| 摘要 |
A planetary reduction gear comprising pairs of partial planetary gears, two partial internal gears and a sun gear or comprising pairs of partial planetary gears, two partial sun gears and an internal gear in which partial planetary gears mesh with partial internal gears or with partial sun gears independently. One of the partial gears is fixed to the input shaft or to the casing. The other partial gear is loosely connected to the input shaft or to the casing by a spiral coupling which allows the partial gear to move in spiral direction. A pressing means pushes the partial gear in the axial direction. Force of the pressing means moves the partial gear in the spiral direction. The partial gear slightly rotates relatively to the other partial gear. Relative rotation of the partial gears cancels backlashes. In the case of helical gears, the spiral coupling can be replaced by an axial coupling. The loosely coupled partial gear can rotate by a cam device comprising tapered keys and axial notches of the partial gears. Axial displacement of the gears themselves or the keys induces relative rotation which cancels transmission error and alleviates noise generation by eliminating backlashes.
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