staff@slashgear.com (Oluwademilade Afolabi)
2024-04-24 11:30:21
www.slashgear.com
The planetary gear set, also known as an epicyclic gear set, is the brain of automatic transmissions, allowing the system to smoothly upshift and downshift while you’re driving. At the core are three main parts– the sun gear in the middle, several planet gears that orbit it, and the outer ring gear, also known as the annulus.
The sun gear, located at the center, is usually hooked up to the engine’s output shaft and spins around its axis. Surrounding it are the planet gears, which loop around the sun gear while spinning on their own axes. These planet gears are mounted on a carrier, which is typically all connected to the transmission’s output shaft. The ring gear, which is the largest gear with inward-facing teeth, meshes with the planets and sends power to the wheels.
Automatic transmissions can get a wide range of gear ratios and speeds by selectively engaging different combinations of the sun gear, planet gears, and ring gear. This is done through a series of clutches and brakes that control which parts of the gear set are free to rotate or are held stationary. How these gears are arranged and controlled determines whether the output turns in the same direction as the input (for forward gears), goes in reverse, or spins at a different speed for various gear ratios. This allows the vehicle to have multiple speed settings, or gears, that can be utilized based on the driving conditions.