How does a car's transmission work?

A car's transmission transfers power from the engine to the wheels while allowing the engine to operate within its efficient RPM range. The engine produces power at varying speeds, but the wheels need different amounts of torque depending on whether you're accelerating, cruising, or climbing a hill. The transmission uses a set of gears with different ratios to match engine output to driving conditions. In a manual transmission, the driver uses a clutch to temporarily disconnect the engine and manually select gears. In an automatic transmission, a torque converter and a hydraulic or computer-controlled system handle gear changes automatically. Modern continuously variable transmissions use a belt and pulley system to provide a seamless range of gear ratios rather than fixed steps between gears.