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Analysis and Solutions for Oil Leakage from the Gear Pump Seal in Loaders. \"Oil leakage from the gear pump\" refers to the situation where hydraulic oil penetrates through the skeleton seal and leaks out. This phenomenon is widespread; manufacturers are highly concerned as oil leakage from gear pumps severely affects the proper operation of loaders, as well as the reliability of these gear pumps and causes environmental pollution. To facilitate problem resolution, an analysis is now conducted on the causes and control methods of oil leakage from the gear pump seal. I. Impact on the quality of component manufacturing (1) Quality of oil seals. Issues such as an unsuitable geometry of the oil seal lip or a too-loose compression spring can cause leakage during the airtightness test, leading to oil leakage from the gear pump once it is installed in the main unit. At this point, the oil seal should be replaced, and its material and geometry should be checked (there is a significant quality difference between domestic oil seals and advanced foreign ones). (2) Machining and assembly of gear pumps. If there are issues with the machining or assembly of the gear pump, resulting in the rotation center of the gear shaft not being aligned with the shoulder of the front cover, it will cause uneven wear of the oil seal. At this time, the symmetry and displacement of the pin holes relative to the bearing holes in the front cover, as well as the coaxiality of the frame oil seal with the bearing holes, should be checked. (3) Seal ring material and machining quality. If there are problems in this regard, it can cause cracks and scratches on the sealing ring, leading to poor or even failed secondary sealing. As a result, pressure oil enters the skeleton oil seal area (the low-pressure channel), causing oil leakage from the oil seal. At this time, the material of the sealing ring and its manufacturing quality should be checked. (4) The machining quality of the variable displacement pump. According to the feedback received from the vehicle manufacturers, the oil leakage problem of the gear pump seals when it is assembled with the variable speed pump is quite severe; therefore, the manufacturing quality of the variable speed pump also has a significant impact on oil leakage. The variable-speed pump is mounted on the gearbox output shaft, and the gear pump is also mounted on this shaft via the flange of the variable-speed pump. If the runout (verticality) of the flange surface of the variable-speed pump with respect to the rotation center of the gear is out of tolerance, it will cause the rotation center of the gear shaft not to align with the center of the oil seal, thereby affecting the sealing performance. During the machining and prototyping of variable-speed pumps, it is necessary to check the coaxiality of the rotation center with respect to the shoulder, as well as the runout of the rotation center relative to the end face of the shoulder. Figure 1 Cross-sectional view of the CBG gear pump. (5) The return oil channel in the front cover between the skeleton oil seal and the sealing ring of the CBG gear pump is blocked, resulting in an increase in pressure at this location, which in turn causes the skeleton oil seal to fail. Through these improvements here, the oil leakage problem of the pump has been significantly reduced. Its structural form is shown in Figure 1. II. Impact of the installation quality of the gear pump and the main unit (1) The installation requirement for the gear pump and the main unit is that the coaxiality should be less than 0.05. Typically, the working pump is installed on the variable-speed pump, which in turn is mounted in the gearbox. If the runout of the end face of the gearbox or shift pump relative to the rotation center of the spline shaft is out of tolerance, this results in cumulative errors, causing the gear pump to operate at high speeds…………Read more