| 摘要 |
PROBLEM TO BE SOLVED: To provide the subject retainer capable of holding balls having a diameter not less than that of a copper alloy made retainer, and capable of increasing the number of balls in the circumferetial direction. SOLUTION: This retainer 1 is formed in an annular plate shape by injection moding of synthetic resin, and has a spherical pockets 2 retaining balls so that they can roll, at several positions spaced at equal intervals in the circumferential direction. At an opening circumferential edge of each pocket 2, a pair of ball dropping preventing protrusions 3, 3 are provided protrusively to the inward in the diametrical direction of the pocket 2. The protrusions 3, 3 engage with the balls to prevent their droppage, respectively, and arranged apart each other at 180 degrees in the circumferential direction of the pocket 2. An angle between a line L1 connecting the protrusions 3, 3 and a line L2 connecting the center of the retainer 1 to the center of the pocket 2 is set 40-60 degrees.
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