The figure exhibits the vacuum clutch mechanism. This sort of clutch employs the prevailing vacuum in the motor manifold to operate the clutch. The vacuum clutch contains a reservoir, non-return valve, vacuum cylinder with piston, and solenoid valve.  This stops the transmission shaft and clutch plate from tilting up and https://raymonduvtrn.loginblogin.com/40211144/clutch-plate-can-be-fun-for-anyone