A starter motor is an electrical device used to start an internal combustion engine. Typically a very low-geared device, the starter motor is able to crank over the much larger engine by virtue of its extreme gear reduction. The starter motor is a part of a starting system consisting of the starter, a starter solenoid and the battery. As the ignition switch is turned, it sends an electrical charge to the starter solenoid. This, in turn, sends the charge to the starter motor that cranks the engine until it starts. Once the engine fires to life, the starter motor clicks off and disengage the starter ring. The typical starter motor is composed of heavy copper wire wound around an armature. This device is placed inside of a heavy steel or aluminium case equipped with electrical brushes that contact the armature and pass the electrical charge to the heavy wire. As the electricity flows through the wire, it causes the armature to spin. A small gear is attached to the output shaft of the armature and moved in and out by means of a Bendix. The Bendix engages the small gear with the starter ring, which turns the engine as the armature turns. T's & C's Apply