The HT650 On/Off Pneumatic Fan Drive engages only when cooling is needed, resulting in reduced horsepower and fuel consumption. In the off mode, the HT650 completely disengages.  The HT650 is engine controlled, providing the best possible response time.

When engaged, the HT650 can deliver the maximum torque required by high-airflow capacity fans, without slipping. Whether you're hauling a heavy load up a long grade in summer heat, or need heat to your cab in cold weather, the on/off fan control of the HT650 will perform under the most severe conditions.