Starter Motor (Typical Example)
(1) Brush assembly. (2) Field. (3) Solenoid. (4) Clutch. (5) Pinion. (6) Armature.
The starter motor is used to turn the engine flywheel fast enough to get the engine to start running.
NOTE: Some starters have starter-to-frame ground straps. But, many of these starters are not electrically grounded to the engine. They have electrical insulation systems. For this reason, the starter-to-frame ground strap may not be an acceptable engine ground. Original equipment starters are electrically grounded to the engine. They have a ground wire from the starter to the negative terminal of the battery. If a starter change is made, consult an authorized dealer for proper grounding procedures for that starter.
The starter motor has a solenoid. When the ignition switch is turned to the START position, the starter solenoid will be activated electrically. The solenoid plunger (core) will now move to push the starter pinion, by a mechanical linkage, to engage with the flywheel ring gear. The starter pinion will engage with the ring gear before the electric contacts in the solenoid close the circuit between the battery and the starter motor. When the circuit between the battery and the starter motor is complete, the pinion will turn the engine flywheel. A clutch gives protection for the starter motor so that the engine cannot turn the starter motor too fast.
When the ignition switch is released from the START position, the starter solenoid is deactivated (current no longer flows through the windings). The spring now pushes the plunger (core) back to the original position, and, at the same time, moves the pinion gear away from the flywheel ring gear.