A pulley is one of the original simple machines. The pulley was possibly created by Archimedes in B.C. times. Its original use was to lift buckets of water. The term sheave can also be used to refer to a pulley.
The original primary use for pulleys was to make it easier to lift heavy items. The pulley is a simple machine made with a wheel and a rope, cord, or chain.
There are three types of pulleys:
- One has a fixed axle
- One has a moveable axle
- A compound, which is a mixture of the two
Pulleys can be found everywhere to help make tasks easier. In addition to lifting things, pulleys can be used singly or with many pulleys working together in order to transport people or things. They can also be used to provide power from one shaft to another.
Examples of pulleys include:
- Elevators use multiple pulleys in order to function.
- A cargo lift system that allows for items to be hoisted to higher floors is a pulley system.
- Wells use the pulley system to hoist the bucket out of the well.
- Many types of exercise equipment use pulleys in order to function.
- Construction pulleys are used in order to lift and place heavy materials.
- Curtains at a theatre are moved using pulley systems that pull the curtains apart.
- Blinds on windows operate using a pulley system to move the blinds up and down. You pull the cord on the blinds and the pulley system causes the blinds to open or close.
- Flagpoles use pulleys in order to hoist the flag up or to bring it down. You pull the string on the pulley and the flag runs up or down the pole.
- Clotheslines can use pulley systems in order to make it easier to pull clothes toward the user.
- Pulleys can be used to place birdfeeders high in trees or on poles, and then to pull them down when they need to be refilled or removed.
- Roofers may use pulleys in order to hoist all of the shingles up on to the roof instead of attempting to carry them.
- A crane is a type of pulley that is used in construction.
- Engines utilize a pulley system in order to work.
- Fans with chains are utilizing a pulley system in order to be turned on and off.
- A bulldozer is an example of use of a pulley system.
- Pulleys are utilized regularly in oil derricks.
- Pulleys can be used to extend ladders.
- Sails on sailboats are raised and lowered using pulleys.
- Garage doors raise and lower utilizing a pulley system.
- Rock climbers use pulleys to help them to climb.
- Timing belts in cars are examples of pulleys.
- Escalators utilize pulley systems to function.
In all of these examples, a cable system works in order to make lifting easier or to make moving items easier. Pulleys are essential to being able to move and lift very heavy or large items. The simple principle behind pulleys makes these one of the most effective tools in existence.