Sensitivity analysis of operating parameters in hydraulic systems with respect to the aging of hydraulic fluids

In this work, a novel oil aging test-rig based on a real hydraulic system is introduced. This device allows an accelerated fluid-aging rate under high hydraulic loads. Furthermore, it is possible to vary the operating parameters to evaluate the different factors that influence the aging behavior of hydraulic fluids. Oil samples, which are aged under different conditions, are analyzed using FTIR to estimate the rate of aging using the degradation process of Zinc dialkyl dithiophosphate (ZDDP). The results show a clear aging behavior dependent on different operating parameters in hydraulics. In addition to the degradation of ZDDP, the depletion of the phenolic antioxidant (AO) and the formation of a varnish film on metallic surfaces can be observed.