Looking at the installation manual, it appears that the clutch uses a standard automotive dry clutch disc with damper springs.
The assembly differs from a car clutch in that it is not spring-engaged; it is spring-released, and engagement is done by means of bobweights on the clutch fingers.
I.e., centrifugal force acts on the "fingers" (the photos don't show exactly how), and as the engine spins faster, the fingers press on the pressure plate, which gradually clamps down on the clutch disc that is trapped in the space between the flywheel and the pressure plate. As engine speed decreases, the force applied by the fingers is reduced, and at some point is overcome by the light springs shown in the loose pressure plate picture, so the pressure plate moves away from the clutch disc, and the prop is effectively disengaged from the engine..
Mike Halloran
Pembroke Pines, FL, USA