CVTs

A continuously variable transmission (CVT) is a type of automatic transmission that can change through a continuous range of gear ratios rather than discrete fixed gears. By letting the engine run at its optimal speed across a broad range of vehicle speeds, CVTs aim to improve fuel efficiency, acceleration feel, and ride smoothness.

Most CVTs use a belt or chain that runs between two variable-diameter pulleys. Each pulley consists of opposing halves whose separation changes, altering the effective radius. A control system—often hydraulic, electric, or mechanically actuated—adjusts the pulley faces, while the belt transmits torque. Some CVTs use hydrostatic or electric drive concepts, or integrate a torque converter in the layout.

Common varieties include belt-driven CVTs in passenger cars and scooters, and chain-driven CVTs in some motorcycles. Hydrostatic CVTs, which use hydraulic pumps and motors, are widely used in tractors and other heavy equipment. There are also more specialized CVTs that combine gears with variable-pitch pulleys in industrial machinery.

Advantages of CVTs include smooth acceleration, the ability to keep the engine in its most efficient speed range, and potential fuel economy improvements in urban driving. Limitations can include belt wear, limited torque capacity for high-performance applications, higher manufacturing cost, and noise at certain loads. Some drivers perceive a lack of shift feel compared with traditional stepped transmissions.

CVTs have been used for decades, with early experiments in the 20th century and more widespread automotive use from the late 20th century onward. They are common in small cars, many hybrids, scooters, and various types of industrial machinery.