Epicyclic gearing

Three-shaft planetary gearset

An epicyclic gear train (also known as a planetary gearset) is a gear reduction assembly consisting of two gears mounted so that the center of one gear (the "planet") revolves around the center of the other (the "sun"). A carrier connects the centers of the two gears and rotates to carry the planet gear(s) around the sun gear. The planet and sun gears mesh so that their pitch circles roll without slip.

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