| 摘要 |
PURPOSE:To obtain a high reduction ratio by arranging first and second internal gears closely to and concentrically with each other and by providing the inner peripheral part of said internal gears with planet gears revolving round the rotating shaft and also on its axis. CONSTITUTION:When the motor rotating shaft 2 of a drive motor housing 1 is borne by bearing parts 3 to revolve with a rotating torque Tm and the number of revolutions Nm, a planet gear 9 provided at the eccentric position of a rotating input member 5 revolves round the rotating shaft also with the number of revolutions Nm and on its axis with the number of revolutions Nb in the opposite direction by the interaction between said planet gear 9 and a first internal gear 4 fastened to the housing 1. Also, a second internal gear 7 revolves in the same direction as the rotating input member 5. In this case, if the numbers of teeth of the first and second internal gears 4 and 7 are Za and Zb respectively, the number of revolutions Nb of the planet gear 9 on its axis is (1-Za/Zb)Nm. Thus, a large reduction ratio can be obtained by selection of the numbers of teeth Za and Zb.
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