Final answer:
An automatic transmission uses both a torque converter and a lever or button to change gears.
Step-by-step explanation:
An automatic transmission uses both a torque converter and a lever or button to change gears.
The torque converter is a hydraulic device that allows the engine to continue running even when the vehicle is stopped or moving at a low speed. It uses fluid coupling to transmit power from the engine to the transmission.
The lever or button is used by the driver to select the desired gear. This can be a physical lever or a button located on the gear selector panel.