Abstract: Invention relates to an on-board electrical generator system that may be retrofitted to existing railroad vehicles, such as freight cars, box cars, and the like, where rotation of the vehicle's axle powers the system. A preferred use thereof is to charge the battery for the electrically controlled brakes on the vehicle. Such vehicles typically include a chassis, having plural axles mounted thereon, and a journal box or adaptor block having a projection generally aligned parallel with the axles. Each axle contains a pair of wheels, which are inwardly mounted from the respective axle ends and rotatable with the axle. The generator includes a rotor fixed for rotative movement relative to a stationary stator, whereby such relative movement causes electric currents to be generated in the stator containing the generator in a non-rotatable housing.