The determine shows the vacuum clutch mechanism. This sort of clutch utilizes the existing vacuum within the motor manifold to operate the clutch. The vacuum clutch includes a reservoir, non-return valve, vacuum cylinder with piston, and solenoid valve.  Normally area the flat aspect in the clutch plate against the motor. https://claytonwkscl.bloggactif.com/34209538/5-tips-about-clutch-kereta-you-can-use-today