A wire rope hoist, also known as a block and tackle, consists of a single rope running between two sets of sheaves in a large block, increasing lifting force. Originally made with wooden blocks and hemp rope, modern versions use metal blocks and nylon rope. The hoist can be used for vertical lifting and horizontal clamping. However, the higher the lifting power, the slower the lifting speed, and using an animal to pull the rope can create space problems.
A wire rope hoist is often referred to as a block and tackle and consists of a single rope that is run multiple times between two sets of sheaves in a large block, each of which is typically fitted with a steel hook. As the free end of the rope is pulled, it passes through the set of steps on the two pulleys. Passing the rope through the pulley system increases the lifting or pulling force of the wire rope hoist while keeping the pulling force required to lift the weight very low. Originally made with wooden blocks and pulleys working in concert with hemp-type rope, modern versions often use metal blocks complete with plastic pulleys and nylon rope.
Long before electric hoists, when a heavy object required lifting, a rope was the tool of choice. Occasionally, the object was so heavy that a rope was tied to a horse or mule to provide the pulling force needed to lift the object. Eventually, the hoist, or wire rope hoist, was invented, and lifting heavy objects became much easier. By passing the rope back and forth between the two blocks over a set of stacked sheaves, the lifting power is greatly increased. The more passes the rope makes, the greater the lifting force of the wire rope hoist.
The only problem with the wire rope hoist is that the higher the lifting power of the hoist, the slower the lifting speed. With large blocks and tackle, the load is often lifted only a small amount from each long pull of the rope. This can create time consuming lifting if you are moving a very heavy object. By attaching the free end of the hoist to a horse or mule, the load is lifted easily; however, the animal may have to walk a long distance to complete the lift. This can often create a space problem if there is not enough room for the pet to travel.
In addition to vertical lifting, the wire rope hoist can also be used very effectively to clamp two objects together on a horizontal application. This is often useful when tying two posts together or when trying to straighten a leaning post or barn lumber. A wire rope hoist was often used to lift a section of wall into place during the construction of a barn or other large structure. This technology allowed a wall to be built on the ground and then hoisted into place by passing the wire rope hoist up and over a beam and pulling the rope with a mule or horse.
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