When oil leakage is found, check the sealing area first to see if there is any abnormal phenomenon, usually there are two situations to judge.

Category I: Seals without abnormalities

1. Leak-free at low pressure and high pressure, resulting in poor surface roughness of assembly - --- Seals with lower hardness for improving surface roughness to 3.2-6.3 umry

2. The oil ring of piston rod becomes larger, and drops of oil will be dripped on each stroke. The reason is that the lip of the dust ring scrapes off the oil film and replaces the type of the dust ring.

3. There are two reasons why there is no oil leakage at low temperature and high temperature. One is that the eccentricity is too large. The other is that the material selection of seals is not appropriate. The problem can be solved by selecting cold-resistant seals.

Category 2: Seals with abnormal conditions

1. The surface of main oil seal is hardened and the sliding surface is broken. The reason is that the working pressure of abnormal high speed is too high.

2. The surface of the main oil seal is hardened, and the whole seal is broken and broken. The reason is that the abnormal rise of the temperature of the deteriorated oil in hydraulic oil causes ozone damage to the seal and oil leakage.

3. The wear of the main oil seal surface is as smooth as a mirror; the reason is that the pressure is too high and the travel is small in fretting age.

4. The mirror wear of the main oil seal surface is not uniform. The seals show swelling phenomenon. The reason is that the side pressure is too large and the eccentricity is too large. The improper oil and cleaning fluid are used.

5. The sliding surface of main oil seal has damage and abrasion marks. The reasons are poor plating, improper material selection and impurities in rough piston rod with rust point matching surface.

6. There are cracked scars and indentations on the top of the lip of the main oil seal. The reasons are improper assembly chamfering, installation and storage methods.

7. There are indentations on the sliding surface of the main oil seal. The reason is that there are foreign debris.

8. There are cracks in the lip of the main oil seal. The reasons are improper use of oil, high or low working temperature, high speed of back pressure and high frequency of pulse pressure.

9. The main oil seal is decayed by carbonization and coke burning. The reason is that the residual air produces adiabatic compression.

10. There are cracks in the heel of main oil seal during extrusion. The reason is that the pressure is too high, the extrusion clearance is too large, the supporting ring is used properly, and the design of installation groove is unreasonable.