Oxidation is the main cause of deterioration of lubricating oil, and the lubricating oil is oxidized due to exposure to air during use. For mineral lubricating oils, oxidation can produce macromolecular incompetence, which usually increases the viscosity of lubricating oil. For some synthetic oils, such as polyalphaolefins, polyester synthetic oils, etc., high temperature will cause long-chain molecular cracking of base oils. It becomes a structure of small molecules, so in the initial stage of oxidation, the viscosity will decrease.

For the excavator, when the hydraulic oil temperature is 50-80 ° C, the viscosity, lubricity and wear resistance of the hydraulic oil are in the best state, and the working efficiency is the highest. When the temperature of the hydraulic oil exceeds 95 °C, the efficiency of the excavator decreases, the movement is inaccurate and slow, and the excavator cannot work when it is serious.

The air compressor of a cement plant uses a certain brand of coolant. In May 2015, the oil change process was carried out. Shortly after the oil change, the oil was cokeed. As shown in the figure, after a long shutdown, the start-up was difficult and could not be normal. run.

At this point, the fault can be eliminated by draining the shock absorber fluid to the standard oil level. There are two reasons for the oil level of the shock absorber box being too high. One is that the operator blindly refuels; the other is that the oil seal of the shaft end of the hydraulic pump is aging, so that the hydraulic oil leaks, and the latter should be replaced by a hydraulic pump to replace the oil seal.

For circulating lubrication systems with filtration devices (eg hydraulic systems, turbine units), the optimum sampling point is in the return line; if it is to be judged that the equipment is worn, it should be sampled before the filter return line filter; if the filter is to be evaluated The filtering effect requires sampling both the front of the filter and the back of the filter;