| 摘要 |
When an inner ring portion of a tripod is brought into contact with a protruding portion, the inner ring portion is brought into contact with the protruding portion because an outer diameter of the protruding portion is smaller than a diameter of a tilted outer end portion of the inner ring portion. Since the inner ring portion is tilted with respect to an axial direction, the inner ring portion is brought into contact with the protruding portion by a point (a line) not by a surface. If the inner ring portion is brought into contact with the protruding portion by the point, a stress concentration is generated at the point with which the protruding portion is brought into contact, a small impact force overcomes a breaking load of the protruding portion in the stress concentration portion, and the stress concentration portion is easily broken (plastically deformed). Accordingly, it is possible to easily break the protruding portion, and even if there is a dimensional error of the protruding portion or the like, it is possible to make a load breaking the protruding portion approximately constant.
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