Construction machinery and equipment all need hydraulic cylinders, and hydraulic cylinders all need hydraulic seals. A common hydraulic sealing ring, also called skeleton seals, which is to prevent the leakage of the working sealing medium and the external impurities attached to the piston rod and enter the hydraulic cylinder.The seals commonly used in hydraulic cylinders are divided into the following categories: dust seals, piston seals, buffer seals, guide support rings, end cover seals and piston seals. Dust seals are installed on both sides of the end cover of the hydraulic cylinder to prevent external pollutants from entering the hydraulic cylinder. According to the installation method, they can be divided into snap-in type and press-in type.