A transmission (also known as a gearbox) is a mechanism designed to alter the rotational speed and torque output from an engine; it achieves this by adjusting the transmission ratio between the input and output shafts, either to a fixed value or in discrete steps (gears). A transmission consists of a gear-shifting mechanism and a control mechanism; some vehicles also incorporate a power take-off (PTO) mechanism. The gear-shifting mechanism typically employs standard gear trains, although some systems utilize planetary gear trains. Standard gear-shifting mechanisms generally incorporate components such as sliding gears and synchronizers.
On April 12, 2026, the launch ceremony for the group standard *Evaluation Specifications for Maintenance Skills of Automotive Automatic Transmissions* was held in Xianghe, Hebei.