Please read the entire description...A look at the heart of an AWD system! Apologies for using both terms “pilot” and “control”, for the purposes of this video they are interchangeable. Relative rotation of the control (pilot) cam acting on the main through the balls provides main clutch pack clamping. Rotation is initiated when the coil is energized producing a magnetic field drawing in the armature, clamping the control (pilot) disks...Greater the magnetic field strength (a function to the duty cycle of the control signal applied) the greater the pull on the armature. Translating into more or less drive coupling as a function of clutch pack compression force.