Developing the HydraulicIDEAL Fluid

ID POW U E L R Fluid Power Journal Official Publication of the International Fluid Power Society Change Service Requested F INTERNATIONA L For Fluid Power & Motion Control Professionals in Hydraulic, Pneumatic, Vacuum & Electric Control Technologies S O C I E T Y Developing the Ideal Hydraulic Fluid By Eaton Hydraulics Division

It started out as one of those questions that are frequently posed when a group of colleagues get together: “What would you include in the design of the ideal hydraulic fluid?” The question was posed by a fluid supplier and might have been dismissed as small talk, except that it was directed to Thelma Marougy, one of a very small group of people with the knowledge and experience to answer it authoritatively. helma is recog- “Unless the customer is meeting some spe- “Once the base was selected and the additive nized and respected cific requirement, like using a food-grade oil in a package designed, the prototype fluid was rigor- throughout the in- food processing plant, the best choice is almost ously tested,” Marougy noted, “and fluid testing dustry,” said Doug always a petroleum base stock combined with is something we know a lot about.” Jahnke, product an engineered package of additives,” Marougy The candidate fluid was subjected to extreme “Tmarketing manager. “When she speaks, ev- said. “But, not all base stocks are equal and all bench testing that far exceeded industry stan- eryone listens because nobody knows more additive packages certainly are not equal. What dards, plus a special severe extended Vickers® about hydraulic fluids than Thelma. After we find is that most fluid suppliers sell two 35VQ25 pump test to demonstrate its ability to more than 20 years, she’s seen it all, and more grades of fluid – one is low grade and the other withstand long-term use in the most demand- important, she knows what to do about the is a little better. A few also sell what they call a ing application environments. While currently problems she finds.” Marougy is based at the ‘premium fluid’ that is a little better than their available “premium” fluids typically begin to company’s R&D center in Southfield, Mich. ‘little better’ product.” fail at 800 hours, the new formula was tested Intrigued by the question, Marougy set She added, “Hydraulic components have to 1,400 hours before any signs of degradation about developing a set of specifications for certain very consistent appetites when it were noted. an “ideal” hydraulic fluid based on her ex- comes to fluids. Once you understand that, These tests conformed to the company’s perience. But to her this was no academic the challenge is to select the appropriate standard ATS-373 protocol and the industry exercise, and when she brought the concept base stocks and then design the proper addi- standard ASTM D-6973 series. The candidate to Jahnke, he immediately recognized the tive package to achieve the desired results. In fluid was also tested extensively for compatibil- commercial value of what she had done. this project, we worked with the leading ad- ity with various hose compounds and with pro- The concept behind the commercialization of ditive manufacturer to develop tocols other than the Vickers 35VQ25 pump test. the project was simple: develop the package and partnered with Among these were tests for leakage and swell- a premium hydraulic Valvoline to provide the blend- ing, as well as hydraulic impulse testing. Both fluid that would extend Figure 1 ing capabilities and help with premium and standard hoses were included the life of the compa- product distribution through in the testing. ny’s pumps, motors and their network.” “We were designing a premium fluid,” Jahnke valves to deliver even Figure 2 said, “and that meant it had to meet perfor- greater value to custom- mance requirements for all system com- ers who depend on them. ponents, not just pump and motor While there were a few wear. It’s unusual to test compat- “premium” fluids on the ibility with hose compounds when market, none of them was developing a hydraulic fluid, but (it) is developed by a company an unusually good product.” that also produces hydrau- “We settled on three standard vis- lic components. cosities,” Marougy noted, “AW 32, AW 46 According to Marougy, and AW 68. These meet the needs of the Eaton is uniquely positioned broadest selection of our customers while to undertake this project offering choices for those with special re- because the company quirements. The heavy AW 68 fluid is often manufactures a full range The additive package includes chosen for sensitive applications where its of pump and motor technologies. “Piston more zinc dithio-phosphates (Super ZDDP) than increased viscosity reduces leakage; howev- pumps and motors are different from vane conventional hydraulic fluids, plus other pro- er, it would be at the price of a small reduction pumps and motors, and are different from prietary additives. According to Marougy, low- in overall system efficiency. The other two, AW gerotor pumps and motors and geroller quality ZDDP will form corrosive and insoluble 32 and AW 46, meet nearly all stationary system pumps and motors,” she said. “They all by-products that can plug filters, stick valves, requirements. AW46 and 68 meet most mobile have their idiosyncrasies and they all have and attack and corrode yellow metals such as application requirements.” their operating niches. We were tasked with bronze and brass. “This premium formulation designing a premium fluid that performed effectively eliminates those problems and deliv- Figure Identification: equally well in all of them, as well as in valves ers outstanding performance.” 1. Thelma Marougy and other hydraulic system components. It The fluid uses a standard base stock rather 2. Eaton 35VQ25 pump certainly was not a simple challenge, but it than an expensive synthetic base because was one I was confident we could achieve.” a standard base provides all of the perfor- For more information, contact Eaton Virtually any liquid can be used in a hydrau- mance required in nearly all industrial appli- Hydraulic Operations at www.eaton.com/hy- lic system, including water, motor oil, tractor oil, cations – as long as it is blended with the right draulics.com. vegetable oils, food-grade oils, non-staining oils additive package. According to the company, and a variety of specialized products. But the the product will improve the efficiency and mere fact that a specific liquid can be used does maximize the service life of the equipment not make it a good choice. it’s used in.

www.ifps.org | www.fluidpowerjournal.com Reprinted from September/October 2008 |