The disclosure is directed to preserving data consistency in a multiple-node data storage system. The two output shafts drive respective tracks of the vehicle, and are driven by the propeller shaft via the interposition of respective identical reduction units. Thus, the stripping roller exhibits peelability required for stripping of the image forming material from the image recording medium and releasability required for removal of a transferred image forming material from the stripping roller. A control circuit varies the amount of torque of the electric motorgenerator unit rotary shaft between a negative and a positive value as a function of the operating condition of the vehicle.