WORM WHEEL, SPEED REDUCING MECHANISM, AND ELECTRIC STEERING DEVICE

摘要

PROBLEM TO BE SOLVED: To reduce expansion of a synthetic resin annular tooth part in a worm wheel caused by absorption of humidity for efficiently transmitting a motor output from a worm to the worm wheel. SOLUTION: An outer circumference radius of a projection bar in a metallic core metal part 82 fitted inside the synthetic resin annular tooth part 81 in the worm wheel 8 is set to be approximately equal to a radius of the tooth bottom in the annular tooth part 81 or to be larger than that, and consequently, an absolute quantity of the synthetic resin for the worm wheel 8 is reduced.