Solenoid

Internal Solenoid Operation

Solenoids act as electric to mechanical energy converters, taking an electrical signal and converting it to work. The operation is based upon the reaction of a moving element, the armature or plunger, in response to a magnetic field developed by an electrical conductor, usually a winding. Solenoids can be configured to operate in either Direct Current (DC), or Alternating Current (AC). Solenoids are electromechanical actuating devices found in many types of applications.

Solenoid External and Internal Parts

The solenoid switches is the part of automobile which relays a large electric current to the starter motor. The system converts electrical energy from the batteries into mechanical energy to turn the engine over. It is mounted on the starting motor and forms the major component of the starting system. The coils inside the solenoid are energized by electricity, they create a magnetic field which attracts and pulls a plunger. Attached to one end of this plunger is a shift lever. The lever is connected to the drive pinion and clutch assembly of the starter motor.
The solenoid receives a large electric current from the car battery and a small electric current from the ignition switch. As the ignition switch is turned, a small electric current is sent to the starter solenoid. The pair of heavy contacts closes, relaying the a large electric current to the starter motor, which in turn sets the engine in motion.
Once the engine starts, the key-operated switch is turned, a spring in the solenoid assembly pulls the pinion gear away from the mesh, and the starter motor stops. The starter's pinion is clutched to its driveshaft through an overrunning sprag clutch which allows the pinion to transmit drive in only single direction. In this manner, drive is transmitted through the pinion to the flywheel ring gear.