The companys cylinder liner generally applies the materials of wear-resistant alloy cast iron containing chromium or boron, such as HT25-47, HP-CuCrMo, etc. The inner surface of the cylinder liner is also sometimes chrome plated (loose hole chrome plating, chrome plated toil storage outlets), and nitrating or phosphating treatment to improve wear resistance. The inner surface hardness of cylinder liner is usually greater than HB200, and has a good match with the hardness of piston ring. The inner surfaces would have appropriate roughness to make it have a certain oil storage capacity and running-in performance. The inner surface should be of sufficient roundness and cylindricity accuracy, and the mounting support should have a high positional accuracy against the inside bore center.

The inner surface of cylinder is easy to wear because of high temperature and high pressure gas and contact with pistons at high-speed motion. In order to improve the wear resistance and prolong the service life of the cylinder, different cylinder structure and surface treatment methods are provided. There are three types of cylinder structures: no cylinder liner type, dry cylinder liner type, wet cylinder liner type.

Non-cylinder liner type means that no cylinder liner body is embedded, and the cylinder body is directly worked out of the body, which has the advantages of shortening the cylinder center distance andreducingthe size and the weight of the body. But the cost is high.

Dry cylinder liner is not in contact with the coolant, with the wall thickness of 2~3mm, the outer surface and cylinder liner seat holeinnersurface must be refined to ensure the necessary precision and easy removal, which has the advantages of high rigidity, small central distance of the cylinder, light weight and simple processing technology. The disadvantage is that the heat transfer is poor, the temperature distribution is uneven, and the local deformation is easy to occur.

The outer wall of wet cylinder liner is in direct contact with the coolant,withthe wall thickness of 5~8mm,whichrealizes the radial positioningbyusing the upper and lower positioning ring, and realizes axial positioning with the help of corresponding bearing surface mating between the upper flange of cylinder liner and the top of the body, which has the advantages of the absence of sealed water jacket on the body, easy casting, good heat transfer, even temperature distribution and easy repair without removing theenginefromthe vehicle when replacing the cylinder liner. But the body stiffness is poor, and easy to leak.