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What Is the Purpose of a Solenoid?

by Mark Vallet

Solenoids are used in a variety of systems, but most commonly in cars. Starters in particular use solenoids. Often when a vehicle's starter is malfunctioning the solenoid is the problem.

Definition of a Solenoid

Solenoids are a type of electric motor. They are commonly used in cars as heavy duty relays. The technical definition of a solenoid is a device or motor that can produce back and forth, or linear, motion when a force is applied. Solenoids will respond to hydraulic, pneumatic or electrical force.

Solenoids as Actuators in Cars

Solenoids are mainly used in cars as actuators. A solenoid will move a component a certain distance after electricity has been applied. Starters are probably the most common actuator component. Another common usage in vehicles is as a relay. A solenoid closes a circuit when electricity is applied. .

Types of Solenoids

Solenoids can also be used in propane, nitrous-injections and propane systems. Fuel injectors are also solenoid valves. There are different types of solenoids. The push type uses a spring to hold the solenoid closed; it opens when voltage is applied. The pull type pushes out a solenoid arm when electricity is applied. A third type is push/pull, which works in both directions.

Solenoid Mechanics

A solenoid has a coil set that it uses to induce a magnetic field on a permanent magnet. The magnet will either be attracted or repelled when power is applied to the coil. In a car, the solenoid in the starter is a relay which moves metal contacts into place which closes a circuit. The solenoid is sent an electrical current when the ignition key is turned. This triggers the magnetic field of the solenoid that pulls on the contacts, closing the circuit.

About the Author

Mark Vallet is a a stay-at-home dad who began freelance writing in 2009. He has produced online content for Demand Studios, Autos.com and CarsDirect.com. He has traveled extensively within the U.S. and internationally. Vallet holds a Bachelor of Arts in English literature from the University of Iowa.

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