| 摘要 |
The present invention prevents abrasion that is caused by residual projections (22a) which remain on a circumferential direction end surface of retainer elements (15b) following the breaking off of a small cross section part (17a); the abrasion occurs at a part where the residual projections (22a) come into contact with the end surface which the projections are facing. On one circumferential direction end surface of the retainer elements (15b), in a circumferentially protruding state, a projection (23) is provided with the tip thereof being flat. In a state where the retainer elements (15b) are aligned in the axial direction and the tip end part of the projection (23) and the other circumferential direction end surface of the retainer elements (15b) are in contact to each other, the position, shape, and dimensions of the small cross section part (17a) and the projection (23) are regulated so that a circumferential direction gap (24) exists between the tip end part of the residual projections (22a) and the circumferential direction end surface of the retainer elements (15b). |
