| 摘要 |
PROBLEM TO BE SOLVED: To provide a four-point contact ball bearing excellent in moment load resistance and moment rigidity and excellent in peeling resistance and burning resistance. SOLUTION: A groove radius of curvature R1 of an inner ring 1 is made 53.0Bd% (more than 52Bd% and less than 53.5Bd%) and a groove radius of curvature R2 of an outer ring 2 is made 55.0Bd% (more than 53.5Bd% and less than 56Bd%) on this four-point contact ball bearing. Consequently, it is possible to secure peeling longevity and moment rigidity without causing shoulder riding of a ball 3 and lowering of burning longevity. Additionally, it is possible to avoid a problem of heating caused by spinning of the ball 3 and shoulder riding of the ball 3 without causing lowering of the moment rigidity.
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