Page 10 - august newsletter
P. 10
August 2020
www.tswfl.org
Starter Motor
`Triumphs Live On
Tech Corner
Return to Start Page 9
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-continued
By way of review, turning the ignition key beyond the 'ignition on' position feeds a current to the solenoid. The ignition switch has a return spring, so that as soon as you release the key it springs back and turns the starter switch off. When the switch feeds current to the solenoid, the electromagnet attracts an iron rod. The movement of the rod closes two heavy contacts, completing the circuit from the battery to the starter. The rod also has a return spring -when the ignition switch stops feeding current to the solenoid, the contacts open and the starter motor stops. The return springs are needed because the starter motor must not turn more than it has to in order to start the engine. The reason is partly that the starter uses a lot of electricity, which quickly runs down the battery. Also, if the engine starts and the starter motor stays engaged, the engine will spin the starter so fast that it may be badly damaged.
The starter motor itself has a device, called a Bendix gear, which engages its pinion with the gear ring on the flywheel only while the starter is turning the engine. It disengages as soon as the engine picks up speed, and there are two ways by which it does so - the inertia system and the pre-engaged system. The inertia starter relies on the inertia of the pinion - that is, its reluctance to begin to turn.
Inertia system
