The figure displays the vacuum clutch mechanism. This kind of clutch employs the present vacuum inside the engine manifold to work the clutch. The vacuum clutch is made of a reservoir, non-return valve, vacuum cylinder with piston, and solenoid valve.  But let's follow the topic of cars nowadays! In this https://clutch-plate19741.answerblogs.com/33233806/clutch-plate-for-dummies