Electric power steering apparatus

摘要

An electric steering apparatus comprises an annular tooth portion and a metal boss portion fitted in the inside of the annular tooth portion. The annular tooth portion has teeth for engaging with a worm. The annular tooth portion is made of synthetic resin material mixed with fibers having a length with an aspect ratio between 100 and 800 so that the fibers are arranged preferably in a direction crossing the direction of the torque, which is applied to the teeth, thereby to heighten a fatigue strength of the teeth and the teeth root portions.