VMaster Directly Controlled Viscous Fan Clutch

Product Type: Fan Clutches
VMaster Directly Controlled Viscous

Based on pulse-width-modulation (PWM) signals from the engine management system, VMaster viscous directly controlled fan clutch (fan drive) adjusts its output to provide just the degree of cooling needed.


  • Heavy-duty trucks
  • Medium-duty trucks
  • Light-duty trucks
  • Automotive
  • Variety of off-highway equipment

Features & Benefits

  • Pulse-width modulation (PWM) signals from engine management system provide fast response to changing cooling requirements enhancing fuel economy, reduced noise and maximum efficiency
  • Compatible with many engine management systems for design flexibility
  • Modular design allows use with Horton and other fan manufacturer products
  • Improved outer tube design and simplified mounting system provides easier installation

After the first electromagnetically controlled viscous fan cluches were introduced to European standard series production by Sachs in 1999, the company has been putting its expertise into developing a convincing new product. Based on a PWM signal (pulse-width-modulation) from the engine management, the directly controlled fan clutch adjusts its speed to meet the engine cooling requirements. The integrated speed monitoring system ensures a constant fan speed that is largely independent of the engine speed.

Directly Controlled Viscous Charts

Directly Controlled Viscous Charts

Features And Benefits

  • Rapid responsiveness – Fan speed is adjusted with almost no delay to changing cooling requirements. Engagement from idle state takes place within 10 seconds. Disengagement takes place within 10 to 30 seconds, depending on the input speed (see functional diagrams).
  • Low idling speed – Standard idling speed is approximately 250 rpm. Lower idling speeds are less suitable because the fan obstructs the air flow through the radiator which results in increased fuel consumption. Higher speeds can be individually selected by the customer.
  • Greater torque transmission – Torque transmission is considerably improved for today’s unit sizes, which means that for a given unit size, a greater torque can be transmitted; or for a given torque, the unit size can be smaller.
  • Improved bearing arrangement – The components have been streamlined and reduced in weight, allowing different types of bearings to be used.
  • Better heat removal – The outer tube arrangement enables a substantially better heat removal and a longer operating life.
  • Simplified mounting – The magnet unit is integrated in the fan clutch on the engine side, which enables a simple electrical connection to the engine management system. Assembly costs are thus considerably lower than they would be for mounting the unit on the radiator side.
  • Variable fan use – The fan clutch can be used with fans from Horton Sachs and other manufacturers.
  • Advantageous cost/benefit ratio – The features of the design combined with our production technology allow for a competitive price.
  • Modular solution – We have designed our fan on a modular basis (fan clutch plus fan). Accordingly Horton Sachs fan modules comply with individual customer requirements.
  • Endurance test – The fan clutches were approved for 500 hours on an engine for heavy-duty trucks.
  • Customer samples – Test our fan clutch. We will provide you with a sample according to your specifications.