Hydraulic pump is the power source of excavator hydraulic system. It is an energy conversion device that converts mechanical energy into hydraulic energy. In the hydraulic excavator, the hydraulic pump is also the component with the most failures. What are the common failures of the hydraulic pump?
Cause of failure:
Check the boom cylinder for internal leakage. The simplest method is to raise the boom to see if it has obvious free fall. If the drop is obvious, disassemble the oil cylinder for inspection. If the sealing ring is worn, replace it.
Check the control valve. First, clean the safety valve and check whether the valve core is worn. If worn, replace it.
If there is still no change after the installation of the safety valve, check the wear of the control valve core. The service limit of the clearance is generally 0.06mm, and it should be replaced if it is seriously worn.
Measure the pressure of the hydraulic pump. If the pressure is low, adjust it. If the pressure still cannot be adjusted, it indicates that the hydraulic pump is seriously worn.
Generally speaking, the main reasons why the boom cannot be lifted with load are: a. the hydraulic pump is seriously worn. Serious leakage in the pump during low-speed operation; During high-speed operation, the pump pressure increases slightly, but due to wear and internal leakage of the pump, the volumetric efficiency decreases significantly, and it is difficult to reach the rated pressure. The long-time operation of the hydraulic pump intensifies the wear and tear, and the oil temperature rises, resulting in the wear of the hydraulic components and the aging and damage of the seals, loss of sealing capacity, deterioration of the hydraulic oil, and finally the failure.
The selection of hydraulic components is unreasonable. The seal is also a non-standard part, with high manufacturing cost and inconvenient replacement of the seal. The small cylinder diameter of boom cylinder will inevitably make the system set pressure high. The design of hydraulic system is unreasonable. It can be seen from Figure 1 that the control valve and the full hydraulic steering gear are single pump in series. The hydraulic pump often works under full load or overload (high pressure) for a long time, and the system has hydraulic impact. The oil is not changed for a long time. The hydraulic oil is polluted, which intensifies the wear of the hydraulic pump, resulting in the cracking of the pump shell.
After many demonstrations, the advanced priority valve and load sensing full hydraulic steering gear are finally adopted. According to the Steering requirements, the new system can give priority to the distribution of flow to it. Regardless of the size of the load and the speed of the steering wheel, it can ensure sufficient oil supply, and the rest can be supplied to the working device circuit, thus eliminating the loss of success rate caused by excessive oil supply in the steering circuit, improving the system efficiency and reducing the working pressure of the hydraulic pump.
Optimize the design of boom cylinder and hydraulic pump to reduce the working pressure of the system. The requirements of lifting force and speed of boom cylinder are met through optimization calculation. Pay attention to the correct use and maintenance of the loader during use, add or replace the hydraulic oil regularly, maintain the cleanliness of the hydraulic oil, and strengthen daily inspection and maintenance.
