Abstract: A unidirectional transmission for an alternator assembly includes a two way bearing and a separately-housed unidirectional bearing. The two-way bearing is coupled between a pulley and a rotor shaft, and is operable to provide substantially neutral rotational coupling between the pulley and the rotor shaft. The separately-housed unidirectional bearing is also coupled between the pulley and rotor shaft, the unidirectional bearing operable to provide substantially positive rotational coupling between the pulley and rotor shaft when the pulley increases its rotational speed in a predefined rotational direction, and further operable to provide substantially neutral rotational coupling between the pulley and rotor shaft when the pulley decreases its rotational speed in the predefined rotational direction.