| 摘要 |
PROBLEM TO BE SOLVED: To prevent the wear of a shaft part for rotatably supporting gears, to improve durability by forming a wear resistant film on the surface of the shaft part in a gearing having gears rotatably supported by the shaft part. SOLUTION: This gearing is composed of a sun gear and an internal gear coaxially arranged so as to be relatively rotatable, and a plurality of planetary gears 4 rotatably supported to a planetary frame 3 and meshed with the sun gear and internal gear. Each planetary gear 4 is rotatably supported to a shaft part 5 fixed to the planetary frame 3, through a needle roller bearing 6. In this case, a wear resistant film 7 is formed at least at a part, coming in contact with the bearing 6, of the surface of the shaft part 5. With this constitution, even if lubricating oil break occurs during action, the mutual direct contact of the base materials of the bearing 6 and shaft part 5 is prevented by the presence of the wear resistant film 7 to prevent the wear of the shaft part 5. The wear resistant film 7 is formed of a diamond-like carbon film, for instance, and it is preferable to further form a lubricating thin film formed of a fluorinated lubricant, on the surface.
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