continuously variable transmission

A continuously variable transmission (CVT) (also known as a single-speed transmission, stepless transmission, variable pulley transmission, or, in case of motorcycles, a twist-and-go) is an automatic transmission that can change seamlessly through a continuous range of effective gear ratios. This contrasts with other mechanical transmissions that offer a finite number of gear ratios. The flexibility of a CVT allows the input shaft to maintain a constant angular velocity.