Abstract
Measured improvements in fuel economy and emissions mean that the full toroidal traction drive is attracting more attention within the automotive industry as time goes on. There is therefore an increasing demand for information on the design and operating characteristics of this type of CVT. This paper uses an established theoretical technique to study full toroidal variator contact losses and includes an approximation for thermal effects in the contact. Calculation of optimum design traction coefficient is outlined and experimental measurements of variator efficiency are presented. Finally, a simple theoretical model of the dynamics of variator roller steer is used to explain the fundamentals of variator ratio change, the inherent ability to control transmitted torque rather than variator ratio and system response to rapid rates of ratio change.