The winch clutch is a dry-disc design. PTO input power is transferred to the upper sprocket by chain. The face of the upper sprocket is machined and has the friction material bolted to this face. This acts as the drive plate. The cable spool end face is machined and acts as the driven plate.
The cable spool slides back and forth along the shaft on FiberGlide bearings. The two are kept apart by 3 cup springs. The clutch actuator is made of 2 steel blocks with 3 decreasing-depth ramps machined into the mating face of each one. Each ramp has a steel ball. One block is held stationary, the other rotates.
Pulling on the engagement rope rotates the inner actuator block. As it rotates, the balls riding in the ramps push it away from the stationary block. This pushes the cable spool along the shaft until it is pushed against the friction pads on the drive plate, which causes the drum to turn. Clutch slippage and burning will result from the rope not being pulled hard enough.
A brake pad riding on the outer rim of the cable spool prevents the drum from spooling out too fast, which would cause tangling of the cable.