Planetary Gear Drive

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A planetary gear is a type of epicyclic gear system comprised of spur gears. In planetary gearing (also known as epicyclic gearing), a center gear, called a sun gear, serves as the input and driver of the set. Three or more “driven” gears (referred to as planets) rotate around the sun gear within a planetary gearbox. Finally, the planets engage with a ring gear from the inside, which makes an internal spur gear design. Because the planet gears are evenly distributed around the sun gear, planetary gear trains are known to be extremely rugged designs. Another benefit of a planetary gearset is that it is easy to convert to a different ratio by simply changing out the carrier and sun gears.