Page 11 - August 2020 Newsletter
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August Return to
2020 `Triumphs Live On’ Start
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Tech Corner-continued
An inertia type starter: this one is an 'inboard' type in which the Bendix gear throws the pinion towards the motor; there
are also 'outboard' ones in which it moves the other way. The pinion is not fixed rigidly to the motor shaft - it is threaded
on to it, like a freely turning nut on a very coarse-thread bolt. Imagine that you suddenly spin the bolt: the inertia of the
nut keeps it from turning at once, so it shifts along the thread of the bolt. When an inertia starter spins, the pinion moves
along the thread of the motor shaft and engages with the flywheel gear ring. It then reaches a stop at the end of the thread,
begins to turn with the shaft and so turns the engine.
Pre-engaged system
In the pre-engaged system, the pinion is moved by the solenoid; there is an initial period in which the motor turns slowly
to allow engagement, so the whole operation is gentler and causes less wear on the teeth.
