This clutch transmits torque from the gearbox output to the input shaft of the gathering chain drive in the corn header. It engages and disengages the drive to the snapping rolls and gathering chains, allowing the operator to stop the header mechanism independently of the combine’s main driveline. A worn or slipping clutch causes inconsistent chain speed, leading to uneven crop intake and potential plugging of the header. The original unit is machined to the same engagement pressure and friction-face geometry as the factory assembly, so no shimming or spring-rate adjustment is needed during replacement.