The figure shows the vacuum clutch mechanism. This kind of clutch works by using the prevailing vacuum within the engine manifold to operate the clutch. The vacuum clutch is made up of a reservoir, non-return valve, vacuum cylinder with piston, and solenoid valve.  This helps make the flywheel rotate provided https://garrettblpsw.madmouseblog.com/13503731/5-easy-facts-about-clutch-kereta-described