Poor seal of gear pump produces air leak
1) Reduce the internal leakage method: Adjust the movement gap of the pump appropriately. If the pump body and the front and rear end caps are caused by burrs or flatness during assembly, trim the burrs with oil stone; grind the diamond on the flat plate or grind the surface grinder. Grinding, so that the flatness is not greater than 0. 005 mm.
The oil port pipe is not tightly sealed, and the pinion (drive shaft) seal is damaged and air is mixed. First tighten the suction port pipe sealing nut, and then check the sealing ring. If it is damaged, it should be replaced. If the time is too long, the spring inside the sealing ring is too loose to seal the shaft. The spring can be removed and the other end (non-conical end) is ground on the grinding wheel for a short period of time.
2) The oil level is close to or lower than the oil inlet and mixed with air. The inlet pipe is required to be immersed in the 2/3 height of the tank. Otherwise, the inlet pipe should be replaced and the tank should be refueled in time.
High noise and large fluctuations in oil pressure
1) External inspection first. Check the tubing, mounting bracket, and rack for looseness. If it is loose, tighten it; otherwise it will resonate.
2) Tooth deformation or poor contact. For new pumps, the accuracy of the tooth profile may not be high. The method is to replace the gears that meet the requirements or to repair and repair. After reassembly, pay attention to cleaning.
3) Air entering the pump (infiltrating air from the inlet pipe, the pump shaft seal or the pump body pump cover). The oil seal or paper pad can also be replaced by the above 1).
4) The axial clearance between the gear and the end cap is too small. Remove the gear and place it on a flat grinding machine to make it a little bit to make the gap moderate.
Gear pump requirements
1) As a hydraulic power source, the gear pump must use hydraulic oil correctly, paying particular attention to viscosity. If the viscosity is too high, the gear pump will be insufficiently sucked; if the viscosity is too low, the leakage will increase, which will reduce the volumetric efficiency of the pump. At the same time, hydraulic oil is required to have good lubricating properties and chemical stability.
Hydraulic oil can use No. 30 oil in summer and No. 20 mechanical oil in winter. For heavy oil pumps, it is recommended to use hydraulic oil with a thick 30 - 1 or a blue thick 30 - 1. The oil change interval is usually about one year, and is adjusted according to the specific work conditions and environmental conditions.
2) The transmission mode of the gear pump should adopt elastic coupling, and the coaxiality between the two shafts is not more than 0. 1 mm to 0. 2 mm.
3) The inlet filter of the oil inlet filter is 50 μm, and the flow area of the oil filter is 2 times larger than the area of the inlet pipe. The oil inlet pipe and the gear pump coupling shall not leak air. When the oil inlet is flanged, the flange surface shall be kept flat. Use a sealing ring that meets the requirements. The bolts should be tight without leakage to avoid mixing air, causing cavitation and oil leakage.
4) The position of the pump should be as close as possible to the fuel tank. The total height of the oil suction should not exceed 500 mm. Otherwise, it will cause insufficient oil absorption and generate cavitation and noise.
5) The tank weight should be 3 to 6 times the gear pump flow, and the oil tank should also be equipped with an air filter and a hydraulic oil filter.
In the actual work, the hydraulic gear pump is the heart of the hydraulic system, and it is required to attach great importance to its operating state. When the pump fails, it is necessary to find the cause of the fault in time, which requires daily routine inspection. Start, focus on the details, through the diagnostic analysis, find some rules, eliminate the various factors that cause the failure in the early stage of the failure, so that the maintenance work can play a greater role in equipment management and maintenance, and also ensure that the equipment plays a more Great role.
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