Some Methods of Improvement of Dynamic Characteristics of Planetary Gears

Although planetary gears used in an industrial region have load equalizing mechanisms in order to equalize distributed loads on planet gears each other, those mechanisms may be uneffective dynamically in some cases. In this report, the face bearing patterns, the load distributions on planet gears and the dynamic loads on a sun gear in some types of planetary gears have been measured by strain gages in order to obtain an easy method of improving the dynamic characteristics of planetary gears. The planetary gears used in the experiment are those with non-crowned planet gears, those with crowned planet gears and those with either the movable internal gear or the movable sun gear. Consequently results are as follows. Although using crowned planet gears is effective for decreasing the maximum fillet stress owing to improvement of the face bearing patterns, which is uneffective for both equalizing the distributed loads on planet gears each other and decreasing the dynamic load. On the other hand, moving either the internal gear or the sun gear, which is a comparatively easy method, is effective for both decreasing the maximum fillet stress and the dynamic load and equalizing the distributed loads on planet gears.