Ball bearing and method of assembling the same

摘要

A ball bearing includes a rotary member, an outer ring, and a plurality of balls. Part of the rotary member serves as an inner ring. The outer ring is fitted on an outer circumferential portion of the inner ring. The plurality of balls are incorporated in ball holding grooves between the inner and outer rings. At least one of the inner and outer rings has a stepped portion in a circumferential surface thereof close to the ball holding grooves. The stepped portion prevents positional shift of the balls incorporated through a gap between the inner ring and the outer ring set eccentric with respect to the inner ring. A method of assembling a ball bearing is also disclosed.