What Is a Rope Hoist?
A rope hoist is often referred to as a block and tackle and is comprised of a single rope being run several times between two sets of pulleys in a large block, each of which is typically fitted with a steel hook. As the loose end of the rope is pulled, it passes through the series of steps on the two pulleys. The passing of the rope through the pulley system increases the lifting or pulling power of the rope hoist while keeping the pulling force required to lift the weight very low. Originally manufactured with wooden blocks and pulleys working in concert with a hemp-type rope, modern versions often use metal blocks complete with plastic pulleys and nylon rope.
Long before electric hoists, when a heavy item required lifting, a rope was the tool of choice. Occasionally, the item was so heavy that a rope was tied to a horse or mule to provide the pulling power required to lift the object. Eventually, the block and tackle, or rope hoist, was invented and lifting heavy objects became much easier. By passing the rope back and forth between the two blocks on a series of stacked pulleys, the lifting power is greatly increased. The more passes the rope makes, the greater the lifting power of the rope hoist.
The one problem with the rope hoist is that the more lifting power the hoist has, the slower the lifting speed. With large block and tackle units, the load is often lifted only a small amount from each long pull of the rope. This can create a time-consuming lift if moving a very heavy object. By attaching the loose end of the rope hoist to a horse or mule, the load is easily lifted; however, the animal may have to travel a long distance to complete the lift. This can often create a space problem if there is not sufficient room for the animal to travel.
Besides vertical lifting, the rope hoist can also be used very effectively to tighten two objects together on a horizontal application. This is often useful when tying two posts together or when attempting to straighten a leaning post or barn timber. A rope hoist was often used to raise a wall section into position when building a barn or other large structure. This technology allowed a wall to be built on the ground and then hoisted into position by running the rope hoist up and over a beam and pulling the rope with a mule or horse.
Discuss this Article
Post your comments