(1) improper selection of oil products
The brand, quality and viscosity grade of the oil do not meet the requirements, or the hydraulic oil with different trademarks is mixed to form too low or too high viscosity index of the hydraulic oil. If the oil viscosity is too high, the power loss will be added and the oil temperature will rise; if the oil viscosity is too low, the leakage will be added and the oil temperature will rise.
Preventive measures: The selection of oil should be determined according to the trademark recommended by the manufacturer and the working environment and temperature factors of the machine. For some machines with special requirements, special hydraulic oil should be selected; when the maintenance of hydraulic components and systems is inconvenient, anti-wear hydraulic oil with good performance should be selected.
(2) Serious pollution
Construction site environment is bad, with the addition of machine working time, impurities and dirt are easily mixed in oil. Contaminated hydraulic oil into the cooperation gap of pump, motor and valve will scratch and destroy the accuracy and roughness of the cooperation appearance, so as to increase leakage and oil temperature.
Preventive measures: Generally change oil after more than 1000 hours of cumulative work. When changing oil, pay attention to not only discharging the old oil in the tank, but also replacing the old oil in the pipeline and working circuit of the whole system. When refueling, it is better to use more than 120 mesh filter, and add enough oil according to the rules, so that the oil has sufficient circulating cooling conditions. In case of sudden malfunction caused by hydraulic oil pollution, it is necessary to filter or replace the oil used in hydraulic system. For example, a Yzt14g roller presents the problems of high temperature of hydraulic oil and lack of vibration force; the inspection shows that the hydraulic oil is milky white, has been transformed, the viscosity has decreased, and the operation of the roller has returned to normal after replacing the hydraulic oil.
(3) Low oil level in hydraulic tank
If the amount of oil in the hydraulic tank is too small, the hydraulic system will not have enough flow to take away the heat generated, resulting in an increase in oil temperature.
In the actual operation and maintenance process, strictly abide by the rules of hydraulic oil level in the operating rules. For example, a PC2003 hydraulic excavator, after working for a period of time, presents the problem that the temperature of hydraulic oil is too high; looking at the hydraulic oil tank, it is found that the oil level is much lower than the regular value. Due to the excessive lack of oil in the hydraulic system, the hydraulic oil circulation is too fast and the heat dissipation is not enough, resulting in an increase in the oil temperature; after adding enough hydraulic oil according to the rules, the temperature of hydraulic oil immediately drops to the normal scale.
(4) Mixing air into hydraulic system
Air mixed in hydraulic oil will escape from oil and form bubbles in low pressure area. When it moves to high pressure area, these bubbles will be smashed by high pressure oil, which will be compressed sharply and emit a lot of heat, causing oil temperature to rise.
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