First of all, there will be oil in the friction part of the machine during the operation. In order to prevent the oil from being scratched away from the mechanical space, the chassis and hydraulic oil seal are used. Besides the oil, it is also necessary to prevent the leakage of a pile of liquid medicine and the invasion of dust, sand, dust and other dust from the outside. Therefore, chassis and hydraulic oil seal are also used at this time. At the same time, pay attention to the structural quality of the hydraulic framework oil seal. If it is found that the geometric shape of the oil seal lip design is not qualified in the application, it will cause air leakage in the air tightness test. After the subsequent gear pump is installed in the main engine, it is easy to cause the oil seal to be broken down and oil burst. Hydraulic system is related to hydraulic cylinder, control valve, gear pump and other important parts. Before the operation of the hydraulic system, it is necessary to check the cleanliness of the components to ensure that the subsequent work of the hydraulic framework oil seal and sealing elements can go in effectively and continuously without causing seal failure. At the same time, there are welding slag, flash inside the hydraulic cylinder and burr in the oil tank and pipeline. These pollution factors will cause friction and wear failure of gear pump and oil seal. According to different parts, the sealing body is divided into cutting edge, sealing lip, etc. The outer part of the oil seal is a round wooden barrel, which is used for ultra dense static sealing. At the same time, a rubber outer edge of the inner metal skeleton introduced from abroad is also used; the outer edge of the exposed metal skeleton, which mostly needs polishing and plating anti-corrosion coating.