noun
planetary gear; planetary wheel
Mechanical engineering term for a gear system consisting of a central sun gear, planet gears, and a ring gear.
遊星歯車機構は自動車のトランスミッションによく使われる。
Planetary gear mechanisms are often used in automobile transmissions.
Compound of 遊星 (planet) and 歯車 (gear), referring to the planet-like motion of the gears around a central sun gear.