A pulley is a simple machine designed to increase lift strength using a tracked wheel and a cord, rope or chain. These useful devices are applied often in modern-day machinery, with numerous examples of pulleys found in your community. Look for some common pulley-based systems the next time you go shopping, walking or visiting a local school or theater.
Elevators work via a powerful electronic pulley system. In fact, elevators make use of a system of several pulleys and counterweights to provide the lift system with both power and safety. Some building designers like to create designs in which you can see the internal machinery of the elevator; if you find yourself looking at a visible elevator shaft, look for the thick, steel cables sliding through the drums and pulley systems to lift the platform box.
Old-fashioned “wishing well” style water wells are often equipped with a simple pulley system to assist in drawing water (this is not to be confused with turn-crank systems that wrap the rope attached to a bucket around an axle). Well pulleys consist of a mounted wheel onto which is threaded a rope or chain with a bucket attached to one or both ends. The pulley makes the work of pulling up the bucket easier than it would otherwise be for the user.
Most weight-lifting exercise machines make use of pulleys as a way to control the angle at which weights are lifted while keeping the weights themselves in a dedicated location. This makes the process of weight lifting safer and more effective for the user than free weights may be if used improperly.
Construction pulleys are some of the most basic and common pulleys, good for viewing the basic functioning of this simple machine. These pulleys consist of a wheel track that can be raised to great heights, fitted with chains or rope attached to hooks. These pulleys allow equipment to be raised or lowered to workers at construction sites so that they don't have to climb up and down in order to get tools or materials they need.
In theaters, curtains and fly systems operate using a system of multiple pulleys. These pulleys are located high above the stage where the audience cannot see them and operated from the side of the stage to raise and lower curtains and pieces of scenery during a theatrical performance.
About the Author
Lauren Vork has been a writer for 20 years, writing both fiction and nonfiction. Her work has appeared in "The Lovelorn" online magazine and thecvstore.net. Vork holds a bachelor's degree in music performance from St. Olaf College.