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What is the planetary gear set?



The components and function of the planetary gears in automatic transmissions.

The planetary gears are a set of sun gears, planet gears and ring gears inside the automatic transmission. That is why they are called “planetary” gears. Planetary gears produce the gear ratios that your transmission produces and is the main function of the transmission in which everything depends. The entire component is about 10 inches in size and is the main function of the overall transmission.

Think of it as planets rotating with the largest gear on the outside as the ring gear with the core centered in the middle is the sun gear and the small planetary pinions between those two gears rotating around the sun gear is like a solar system - See illustration below. These gears are always engaged and they are all locked together inside one device.

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The sun gear is in the center of them all and the ring gear connects to the planet gears 0- see illustration above. Each gear ratio depends on the state of the planet gears being locked in or unlocked as they move around the “sun” gear.

Each of the planetary pinion gears have a different functions such as delivering torque or speed. The torque convertors are connected to clutch system which is connected to the planetary gear set and feeds pressurized oil into the gears. The propelling movement sends in motion the necessary thrust to the output shaft that turns your automobile's wheels.