Open circuit pump w/ piston motor

Efficient performance

Danfoss continues to lead the industry with groundbreaking fan drive technologies like our reverse displacement motor (RDM). By occasionally changing the airflow direction, accumulations of debris can be dislodged from the vehicle’s radiator to help ensure efficient cooling system performance.

When used in radiator cooling fan applications, the Danfoss RDM uniquely incorporates the external shift valve within the motor itself, eliminating the directional control valve, and either simplifying or completely eliminating the HIC block. With fewer components in the hydraulic circuit, the RDM frees up space in the engine compartment to create additional opportunities for innovation.

Design advantages like this help combat the challenges brought on by today’s harder-working, hotter-running Tier 4-compliant engines, where emission control equipment takes up more under-hood space than ever before. Building on our proven efficiency and reliability, the compact Danfoss RDM motor is technology that’s helping Danfoss engineer tomorrow.

Danfoss offers a wide range of efficient fan drive systems. Below are the benefits and critical considerations you need to take into account as you determine the right system for your specific needs.

Improvements in reversing fan drives

Improvements in reversing fan drives presentation


Increased efficiency due to variable flow and piston motor technology

Fan speed independent of engine speed

Fails to full fan speed

Motor speed sensors available

Higher motor pressure, power and life ratings

Less engine power consumption

Critical considerations

Back pressure required for axial piston motors

No ZERO speed capability

Larger reservoir capacity required for high flows

Motor thrust load capability must be calculated