The overflow valve is prone to high-frequency noise, which is mainly caused by the unstable performance of the pilot valve, which is the noise generated by the high-frequency oscillation of the front chamber pressure of the pilot valve. The main reasons are:

1. Air is mixed into the oil to form a cavitation phenomenon in the front cavity of the pilot valve to cause high frequency noise. At this time, the air should be exhausted in time and the outside air should be prevented from re-entering.

2. The needle valve is excessively worn due to frequent opening during use, so that the tapered surface of the needle valve and the valve seat cannot be tightly combined, resulting in unstable pilot flow and pressure fluctuations, which may cause timely repair or replacement.

3. The pilot valve is unstable due to the fatigue deformation of the spring, which causes the pressure fluctuation to be large and causes noise. At this time, the spring should be replaced.

Hydraulic cylinder noise

1. The air in the oil is mixed with air or the air in the hydraulic cylinder is not completely exhausted, causing cavitation under high pressure and causing large noise. At this time, the air must be exhausted in time.

2. The cylinder head oil seal is too tight or the piston rod is bent. During the movement, noise will also be generated due to the sturdiness. At this time, the oil seal or alignment piston rod must be replaced in time.

Pipeline noise

Excessive dead bends or loose clips can generate vibration and noise. Therefore, the bending of the pipe should be avoided as much as possible, and the loose clips should be tightened in time.

Plunger pump or motor noise

1. Suction is one of the main causes of excessive noise of hydraulic pumps. When air is mixed into the oil, it is easy to form cavitation in its high pressure zone and propagate in the form of pressure waves, causing oil to oscillate, causing cavitation noise. The main reasons are:

1) The oil filter of the hydraulic pump, the oil inlet pipe is blocked or the viscosity of the oil is too high, which can cause the vacuum at the pump inlet to be too high, so that the air penetrates.

2) The oil seal of the hydraulic pump and the pilot pump shaft is damaged, or the inlet pipe is poorly sealed, causing air to enter.

3) The oil level of the fuel tank is too low, so that the hydraulic pump inlet pipe is directly sucked. When there is high noise in the operation of the hydraulic pump, the above parts should be inspected first, and the problem should be dealt with in time.

2. The internal components of the hydraulic pump are excessively worn, such as the wear and strain of the piston pump cylinder and the distribution plate, the plunger and the plunger hole, etc., causing serious leakage in the hydraulic pump. When the hydraulic pump outputs high pressure and small flow. Flow pulsation occurs when the oil is used, causing higher noise. At this time, the deflection angle of the pilot system variable mechanism can be appropriately increased to improve the influence of internal leakage on the pump output flow.

The servo valve spool of the hydraulic pump and the piston that controls the flow will also cause the piston to pulsate during the movement due to local wear and strain, causing fluctuations in the output flow and pressure of the hydraulic pump, resulting in large vibration and noise at the pump outlet. . At this point, the components that are severely worn or strained can be brushed and replaced or replaced.

3. The hydraulic pump distribution plate is also one of the important components that easily cause noise. In the use of the distribution plate due to surface wear or sludge deposition at the opening of the unloading groove, the unloading groove will be shortened to change the unloading position, resulting in a trapped oil phenomenon, which in turn causes higher noise.

In the normal repair process, the flat-repaired distribution plate will also have the effect of shortening the unloading groove. If it is not properly lengthened at this time, it will generate more noise.

During the assembly process, the large unloading groove of the distribution plate must be installed in the high pressure chamber of the pump, and its sharp angle direction must be opposite to the direction of rotation of the cylinder block, otherwise it will bring greater noise to the system.

The hydraulic system of the excavator is a complex system composed of multiple components. The maintenance and repair difficulty is much larger than that of the mechanical transmission. The construction unit generally lacks the monitoring and maintenance equipment of the hydraulic system, so the hydraulic transmission system failure of the excavator is correctly judged and eliminated.

It is an important guarantee for efficient and safe work of excavators.