IC engine starter motor pinion drive - starter relay acts as pre resistance to motor winding to prevent pinion and starter ring damage

摘要

Pinion engagement relay has an engagement winding which acts as a pre-resistance for the starter motor field and armature windings. The resistance is so chosen that on actuating the starter switch, the starter motor turns relatively slowly to produce just sufficient torque to turn the starter pinion, the main current switch to the starter motor remaining open. The engagement relay simultaneously pulls the pinion level against the return spring to engage the pinion with the starter ring. Should the pinion fail to mesh, the engagement thrust ring strikes the free wheel cover and prevents the main motor switch from closing until the starter pinion fully engages with the starter ring. A diode prevents a reverse current flow to the engagement relay winding from the main switch.