Correct Frictional Properties. Thermal and Oxidation Stability. Gears Gears are the muscle of any transmission, whether manual or automatic. Gears transfer torque and power and can provide the vehicle with changes in speed and direction. Planetary gear sets are used as the basic means of transferring or multiplying torque from the engine in an automatic transmission.
Planetary gears offer many advantages over manual slide type gears.
Force is distributed over many teeth for more strength. They are always in mesh and do not have to be shifted to change gears. Therefore, they do not clash like gears going in and out of mesh. Extreme Pressure Properties. The transmission oil pump, driven by the torque converter, generates fluid pressure inside an automatic transmission.