DRIVE REDUCTION GEAR AND IMAGE FORMING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a drive reduction gear and image forming apparatus, which can extend life of a sun gear and planetary gears at the final stage of a planetary gear mechanism.

SOLUTION: The drive reduction gear includes a plurality of planetary gear mechanisms each including: a sun gear; an inner gear arranged coaxially with the sun gear; a plurality of planetary gears arranged in the inner gear at equal intervals in a circumferential direction and meshing with the sun gear and the inner gear; and a carrier rotatable coaxially with the sun gear and the inner gear to rotatably support the planetary gears. A pitch circle diameter of the sun gear of the planetary gear mechanism in the last stage arranged at the extreme downstream in a drive transmission direction is larger than the pitch circle diameter of other planetary gear mechanisms.

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