ABSTRACT
Automatic transmissions for automotive applications fall into three main types: conventional automatic transmissions with multiple gears, belt-type continuously variable transmissions (belt-CVTs), and toroidal CVTs. Conventional automatic transmissions have been in production for more than 60 years. Belt-CVTs have been used in small-scale (e.g., small cars and snowmobile) applications for some time, while both belt-and toroidal CVTs have only in the last few years entered into automotive production. Initially, all fluids for conventional automatic transmissions were based on mineral oils but fluids based on synthetic bases were later developed. By contrast, only synthetic fluids were found to be more effective for CVTs.
