| 摘要 |
PROBLEM TO BE SOLVED: To secure durability of a roller by regulating a maximum value of tensile stress acting on an inside diameter of a roller according to rotation of a cam shaft to a specified value or below. SOLUTION: This device is fixed to a member receiving movement of a cam 2 such as a locker arm 3 in a state that a shaft 5 is laid between a pair of supporting wall parts 4, 4. Around this shaft 5, a bearing steel roller 6 such as an SUJZ is freely rotatably supported via a radial roller bearing 9. A maximum value of tensile stress acting on an inside diameter part of the roller 6 is regulated to 25 kgf/mm2 or below according to rotation of a cam shaft 1. Therefore, generation of damage of a crack can be prevented in the roller 6 before an engine reaches a maximum life (about traveling distance 2 million km). Because this maximum value is quantitatively regulated, a design by which sufficient durability can be secured can be easily performed.
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