Sun Gear - Gear Terminology
The external gear attached to the central axis of a planetary gear mechanism is called the sun gear.
The sun gear, together with the planetary gears, internal gears, and planetary carriers that connect the planetary gears, constitutes the main element of the planetary gear mechanism.
When selecting planetary gear mechanisms, the sun gear is used as the input side in the planetary and star type designs, while it is fixed in the solar type design.
