Severe wear of the excavator hydraulic pump has a fatal impact on the excavator, so such problems must be solved in time. When repairing the excavator hydraulic pump, look for the cause of the fault from the following three points:
1. Check the internal leakage of the boom cylinder
The simplest method is to raise the boom and see if it has obvious free fall. If the drop is obvious, disassemble the cylinder for inspection. If the sealing ring is worn, replace it.
2. Check control valve
First clean the safety valve and check whether the valve core is worn. If worn, it should be replaced. If there is still no change after the safety valve is installed, check the wear of the control valve core. The clearance limit is generally 0.06MM. If the wear is serious, it should be replaced.
3. Measuring hydraulic pump pressure
If the pressure is low, adjust it. If the pressure still cannot be adjusted up, it means that the hydraulic pump is seriously worn.
1. Generally, the main reasons why the boom cannot be lifted with load are:
(1) The excavator hydraulic pump is severely worn
When running at low speed, the leakage inside the pump is serious; when running at high speed, the pump pressure increases slightly, but due to the wear and internal leakage of the pump, the volumetric efficiency drops significantly, making it difficult to reach the rated pressure. Long-term working of the hydraulic pump aggravates the wear and oil temperature, which causes the wear of the hydraulic components and the aging and damage of the seals, loss of sealing ability, deterioration of the hydraulic oil, and finally leads to failure.
(2) Unreasonable selection of hydraulic components
The specification of the boom cylinder is 70/40 non-standard series, and the seals are also non-standard parts. The manufacturing cost is high and the replacement of the seals is inconvenient. The small diameter of the boom cylinder will inevitably make the system setting pressure high.
(3) Unreasonable design of hydraulic system
The control valve and the fully hydraulic steering gear are connected in series with a single pump. The set pressure of the safety valve is 16MPA, and the rated working pressure of the hydraulic pump is also 16MPA. The hydraulic pump often works under full load or long-term overload (high pressure) conditions, and the system has hydraulic shock. If the oil is not changed for a long time, the hydraulic oil will be contaminated, which will aggravate the wear of the hydraulic pump and cause the hydraulic pump casing to burst (it was later discovered that such failure).
2. Improvements and effects
(1) Improve hydraulic system design
After many demonstrations, the advanced priority valve and load-sensing full hydraulic steering gear were finally adopted. The new system can prioritize the distribution of flow to it according to the steering requirements. It can ensure sufficient oil supply regardless of load size and steering wheel speed. The remaining part can be fully supplied to the working device circuit, thus eliminating the power loss caused by excessive oil supply to the steering circuit. loss, improves system efficiency and reduces the working pressure of the hydraulic pump. Reduce serious wear and tear on the excavator hydraulic pump.
(2) Optimize the design of boom cylinder and hydraulic pump shape
Reduce system working pressure. Through optimization calculations, the boom cylinder adopts the standard series 80/4. The hydraulic pump displacement was increased from 10ML/R to 14ML/R, and the system pressure was set to 14MPA, which met the lifting force and speed requirements of the boom cylinder.
(3) Strengthen daily inspection and maintenance
During use, you should also pay attention to the correct use and maintenance of the loader, regularly add or replace hydraulic oil, maintain the cleanliness of the hydraulic oil, and strengthen daily inspection and maintenance. This will prevent serious wear and tear on the excavator hydraulic pump.
