Maximum Efficiency Hydraulic Fluid, or MEHF, is a new hydraulic fluid from RohMax, Horsham, Pa., that produces significant improvements in hydraulic pump efficiency.

All over the world, power density in mobile hydraulic equipment has increased, meaning newer machines exhibit greater power output from a smaller envelope. With this increase in stress, operating temperatures have also increased. Historically, hydraulic fluid temperatures in mobile equipment ran between 75° and 80°C; now 100°C operating temperatures are not uncommon.

High-viscosity index improvers in MEHF products offer greater resistance to changes in viscosity with temperature than traditional hydraulic fluids do. This translates into lower viscosities at start-up and higher viscosities at operating temperature, which, in turn, translates into higher pump efficiency.

With fluid at the right viscosity, the pump will operate in a range of optimum efficiency. Too high a viscosity produces excessive torque drag on the pump, resulting in low mechanical efficiency. However, too low a viscosity allows excessive fluid to flow past the moving parts of the pump (internal leakage), resulting in low volumetric efficiency. With MEHF, the pump operates at the right viscosity levels, reducing overheating and improving equipment uptime.

By keeping viscosity within a narrow range, regardless of temperature, MEHF minimizes mechanical energy losses at low temperature and reduces internal pump leakage at high pressures and temperatures. The resulting improvement provides many advantages, including less need for heat exchangers and faster motion for improved productivity.

The primary advantage of MEHF is significant energy savings per unit of work, which can improve fuel economy of the engine driving the hydraulic system. For equipment manufacturers, MEHF improves pump efficiency, meaning-smaller pumps may be able to supply equivalent power compared with larger pumps using standard fluid.

For more information, contact Charles Dustman of RohMax at ( 215) 706- 5804, or visit