HT650™ ON/OFF PNEUMATIC FAN DRIVE A drop -in replacement for a viscous fan drive.  The HT-650, when fully engaged, delivers the torque required by high airflow capacity fans.  The clutch is air engaged with a manual lock-up available in the event of air-loss.  It is ideally suited to mid-range trucks and those with water pump mounted fans. Many of today's medium and heavy-duty diesel engine trucks feature high-airflow capacity fans for their cooling systems. In order for these large fans to provide their maximum cooling benefit, the fan drive must deliver a high amount of torque. Choose the HT650™ On/Off Pneumatic Fan Drive. The "On/Off" feature of the HT650 eliminates any needless engagement of your fan, which robs precious horsepower and fuel economy from your engine. The HT650 is "On" only when the engine requires cooling. When the HT650 is "Off", it's completely disengaged. 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. Reliable Performance. That's what you'll get from Horton. With proven, hard-working products that return your investment for years to come. Backed by service and support second to none. HT650 INSTALLATION AND PRODUCT INFORMATION Master Horton Fan Clucth Listing Fan Clutch Selection Criteria Form .pdf RELATED PRODUCTS Horton Windmaster Fans NGC Fans