Excavator hydraulic pump serious wear reasons and improvement methods

Severe wear of the Hydraulic Pump of an excavator has a fatal impact on the excavator, so such problems must be solved in time. When repairing the hydraulic pump of an excavator, find 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 to see if it has obvious free fall. If it falls obviously, disassemble the cylinder for inspection. If the seal ring is worn, it should be replaced.

(2) Check the control valve
First, clean the safety valve and check whether the valve core is worn. If it is 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 it is severely worn, it should be replaced.

(3) Measure the pressure of the hydraulic pump
If the pressure is low, adjust it. If the pressure cannot be adjusted, it means that the hydraulic pump is seriously worn.

1. The main reasons for the failure of the boom to lift with load are:

1. Severe wear of the excavator hydraulic pump
The pump leaks seriously when running at low speed; when running at high speed, the pump pressure increases slightly, but due to the wear and leakage of the pump, the volumetric efficiency decreases 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 sealing ability, the deterioration of the hydraulic oil, and finally the failure.

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, with high manufacturing costs and inconvenient replacement of seals. The small bore of the boom cylinder will inevitably make the system set pressure high.

3. Unreasonable design of the hydraulic system
The control valve and the full hydraulic steering gear are connected in series with a single pump, the safety valve is set to 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 impact. 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 housing to burst (such faults were found later).

2. Improvement and Effects

(1) Improvement of Hydraulic System Design
After many demonstrations, the advanced priority valve and load sensing full hydraulic steering gear were finally adopted. The new system can allocate flow to it according to the steering requirements. Regardless of the load size and steering wheel speed, it can ensure sufficient oil supply. The remaining part can be fully supplied to the working device circuit, thereby eliminating the power loss caused by excessive oil supply in the steering circuit, improving system efficiency, and reducing the working pressure of the hydraulic pump. Reduce the serious wear of the excavator hydraulic pump.

(2) Optimize the design of the boom cylinder and hydraulic pump shape
Reduce the system working pressure. Through optimization calculation, the boom cylinder adopts the standard series 80/4. The displacement of the hydraulic pump was increased from 10ML/R to 14ML/R, and the system set pressure was 14MPA, which met the lifting force and speed requirements of the boom cylinder.

(3) Strengthen daily inspection and maintenance
During use, attention should also be paid to the correct use and maintenance of the loader, regular addition or replacement of hydraulic oil, maintenance of the hydraulic oil cleanliness, and daily inspection and maintenance. This will prevent severe wear of the excavator hydraulic pump.