Self-Adjusting Clutch (SAC)
When the facing on a clutch driven plate wears, the normal working position (travel) of the pressure plate and the disengagement position increase.
On the self-adjusting clutch an adjuster ring responds to the wear of the clutch driven plate. As wear increases, the adjustment ring moves automatically slightly at the next disengagement and adjusts the bearing position of the diaphragm spring. This means that the operating travel of the pressure plate and therefore engagement pressure remain constant.