The serious wear of the hydraulic pump of the excavator has a fatal impact on the excavator, so such problems must be solved in time for the excavator. When repairing the hydraulic pump of the excavator, find the cause of the failure from the following three points:
1. Check the boom cylinder for internal leakage
The easiest way to do this is to raise the boom and see if it has a noticeable free fall. If the drop is obvious, dismantle the oil cylinder for inspection. If the sealing ring is worn, it should be replaced.
2. Check the control valve
First clean the safety valve, 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 spool of the control valve.
3. Measure the pressure of the hydraulic pump
If the pressure is low, adjust it, and the pressure still cannot be adjusted up, indicating that the hydraulic pump is seriously worn.
1. Generally, the main reasons that the boom cannot be lifted with load are:
(1) The hydraulic pump of the excavator is seriously worn
When running at low speed, the internal leakage of the pump is serious; when running at high speed, the pressure of the pump increases slightly, but due to the wear and internal leakage of the pump, the volumetric efficiency drops significantly, and it is difficult to reach the rated pressure. The long-term operation of the hydraulic pump aggravates the wear and the oil temperature rises, which causes the wear of the hydraulic components and the aging and damage of the seals, the loss of the sealing ability, the deterioration of the hydraulic oil, and finally the failure occurs.
(2) Unreasonable selection of hydraulic components
The specifications of the boom cylinder are 70/40 non-standard series, and the seals are also non-standard parts, so the manufacturing cost is high and the replacement of the seals is inconvenient. The small cylinder diameter of the boom cylinder is bound to increase the set pressure of the system.
(3) The hydraulic system design is unreasonable
The control valve and the full 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), and the system has hydraulic shock. If the oil is not changed for a long time, the hydraulic oil is polluted, which aggravates the wear of the hydraulic pump, so that the casing of the hydraulic pump bursts (it was later found that such failure).
2. Improvements and Effects
(1) Improve the hydraulic system design
After many demonstrations, the advanced priority valve and load-sensing full-hydraulic steering gear are finally adopted. The new system can give priority to allocating flow to it according to the steering requirements. No matter the size of the load or the speed of the steering wheel, it can ensure sufficient fuel supply, and the remaining part can be fully supplied to the working device circuit, thus eliminating the power caused by excessive fuel supply to the steering circuit. loss, improve the system efficiency and reduce the working pressure of the hydraulic pump. Reduce the serious wear of the excavator hydraulic pump.
(2) Optimized design of boom cylinder and hydraulic pump shape
Reduce system working pressure. Through optimized calculation, the boom cylinder adopts standard series 80/4. The displacement of the hydraulic pump is increased from 10ML/R to 14ML/R, and the set pressure of the system is 14MPA, which meets the lifting force and speed requirements of the boom cylinder.
(3) Strengthen daily inspection and maintenance
In the process of use, attention should also be paid to the correct use and maintenance of the loader, regularly adding or replacing hydraulic oil, maintaining the cleanliness of the hydraulic oil, and strengthening daily inspection and maintenance. In this way, serious wear of the hydraulic pump of the excavator can be avoided.