1 Hydraulic Cylinder Inspection and Maintenance

　　For a hydraulic cylinder to fully meet user requirements, in addition to design experience and processing accuracy, correct use and regular maintenance are also essential. Before using the cylinder, air should be released, the buffer adjustment valve should be adjusted to a reasonable position, the oil cleanliness should be checked regularly, dust on the cylinder should be cleaned regularly, and attention should be paid to waterproofing and fire prevention. 1 Inspection and maintenance of seals The piston seal is the main component for preventing internal leakage of the hydraulic cylinder. For lip seals, the lip should be carefully checked for scratches and wear. For combined seals, the wear of the sealing surface should be carefully checked, and then the usability of the seal should be determined. In addition, it is necessary to check whether the static sealing ring between the piston and the piston rod is squeezed. For piston rod seals, the wear of the seals and support rings should be carefully checked. Once defects are found in the seals and guide support rings, seals with the same structural form and suitable material should be selected and replaced according to the structural form of the seals of the hydraulic cylinder being repaired. This can minimize the oil film thickness between the seals and the sealing surface, and reduce the leakage of the seals.

　　2 Cylinder Inspection and Maintenance

　　The inner surface of the hydraulic cylinder and the piston seal are the main factors causing internal leakage of the hydraulic cylinder. If longitudinal scratches occur inside the cylinder, even if a new piston seal is replaced, the fault cannot be effectively eliminated. The inner surface of the cylinder mainly checks whether the dimensional tolerances and form tolerances meet the technical requirements, whether there are longitudinal scratches, and measures the depth of the longitudinal scratches to take corresponding solutions. When the cylinder has slight deformation and shallow scratches, the strong honing process is used to repair the cylinder. The strong honing process can repair cylinders with errors within 2.5 times the original tolerance. It hones the parts with excessive size or shape errors through a strong honing machine, so that the overall size, shape tolerance and roughness of the cylinder meet the technical requirements. When the inner surface of the cylinder is severely worn and there are deep longitudinal scratches, it should be surveyed according to the physical object, and a professional manufacturer should be commissioned to re-manufacture and replace it according to the cylinder manufacturing process. The TS311 anti-friction repair agent can also be used to repair the cylinder. The TS311 anti-friction repair agent is mainly used to repair worn and scratched metal parts. During the repair process, a groove with a depth of more than 1 mm is shaved out on the scratched surface with an alloy scraper, then the groove surface is cleaned with acetone, and the prepared TS311 anti-friction repair agent is applied to the polished surface using a cylinder inner diameter shaping plate, scraped flat with force, ensuring compaction, and higher than the inner surface of the cylinder. After curing, grinding is carried out to leave a finishing allowance, and finally, grinding is used to make the overall size, shape tolerance and roughness of the cylinder meet the requirements. However, the service life and reliability of this repaired cylinder are not high.

　　3 Inspection and Maintenance of Piston Rod and Guide Bush

　　The relative motion pair between the piston rod and the guide bush is the main factor causing external leakage. If the chromium plating layer on the surface of the piston rod peels off or longitudinal scratches occur due to wear, it will directly lead to the failure of the seal. Therefore, the surface roughness and form tolerance of the piston rod should be carefully checked to see if they meet the technical requirements. If the piston rod is bent, it should be straightened to meet the requirements or surveyed according to the physical object and manufactured by a professional manufacturer. If the plating on the surface of the piston rod is worn, scratched, or partially peeled off, the plating can be ground off, and the surface can be re-plated and processed.

　　4 Inspection and Maintenance of Buffer Valve

　　For valve-buffered hydraulic cylinders, the wear of the buffer valve spool and valve seat should be carefully checked. Once increased wear or seal failure is found, it should be replaced. The spool and valve seat can also be repaired by using abrasives for matching.