Spurred by new demands for efficiency, hydraulic equipment across the industrial and mobile markets is rapidly evolving. For hydraulic fluids and lubricants, this kind of evolution represents both a challenge and opportunity. Not only must these fluids be able to deliver robust protection under increasingly strenuous operating conditions, but they also can directly improve operational efficiency.

Among the current market trends and their implications for hydraulic fluids:

Increasing power density and internal pressures. Modern hydraulic system design increasingly prioritizes lightweighting and power density in order to best compete with electric systems that continue to gain marketplace traction. These design parameters result in much higher internal operating pressures, which can be as high as 450 bar in current mobile equipment. Pressure levels are likely to only grow higher.

However, higher pressure increases the potential for internal fluid leakage. This phenomenon can lead to a reduction in the clearances between moving parts, which can severely compromise machine durability. As such, lubrication here has needed to move from hydrodynamic protection into the mixed film region, requiring new additive technologies and formulation expertise.

Finer filtration. Higher pressures and lower clearances in hydraulic components also mean that fluids must remain very clean throughout components’ operating life. Wet filterability has become a critical fluid performance parameter for fluids because even tiny particles that may become trapped between moving parts can have serious consequences.

Smaller oil coolers and reservoirs. In order to save space and further reduce weight, the size of new oil coolers and reservoirs are smaller. The challenges here for hydraulic fluids are significant—in smaller applications, operating temperatures can increase by as much as 10°C, effectively halving the fluids’ life. Smaller cooler and reservoir sizes also mean that less fluid is doing the same amount of work, which may increase the severity of operating conditions. Such fluids must be formulated to demonstrate thermal stability, and increased additive levels will be required to maximize performance.

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