During the normal construction of excavator, if the hydraulic oil temperature rises too fast and the temperature is too high, the internal leakage of the hydraulic system will be increased on the one hand, and the operation speed will be significantly reduced, thus damaging the hydraulic precision parts.
Failure cause analysis:
Case 1:
① There are unreasonable places in the design of the hydraulic system. Although the probability of this reason is relatively small, it cannot be ruled out. For example, some hydraulic pipelines have too small pipe diameters, some pipe joints have poor oil flow to produce throttling, and some pipe bending radii are too small.
② The opening of the valve hole is too small. If the reason is determined, the valve with a large opening must be used according to the demand.
③ If the opening pressure of safety valve, speed limiting valve and pressure reducing valve is too high, the opening pressure of the above valves shall be readjusted according to the specified value.
The second case:
Check whether the cooling fan operates normally. If the fan speed is abnormal, the independent cooling system may be caused by the following three reasons:
① The fan motor is severely worn, which is a common cause. Once the fan motor is severely worn, the internal leakage must be large, and the fan motor should be replaced.
② The gear oil pump supplying pressure oil to the fan motor is seriously worn, resulting in large internal leakage; The gear pump should be replaced.
③ If the fan motor speed is normal and the hydraulic oil temperature rise is still very high, check whether there is too much dirt on the cooler surface, which will affect the cooling effect. If so, remove the dirt. If the surface of the cooler is clean, adjust the distance between the fan blade and the cooler to ensure the cooling effect.
④ For excavators that are not independent cooling systems, the owner should also check whether the fan belt slips. If the fan belt slips, adjust the tension of the fan belt or replace it with a new one.
The third case:
After troubleshooting the cooling system, if the hydraulic oil temperature is still very high, the maintenance personnel should carefully check whether there is abnormal noise in the hydraulic system. If there is noise, measures should be taken against the noise source to eliminate the fault.
The fourth case:
If the main safety valve or the secondary overload valve is opened too frequently, the hydraulic oil temperature will rise too fast and too high. The frequent opening of main safety valve or secondary overload valve can be overcome by correct operation according to the following methods:
① Single action should not be too much, and multiple actions should be done as much as possible during excavation.
② When excavating, try not to touch or touch the stopper, and reduce or avoid the opening of the relief valve of the main safety valve or the secondary overload valve.
The fifth case:
Using unqualified hydraulic oil will also cause the oil temperature to be too high. You can check whether the hydraulic oil in the machine has the following conditions. If so, you must replace the oil in time
① Hydraulic oil contains water or impurities;
② Hydraulic oil viscosity is too high;
③ The viscosity of hydraulic oil is too small.
