| 摘要 |
PROBLEM TO BE SOLVED: To provide a drive device with a reduction gear capable of reducing a manufacturing cost while smooth rotation of a gear is ensured. SOLUTION: A small and long first sun gear and a large and short second sun gear 10 are formed on the shaft, i.e., the output shaft of a hydraulic motor. The second sun gear 10 is engaged with a second planetary gear 12. The second planetary gear 12 is mounted on a boss part 13 axially protruding from the end face wall of a cylindrical housing 1 and rotatably supported through a ring 14 and a needle bearing 16. A crowing part 14' with a microcurvature is situated on the inner peripheral surface of the ring 14. A boss part 13 having cantilever structure is bent by a torque reaction force but through contact between the outer peripheral cylindrical surface of the boss part 13 and the inner peripheral curved surface of the ring 14, uneven contact is prevented from occurring and a gear is smoothly rotated.
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