1) Hydraulic oil viscosity
The principle for determining the viscosity of hydraulic oil is to keep the viscosity of hydraulic oil in the optimal range (16-36x10-6m m2/s) on the premise of considering the working temperature and efficiency of hydraulic circuit; Viscosity of short-term cold start corresponding to the lowest ambient temperature ≤ 1000X10-6m ㎡/s; The viscosity corresponding to the maximum allowable oil leakage temperature of 90 ℃ for a short time is ≥ 10X10-6m ㎡/s.
(2) Viscosity index (VI)
This index directly reflects the property that the viscosity of oil changes with temperature. The higher viscosity index of oil indicates that the viscosity of this oil changes less with temperature; On the contrary, it is larger. The reduction of viscosity index will narrow the range of ambient temperature to which the oil can adapt. If it is not necessary to use the oil, you should consult the oil manufacturer for relevant information, make appropriate adjustments to the range of use of the oil, and change the relevant set values of the equipment if necessary.
(3) Other comprehensive performance
Because the working pressure of the hydraulic system of modern large-scale hydraulic excavator is high (≥ 32MPa), and the maximum allowable working oil temperature of the hydraulic oil is also high (about 90 ℃), in order to ensure that the hydraulic system can work normally during the normal oil change cycle, it is required that the lubricating property, oxidation stability, wear resistance, rust prevention and corrosion resistance, anti emulsification, anti foaming property Shear stability and extreme pressure load have good quality.
