Examining Fluid Efficiency and Contamination Control Effects in Hydraulic Motors


Crane winch


Fluid power directly impacts machine reliability, productivity, and energy consumption. “For working machines, reliability, productivity, and energy consumption not only affect the total cost of ownership, but they also flow right to the bottom line.”

There has been continual research and upgrades in the quality and life of oils, lubricants, and hydraulic fluids, notes Paul Michael, Manager of Tribology Research at the Milwaukee School of Engineering (MSOE) Fluid Power Institute. “The Holy Grail, if you will, for oils, lubricants, and hydraulic fluids is to be able to use them forever without having to change them. Organizations are continuously researching different ways to improve the performance of oils, lubricants, and hydraulic fluids so they can be used longer and require less maintenance.”

Contamination control and filtration

Having a solid understanding of contamination control and filtration is essential for getting the maximum life out of oils, lubricants, and hydraulic fluids and this benefits the entire system over time, says Michael.

“The limiting factor in fluid life oftentimes is the contamination that can occur to the fluid. If a fluid becomes contaminated, either with water, dirt, or wear debris, it may be necessary to change the fluid and refresh the system with new fluid.

“Contamination is one of the potential drivers for the end of life for a hydraulic fluid,” points out Michael. “In a hydraulic system, the fluid transmits the power. In order for the power transmission to take place, the fluid must be maintained within what is called a pressure envelope – the pumps, hoses, valves, cylinders, etc., that are actually transmitting power and doing the work of the machine. To keep the fluid contained in the pressure envelope, it is necessary to have very tight gap control in the moving components within the hydraulic system.”

By way of example, the gaps between the cylinder, pistons, and cylinder bore in a pump, or between the spool and the manifold in a valve, must be maintained very tightly, otherwise, there is gap flow that occurs, he says. Gap flows are undesirable because they diminish productivity and generate heat. To maintain these critical gaps in the moving areas of the hydraulic system, the fluid must be very clean.

“In most other lubricating systems, the lubricant is not transmitting the power and is not encapsulated within a pressure envelope,” he points out. “The cleanliness requirements for gear oils, engine oils, automatic transmission fluids, and compressor oils are relatively lenient because these applications operate at lower pressures and control of gap flow is less.”

Michael says there are several ways to determine when it is time to change oil. Commonly, the change interval is based on time, miles, season, or condition-based monitoring.

For more insights that will give your business a competitive advantage, Michael will be presenting an education session – Hydraulic Fluid Properties, Efficiency and Contamination Control – at the 2023 International Fluid Power Exposition (IFPE) being held in Las Vegas, NV, March 14-18, 2023.

Attendees of the session will learn how to:

  • Figure out the sources, symptoms, effects, and best practices to avoid various types of contamination.
  • Recognize the different types of hydraulic fluids, their properties, and their standard test methods.
  • Perform hydraulic fluid sampling and analysis and how to interpret the analysis report.
  • Understand filter performance ratings.

“All the information will be presented in a combination of case studies and traditional training strategy,” notes Michael.


Co-located within CONEXPO-CON/AGG, IFPE provides an unmatched opportunity to harness the power of in-person connection. Engineers can meet with potential partners to discuss processes for streamlining the integration of sensors with hydraulic systems, all with the latest innovations in fluid power at their fingertips.

Learn more about the show and the endless possibilities that come with collaboration on the front lines of fluid power. Take advantage of discounted rates available and register for IFPE 2023 today

About the speaker

Paul Michael MSOE headshotMichael has 40 years of experience formulating and testing lubricants. He joined the MSOE Fluid Power Institute 17 years ago. Based in Milwaukee, WI, the Fluid Power Institute has become a leader in motion control and fluid power education, research, and evaluation. Michael’s area of expertise, tribology, is the science and technology of interacting surfaces in relative motion.

He is active in ASTM International – one of the world’s largest international standards-developing organizations, ISO (International Organization for Standardization) and National Fire Protection Association (NFPA) standards committees.

A lubrication subject matter expert for the U.S. Military, he has more than 50 publications on the topics of energy-efficient fluids, hydraulic fluid compatibility, filtration, particle characterization, and machinery lubrication.

IFPE’s comprehensive education program is the leading source for executives, engineers, manufacturing plant and operation leads, technicians, mechanics, and other fluid power professionals covering the latest technical topics and trends. Click here for more information.


Mark your calendar for IFPE, March 14-18, 2023, at the Las Vegas Convention Center, and take advantage of discounted rates available and register for IFPE 2023 today


Read Next

Improving Efficiency In Pneumatic Systems

Understanding the Fundamentals of Hydraulic Systems 

Get Ahead Of The Top 3 Trends Impacting The Fluid Power Industry In 2022