Transmission (mechanical device)

Drivetrain transmitting propulsion power / From Wikipedia, the free encyclopedia

A transmission (also called a gearbox) is a mechanical device which uses gears to change the speed or direction of rotation in a mechanical device.[1][2] Many transmissions have multiple gear ratios, but there are also transmissions that use a single fixed gear ratio.

Hydraulic automatic transmission (cutaway view)
Epicyclic gearing diagram, as used in hydraulic automatic transmissions

Most currently-produced passenger cars with petrol or diesel engines use transmissions with 5-8 forward gear ratios and one reverse gear ratio. Electric vehicles typically use a single-speed or two-speed transmission.