A wire rope hoist is a device used to lift and move heavy objects by using a wire rope, or cable, attached to a moving pulley. A hook is affixed to the end of the cable, and it is used to grapple onto an item to be lifted. The pulley is attached to a motor, which is operated using a hand control unit. The wire rope hoist moves an object by turning the pulley, which wraps up the cable. Many types of hoists will feature a trolley system that allows the pulley and motor to move along a track, thereby making movement of heavy items even easier.
Common in factory or warehouse settings, the wire rope hoist is designed to lift exceptionally heavy objects that a fiber rope would not be able to handle. Each machine is rated for a certain weight capacity, which means only certain types of objects will be able to be moved safely by the wire rope hoist. The thickness of the wire as well as the size of the motor and the materials used for the trolley system will dictate the capacity of the machine.
Sometimes extra pulleys are placed along the length of the wire to further distribute the load of the lifted object. This will reduce the amount of strain directly placed on the wire rope hoist motor, and it will usually increase the weight capacity of the machine. Adding pulleys can increase the amount of friction on the system, meaning the motor may begin to strain if too many pulleys are added. The main pulley is usually primarily responsible for lifting duties, and it is often much larger than other pulleys in the system.
The other end of the cable, without the hook, is usually secured to a fixed point, then wound through the pulley several times to allow for flexibility of movement. This fixed point is usually on the housing of the trolley unit, though stationary units will not have a trolley and the cable can therefore be affixed to the ground, to a beam, or any other fixed point. The operator of the machine can feed or retract the cable as necessary using a hand control unit; the user of the wire rope hoist will generally walk next to the item being moved to monitor its progress and adjust the cable as necessary, though standing too close to the load can be dangerous. The operator should be trained in the proper use of the hoist before attempting to move a load.
By Dan Cavallari