Auxiliary Drive unit drive the vehicle accesories such as radiator fans, vehicle compressors, generators and etc. It is posible to offer speed up/down output and the putput of orthogonal direction. Also the drive power can be disconnected freely by the conbination with wet multiple clutch or hydraulic coupling. One of Auxiliary Drive units, CSU"Constant Speed unit" consist with slipping clutch and electrinic control system. By these component, the pressing force of the clutch plate is automatically adjusted according to the fluctuation of the engine speed. By this fanction, the generator rotation speed (frequency) is always kept constant contrary to engine speed fluctuations and generator load fluctuations during vehicle running.