The axial piston (AP) pump/motor was invented in 1907 and was the foundational product for the oil hydraulics power and motion industries of today. Although the axial piston pump has proven its utility in oil hydraulics for more than 100 years, it was not until the invention of modern composite and ceramic materials and precision manufacturing technologies that the unique axial piston design could be used with plain water.

   
 

Special materials and precision tolerances are required for water lubricated machinery because the lubricating film thickness of water is roughly ten times thinner compared to oil. A major advantage of water is that it does not degrade or require changing compared to oil lubricants. The Danfoss I-save and ERI Pressure Exchanger are other examples of water lubricated equipment that are uniquely compatible with the axial piston pump.