The principal clutch is a complicated kind of centrifugal clutch and is typically mounted on the output end with the engine crankshaft. The clutch has two sheave faces; one which is laterally fixed (stationary sheave), and one which can shift out and in to engage the belt (moveable sheave). https://martinijihe.laowaiblog.com/31455096/helping-the-others-realize-the-advantages-of-cvt