Analysis and solution of pressure relief defects of mini excavator arms

If the pressure relief of the arms is not very serious, it is generally a normal phenomenon. It depends on how long it takes for the arm to fall to the ground when the arm is raised to the highest and the forearm and bucket are straightened. The normal pressure relief standard of a small excavator is 50ml per hour. If the arm of a small excavator drops automatically during operation, and the drop speed is very fast, exceeding the specified drop distance (the bucket tooth drops more than 95mm in 5 minutes), this is the pressure relief of the arms of the small excavator, also called arm drop.

1. What is the reason for the pressure relief of the arms of a small excavator?

1. The pressure relief of the arms of a small excavator is mainly caused by the movement of the boom, dipper rod or bucket cylinder when the small excavator is fixed.

2. When the multi-way valve is in the middle position, due to the effect of the gravity of the operating equipment, a certain pressure is generated in the oil cylinder. This pressure is transmitted to the multi-way valve through the pipeline. Because there must be a certain gap between the valve cores of the multi-way valve, a certain leakage is formed, resulting in the pressure relief (arm-dropping) phenomenon. Therefore, the small excavator indicates in the manual that the bucket must be supported when the excavator is not working.

3. In addition, if the arm-dropping phenomenon is serious in some parts (the oil temperature is about 45℃, and the bucket teeth drop more than 95mm in 5 minutes), it may be due to the multi-way valve being stuck. Please clean the multi-way valve.

4. First, look at the color of the inner core of the arm-dropping hydraulic shaft under natural light. If it is blue-black or colorful, it means that the oil cylinder is leaking oil, which is a problem with the oil seal. Just change a set. If the oil seal is normal, the inner core is silver-white.

5. The oil seal cannot or the oil seal of the multi-way valve is leaking.

6. The hydraulic pump seal is not good, commonly known as "unloading oil". Just change the seal ring of the hydraulic pump.

2. Solutions to relieve pressure on the arms of small excavators

1. Analyze the temperature of the working environment of the small excavator and the maximum load that the small excavator can accept.

2. After making an accurate judgment, select the appropriate brand hydraulic oil according to the ambient temperature of the small excavator and the load conditions of the small excavator.

3. Replace and maintain the filter element regularly, and pay attention to purchasing genuine hydraulic oil.

4. When the arm drops during operation, you can first adjust the arm pressure to a lower level (smaller than the normal pressure) to observe whether the arm will fall quickly?

5. If the falling speed is very fast, it is recommended to replace the arm oil seal.

6. If the defect still exists after replacing the oil seal, it is necessary to check the arm oil return safety valve.

7. Check the pressure value of the excavator pump valve group.