The figure exhibits the vacuum clutch system. This sort of clutch makes use of the prevailing vacuum within the engine manifold to work the clutch. The vacuum clutch consists of a reservoir, non-return valve, vacuum cylinder with piston, and solenoid valve.  To know how a clutch performs, it helps to https://clutch-plate20752.ampedpages.com/considerations-to-know-about-clutch-plate-60048319