| 摘要 |
A thrust ball bearing includes an upper case and a lower case. In the upper case and the lower case, annular rings which are formed in the upper case and the lower case, respectively support balls which are rolling elements, and inter-case gaps are formed between the upper case and the lower case in order to reduce sliding resistance and rotational torque. A seal unit is formed on an inner circumferential surface of the lower case. The seal unit is made up of a recess portion which is formed on the inner circumferential surface and a rubber elastic element which is made as a separate element from the lower case and is then fitted in the recess portion. The recess portion is formed into an annular shape along a circumferential direction of the inner circumferential surface.
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