The PTO clutch assembly is readily connected to a shaft. One method includes operations for receiving requests to be processed, and for associating each request to one task. The light source device comprises a high intensity discharge lamp, a reflector having an opening and surrounding the high intensity discharge lamp, and a cover covering the opening. Further, the cooling apparatuses are arranged in an upper side of the driving system apparatus, and a cooling fan is installed in an upper side thereof. This property benefits electrochemical power source applications such as batteries and capacitors.