Cummins 3914459 Fan Pulley is a replacement belt pulley for the engine cooling fan, designed for Cummins 5.9L and ISB-series engines including 4B, 4B3.9, 6A3.4, and 6.7 ISB QSB. As the fan drive pulley, it transfers rotation from the engine’s accessory belt to the cooling fan to maintain proper airflow. This part is identified by the Cummins part number 3914459 and is intended for belt-driven cooling system configurations in these engines.
