A gearbox, often called a transmission, is a mechanical system designed to manage the rotational output of an engine or motor. Plan of sprocket-and-chain "gearbox" in Benz Patent-Motorwagen, 1886 - 1888. Low gear is from loose pulley 31 through the gears and clutch 36. This allows the next gear to be pre-selected while the current gear is engaged, resulting in very fast and smooth gear shifts. DCTs are commonly found in performance vehicles. This capability allows a power source to. In this detailed guide, we'll break down how a transmission works step by step, explain its main components, compare different types of transmissions, and explore why proper transmission function is essential for performance, fuel efficiency, and longevity.