Clean air fans with hinged hoods exhaust stale air and supply fresh air for the general ventilation of a structure. They feature a drum reversing switch to allow them to function as both supply and exhaust fans. Their hinged hoods swing open and expose the ventilator fan components for cleaning, maintenance, or service. Belt-drive fans are typically quieter and provide more control over the fans' blade speed and airflow than direct-drive fans. These fans come with a drive package that includes a motor, sheaves, belts, drum switch, and bushings.