| 摘要 |
PROBLEM TO BE SOLVED: To reduce an eccentric wear and enlarge an axial rigidity by making the carvature radius of the track groove of a first track race having a single arc shape within the specific range of the ball diameter of a rolling body. SOLUTION: In a three point contact ball bearing B, the track groove surface 13a of an outer race 13 receiving a static load is made by a single arc section shape consisting of a radius Re, while the section shape of the track groove surface 12a of an inner race 12 receiving a rotary load is made by a Gothic arch shape contacted to a ball 14 by a rest angleβ. The carvature (Re/Da) of the track groove of a first track race having the single arc shape is made into a range from 50.3% to 53.3% of a ball diameter Da. In this case, it is further favorable to make into the range from 50.5% to 50.0% of the ball diameter Da. Then, the eccentric wear by a spin can be reduced and the axial rigidity can be enlarged than a deep groove ball bearing.
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