HALF-TOROIDAL TRACTION DRIVE CONTINUOUSLY VARIABLE POWER TRANSMISSIONFOR 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. Th e authors have been engaged in research and development of a half-toro idal 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 transmissi on efficiency. This paper focuses on the fatigue of traction rolling e lements, endurance of high-temperature fraction fluids and efficiencie s of single- and dual-cavity CVTs for 1.5 L and 3 L passenger cars.