, this excess chain then runs out the back of the hoist and lowers to the ground. However, devices called chain falls can be attached to the hoist to get rid of the surplus chain end while improving lifting capacity. These devices operate much like a block and tackle for rope hoist systems, but accommodate the shape and structure of chains.
Chain hoists offer many benefits. First, metal chains are more durable than rope. In addition to their durability, roller or link chain hoists are popular because they are fairly simple and inexpensive. They also require a low level of maintenance and are able to survive high temperatures without suffering damage. In industrial settings, chain hoists are most often used to lift items vertically. Chain hoists are available in multiple varieties; they differ by diameter, load capacity, line material, length, and maximum loaded line speed. Choosing the hoist that fits the needed specifications is important, because safety issues can arise if hoists are misused.