The main clutch is an advanced method of centrifugal clutch and is usually mounted for the output end in the motor crankshaft. The clutch has two sheave faces; one which is laterally set (stationary sheave), and one that can move in and out to interact the belt (moveable sheave). https://cvt11864.blogzet.com/not-known-details-about-gearbox-cvt-47184294