Decoupling engine speed from cooling power

Project Name Hydrostatic Fan Drives
Industry Construction machinery, agricultural machines
Technologies Mobile hydraulics, mobile electronics
4EE Levers Energy System Design, Efficient Components, Energy on Demand

Demand-based fan drives for low fuel consumption


Initial Situation

In order to comply with today’s emission standards, engine manufacturers are shifting torque into lower engine speed ranges. At the same time, the demands on cooling performance are increasing in order to operate the engine within the optimum temperature range while lowering fuel consumption and emissions.

The Rexroth 4EE Solution

Hydrostatic fan drives decouple cooling power from internal combustion engine speed. The motor control unit communicates the current cooling requirements to the CAN bus-capable control electronics of the hydrostatic fan drive. The hydrostatic fan drive consists of a continuously variable displacement pump with ED control, developed especially for this application, and a fixed displacement pump.

The result

Hydrostatic fan drives lower fuel consumption of mobile machines by up to 5 percent.


  • Demand-based cooling independent of engine speed
  • Direct exchange of information with the motor control unit
  • Flexible component layout
  • Option for reverse fan function and standstill

Industry know-how for custom-made solutions

Construction machinery, materials handling, agricultural and forestry machinery, or commercial and road vehicles: Our industry specialists are familiar with the specific needs of your industries. Together with you, they will find custom-made solutions for more energy efficiency and productivity – worldwide.