A four-speed manual transmission. Power from the rotating input shaft turns the countershaft (or …—© Merriam-Webster Inc.

System in an engine that transmits power generated by the engine to the point where it is to be used. Most mechanical transmissions function as rotary speed changers; the ratio of the output speed to the input speed may be either constant (as in a gearbox) or variable. On variable-speed transmissions, the speeds may be variable in individual steps (as on an automobile or some machine-tool drives) or continuously variable within a range. Step-variable transmissions, with some slip, usually use either gears or chains and provide fixed speed ratios with no slip; stepless transmissions use belts, chains, or rolling-contact bodies.

This entry comes from Encyclopædia Britannica Concise.
For the full entry on transmission, visit

Seen & Heard

What made you look up transmission? Please tell us what you were reading, watching or discussing that led you here.

Get Our Free Apps
Voice Search, Favorites,
Word of the Day, and More
Join Us on FB & Twitter
Get the Word of the Day and More