Why do hydraulic cylinders change color on excavators?

In the daily operations of excavators, hydraulic cylinders, as a key actuator, directly affect the work efficiency of the excavator. However, the color change of hydraulic cylinders is a common issue that has drawn the attention of operators and maintenance personnel.This color change process is not due to a chemical change in the cylinder itself but rather a colored film covering the cylinder surface. The following are the main reasons for the color change of hydraulic cylinders:

1. High Temperature of the Hydraulic System

The hydraulic system operates at high temperatures, especially in cold seasons. The piston rod frequently contacts the low-temperature environment at high temperatures, and the sudden drop in temperature can cause discoloration.

2. Hydraulic Oil Quality Issues

If non-manufacturer-specific hydraulic oil is used during the maintenance cycle, the quality and performance of the extreme pressure and anti-wear additives in the hydraulic oil may differ, leading to piston rod discoloration.

3. Seal and Additive Effects

The seals and additives in the hydraulic oil will adhere to the cylinder rod at high temperatures, causing it to turn blue; the lead-containing additives in the sprayed material of the wear-resistant sleeve will adhere to the cylinder rod at high temperatures, leading to blackening.

4. Piston Rod Plating Issues

If the temperature control during the plating process of the piston rod is uneven, it may cause cracks in the plating layer, resulting in discoloration during use.

5. Poor Performance of Hydraulic Oil Radiator

If the hydraulic oil radiator does not work properly, it may cause the hydraulic oil to overheat, leading to cylinder discoloration.

In response to the above reasons, the following measures can be taken to solve or alleviate the problem of hydraulic cylinder discoloration:

1. Regularly Replace Hydraulic Oil

Use hydraulic oil produced by reputable manufacturers and replace it regularly to ensure the oil's resistance to oxidation and thermal stability.

2. Inspect and Maintain Radiators

Regularly check the working condition of the hydraulic oil cooling device and clean it to ensure good cooling effects.

3. Avoid Using Non-Dedicated Hydraulic Oil

Do not mix different brands of hydraulic oil to avoid interactions between additives that may cause discoloration.

4. Check Seals and Wear-Resistant Sleeves

If the cylinder discoloration is severe, it may be necessary to replace the seals and wear-resistant sleeves and avoid high temperatures of hydraulic oil.

5. Pay Attention to the Quality of Piston Rod Plating

Ensure that the temperature control during the plating process of the piston rod is uniform to avoid discoloration due to quality issues.

Conclusion

Although the color change of hydraulic cylinders is a common issue, it can be effectively controlled and resolved through proper maintenance and care. This not only helps reduce equipment failure rates, but also saves companies maintenance costs and downtime.