The figure shows the vacuum clutch system. This sort of clutch utilizes the existing vacuum inside the engine manifold to operate the clutch. The vacuum clutch consists of a reservoir, non-return valve, vacuum cylinder with piston, and solenoid valve.  During operation, the clutch can deliver heat resulting from frictional drive, https://clutchkereta08631.onzeblog.com/33051480/clutch-kereta-fundamentals-explained