Basically, most failures of excavator hydraulic system are caused by hydraulic oil. If the hydraulic oil is not replaced for a long time, there will be blackening and viscosity reduction. It directly leads to abnormal wear of hydraulic system parts such as injection valve, multi-way directional valve and oil seal in the main pump of excavator. After a long time, the clearance between parts is too large and internal leakage occurs, which seriously affects the consistency and weakness of excavator action. This article will summarize some phenomena and causes of deterioration of hydraulic oil for reference only.
1. The hydraulic oil is too dirty and black
1) Internal cause: metal impurities such as iron filings are the main factors affecting the blackening of excavator hydraulic oil. Due to the high-speed rotation of the hydraulic pump, the repeated operation of the hydraulic valve spool and the repeated operation of the oil cylinder will produce iron filings, which will not be cleaned for a long time, thus affecting the quality of the hydraulic oil. In addition, if it is a newly purchased excavator, a large amount of metal impurities will be generated during running in. When replacing the hydraulic oil, empty all the hydraulic oil in the oil tank, wipe the oil tank with cotton cloth, and then add new hydraulic oil. If it is not emptied, there may be a large amount of iron filings left in the oil tank, which will also cause the new hydraulic oil to be polluted and blackened.
2) External reasons: the main reason is that the working environment of the excavator is relatively poor, and external pollutants enter the hydraulic oil. The working environment of the excavator is too poor, resulting in the blockage of the filter element. The dust-proof measures are not in place in the process of cleaning, replacing hydraulic oil and maintenance. Impurities are brought into the hydraulic system during operation. Therefore, it is necessary to often check whether the hydraulic system of the excavator is closed and whether the breathing hole is intact. Check whether the seals of the exposed parts of the hydraulic part of the excavator are intact, such as the dust ring of the oil cylinder.
2. The hydraulic oil is white and turbid
If the hydraulic oil appears white turbidity, the cause of solid impurities or liquid viscous impurities can be eliminated, which can only be caused by water or air. The most reliable way is to sample the hydraulic oil and send it to the testing organization for testing. The oil sample can also be dropped on the hot iron plate. If bubbles appear, that is, the water turns into water vapor at high temperature to form bubbles, so it can be determined that there is water in the hydraulic oil. If the hydraulic oil is mixed with water to cause turbidity, let the hydraulic oil stand for a period of time, make the water sink to the bottom of the hydraulic oil tank, and then remove the water. However, if the hydraulic oil is emulsified due to high moisture content, it needs to be replaced with a new hydraulic oil. If it is determined that the turbidity is caused by air mixed in the hydraulic oil, check whether the hydraulic system pipeline leaks and cut off the air mixing source.
