Half-toroidal traction drive continuously variable transmission for automobile propulsion systems (Traction drive materials, transmission design and efficiency)

Environmental issues such as exhaust emission have simulated the development of a flexible transmission for an engine-vehicle propulsion system. The authors have been researching and developing the rolling-type CVT, continuously variable transmission, of a half-toroidal traction drive for about 14 years. It represents engineering achievement in the fields of heat treatment technology of rolling elements which transmit tangential force at a maximum Hertzian pressure of 2. 7 GOa, and a molecular design technology of synthetic traction fluid which works in the temperature range of MIN30 to 140°C. The paper shows the design principle of rolling element fatigue life and shear strength of traction fluid at high temperature, and discusses the performance of two types of CVTs of a single cavity with 80 kW and a double cavity with 200 kW transmission capacity.