A7 Starter motor - hair spring?

[Robert Leigh]

I think at that time the idea was that the increasing speed of the flywheel when the starter disengaged would push the pinion back along the scroll and the spring steel parking spring would hold it until the next time the motor was energised, when the motor would obviously turn faster in relation to the then stationary flywheel . It all relies on the inertia of the parts involved.