Transmission (mechanical device)
Drivetrain transmitting propulsion power / From Wikipedia, the free encyclopedia
For other uses of the word "transmission", see Transmission.
"Gearbox" redirects here. For other uses, see Gearbox (disambiguation).
A transmission (also called a gearbox) is a mechanical device which uses a gear set—two or more gears working together—to change the speed or direction of rotation in a machine.[1][2] Many transmissions have multiple gear ratios, but there are also transmissions that use a single fixed-gear ratio.
Most currently-produced passenger cars with gasoline or diesel engines use transmissions with 5–8 forward gear ratios (also called speeds) and one reverse gear ratio. Electric vehicles typically use a fixed-gear or two-speed transmission with no reverse gear ratio.