In short, the solenoid is the part responsible for starting the car between the ignition and the engine. The device receives a large current of electricity from the battery of the vehicle as well as a small electric current from the ignition when you turn the key. When the key is turned, the starter solenoid closes two contacts that relay the electric current to the starter motor that will start the engine itself. The threaded terminal on the side of the connects it to the battery. They are connected by a heavy cable. On the other end, there is a link inside the metal housing that engages the pinion on the motor.
The starter motor is a compound, series, or permanent magnet electric motor with the solenoid mounted to it. Low current power is transferred from the starter battery to the solenoid through the key operated switch in your vehicle.
All modernized starters rely on the solenoid which engages the starter drive using the ring gear on the flywheel. The solenoid gets energized and moves a lever or plunger that makes the pinion mesh with the ring gear. The opinion is necessary because it uses a one-way clutch so that when you start the engine and run it, it won’t try to drive the starter motor at an excessive RPM. If a starter doesn’t get enough power from the battery, it will be unable to start the engine, and you may hear a fast clicking sound. This lack of power usually means you have a low battery, or that it is corroded or has loose connections.
Overview of the Solenoid
So to recap, the solenoid is a general term for the device that acts as an electromagnet in a car ignition system. This solenoid transmits electricity through metal contacts that brings the parts into a position to make a full circuit. The starter will receive a tiny electric current when you turn the key in the ignition. The magnetic field produced by the solenoid pulls the contacts, making a full circuit between the battery and the motor. This is essential to any cars starting system. Without this necessary device, you would not be able to start your vehicle.
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