Automatic Transmission

An automatic transmission is a style of transmission where the changing of gears takes place without actions of the driver. An automatic transmission has a torque converter in place of a clutch. The gears in an automatic transmission are arranged in a planetary gear set formation. Transmission fluid generates hydraulic pressure. As the vehicle speed increases, the pressure builds and rate at which the fluid flows through the transmission changes. The gears that are engaged depend on the pressure of the transmission fluid. At higher pressures, or faster speeds, the higher gears are engaged. At lower pressures, the lower gears are engaged. A control lever exists in automatic transmission that allow the driver to select the mode of driving rather than the gears. The modes include drive, reverse, neutral, and some variations on drive.