Semiautomatic transmission

A semi-automatic transmission (also known as a clutch-less manual transmission, auto-manual, automated manual transmission, trigger shift, flappy-paddle gear shift, Manumatic, Tiptronic, Touchshift, Geartronic, Sportronic or paddle-shift gearbox) is an automobile transmission that combines manual transmission and automatic transmission.

It allows convenient driver control of gear selection. For most of automotive history, automatic transmissions already allowed some control of gear selection using the console or shifter, usually to limit the transmission shifting beyond a certain gear (allowing engine braking on downhills) and/or locking out the use of overdrive gears when towing. It enhanced such features by providing either steering wheel mounted paddle shifters or a modified shift lever, allowing the driver to enter a "manual mode" and select any available gear, usually in a sequential "up shift/downshift" manner.

Some transmissions allow the driver to have full control of gear selection, though most will intervene to prevent engine stalling and redlining by shifting automatically at the low end and/or high end of the engine's normal operating range. Hydraulically-coupled and most clutch transmissions also provide the option of operating in the same manner as a conventional automatic transmission, by allowing the transmission's computer to select gear changes. A few also allow an alternate automatic mode, often called "sport" mode, where gear selection is still fully automatic but the transmission will favor higher engine speeds (at which the engine will produce the highest horsepower and/or torque) by up shifting later when accelerating and downshifting earlier when slowing.

A clutch-less manual facilitates gear changes by dispensing with the need to press a clutch pedal at the same time as changing gears. It uses electronic sensors, pneumatics, processors and actuators to execute gear shifts on input from the driver or by a computer. This removes the need for a clutch pedal which the driver otherwise needs to depress before making a gear change, since the clutch itself is actuated by electronic equipment which can synchronize the timing and torque required to make quick, smooth gear shifts. The system was designed by automobile manufacturers to provide a better driving experience through fast overtaking maneuvers on highways. Some motorcycles also use a system with a conventional gear change but without the need for manual clutch operation.

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