Half-Toroidal Traction Drive Continuously Variable Power Transmission for Automobiles : Traction Drive Materials, Transmission Design and Efficiency

A continuously variable power transmission, CVT, has the potential to provide comfortable cruising, powerful acceleration, fuel economy and improvement of exhaust emission as an automotive propulsion system. The authors have been engaged in research and development of a half-toroidal traction drive CVT since 1980. In practical use, reliability and compactness are important issues, which motivate ceaseless improvement of traction drive materials, synthetic traction fluids and transmission efficiency. This paper focuses on the fatigue of traction rolling elements, endurance of high-temperature traction fluids and efficiencies of single- and dual-cavity CVTs for 1.5 L and 3 L passenger cars.