What Is the Purpose of a Solenoid? (With Video)

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.