Starter motor having intermediate gear

摘要

A starter motor includes an intermediate gear engaging with and driven by a pinion connected to an output shaft of an electrical motor. The intermediate gear is coupled to the pinion by means of a retainer to be shifted in its axial direction together with the pinion. The intermediate gear engages with a ring gear of an engine to crank up the engine when it is shifted in the axial direction. The retainer is connected to a pinion boss by forcibly enlarging a resilient opening of its groove, and the resilient opening recovers its original position after the retainer is connected to the pinion boss. In this manner, the retainer is prevented from dropping off from the pinion boss during an assembling process of the starter motor. The retainer is made of resin to have an enough thickness to secure a sufficient mechanical strength.