The hydraulic pump is the power source of the excavator hydraulic system. It is an energy conversion device that converts mechanical energy into hydraulic energy. In hydraulic excavators, the hydraulic pump is also the component with the most failures. What are the common failures of the hydraulic pump? Hydraulic pump is easy to wear due to frequent repair of excavator. Today, we will talk about the causes of hydraulic pump wear.
Failure cause:
Check the internal leakage of the boom cylinder. The simplest way 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 seal ring is worn, replace it.
Check the control valve. First, clean the safety valve, check whether the valve core is worn, and replace it if worn.
If the safety valve is still unchanged after installation, check the wear of the control valve core. The clearance limit is generally 0.06mm, and replace it if the wear is serious.
Measure the pressure of the hydraulic pump. If the pressure is too low, adjust it. If the pressure still cannot be adjusted, the hydraulic pump is severely worn.
Generally speaking, the main reasons for boom failure to lift under load are: a The hydraulic pump is severely worn. Serious leakage in the pump at low speed; At high speed, the pump pressure is slightly increased, but due to wear and internal leakage of the pump, the volumetric efficiency is significantly reduced, and it is difficult to reach the rated pressure. Long time operation of hydraulic pump aggravates wear and oil temperature rise, which causes wear of hydraulic components, aging and damage of seals, loss of sealing ability, deterioration of hydraulic oil and finally failure.
The selection of hydraulic components is unreasonable. The seals are also non-standard, with high manufacturing cost and inconvenient seal replacement. The small cylinder diameter of the boom cylinder will inevitably make the system set pressure high. The design of the hydraulic system is unreasonable. It can be seen from Figure 1 that the control valve and the full hydraulic steering gear are in series with a single pump. 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 aggravates the wear of the hydraulic pump, causing the pump shell of the hydraulic pump to crack.
After many demonstrations, the advanced priority valve and load sensing hydraulic steering gear are finally adopted. The new system can give priority to the distribution of flow according to the steering requirements. Regardless of the load and the speed of the steering wheel, sufficient oil supply can be guaranteed. 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. In the process of use, pay attention to the correct use and maintenance of the loader, add or replace the hydraulic oil regularly, maintain the cleanliness of the hydraulic oil, and strengthen the daily inspection and maintenance.
