| 摘要 |
PROBLEM TO BE SOLVED: To provide a retainer for a ball bearing, which retainer can improve the response of the bearing for swivelably supporting the swing arm of a hard disk driving device in a minute swivelling state by reducing the mass of the retainer, and further to provide a ball bearing and a hard disk driving device using the same ball bearing. SOLUTION: The retainer for the ball bearing is defined by an annular base portion 41, a plurality of connecting portions 43 which are equidistantly formed in the circumferential direction of the base portion, and include pockets P capable of rollably holding rolling elements 30, the pockets being equidistantly arranged so as to project from one side face of the base portion in the axial direction over the circumference, and nail portions 44, 44 projecting from the axial end portions 43a of the connecting portions. In this case, the positions of the axial end portions of the connecting portions are set so as to be located at the nearer position than the other side face 46 opposite to the one side face than the position of the P.C.D (Pitch Circle Diameter) of the pockets, the P.C.D being formed by connecting the centers P1 of the respective pockets in the circumferential direction. COPYRIGHT: (C)2008,JPO&INPIT
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