Clutch

Actually the pressure plate is bolted to flywheel and clutch disc is held in place from pressure from pressure plate see picture. In picture it says clutch cover, but that is pressure plate.

There are four parts that make up a common clutch unit. The flywheel that attaches to the engine crankshaft, then a clutch disk that has a splined coupler which slides on the transmission input shaft, the pressure plate which bolts to the flywheel and the throw-out bearing.