Something about ball bearing and parts

According to the present invention, because, on the hemispherical concave surface of the ball supporting member, in addition to the primary small balls contacting the large ball, auxiliary small balls that are smaller than the primary small balls are provided, the primary small balls are not limited in contacting each other, and a state may occur in which the auxiliary small balls are interposed between the primary small balls. In this region, because ample gaps are provided around the primary small balls, contaminants that have penetrated inside accumulate in these gaps. Therefore, it is possible to prevent interference with the rotation of the small balls due to contaminants adhering to the small balls. In addition, it is possible to prevent interference with the rotation of the large ball due to contaminants adhering directly to the largeball bearing and parts or contaminants being interposed