What kind of transmission requires no driver input to change forward gears in normal driving?

An automatic transmission changes forward gears without driver input during normal driving. The driver typically selects a driving range and controls speed with the accelerator, while the transmission chooses suitable ratios itself.

Traditional hydraulic automatics use planetary gearsets, fluid pressure, and internal clutches or brake bands. A torque converter connects the engine to the transmission and allows the vehicle to remain stopped in gear without a manually operated clutch pedal. Modern systems commonly use electronic sensors and a transmission control unit to consider vehicle speed, engine load, throttle position, and other inputs.

The first mass-produced automatic transmission was General Motors’ four-speed Hydramatic, introduced in 1939. Earlier systems, including preselector gearboxes and semi-automatics, reduced clutch or shifting work but still required the driver to select or trigger some changes. That distinction explains why “automatic” is the best answer here: a preselector gearbox is still fundamentally a manual transmission, even though it simplifies shifting.

Dual-clutch and automated-manual transmissions can also operate automatically, but they are designs or categories that may be described separately. “Automatic transmission” remains the standard broad answer.