Hengsheng Product Classification
(1) The gear pump is turned in the wrong direction. When the rotation of the pump is incorrect, the high-pressure oil will directly pass to the oil seal. Because the low-pressure skeleton oil seal can only withstand a pressure of up to 0.5 MPa, the oil seal will be washed out. (2) The low-pressure gear oil pump bearing is subjected to axial force. The generation of axial force is often related to the over-tightening of the gear pump shaft extension with the coupling sleeve, that is, the pump shaft is hit with a hammer during installation or the mounting screw is pulled hard to subject the pump shaft to a backward axial force. As the shaft rotates, this backward axial force will force increased wear in the pump. Because the inside of the low-pressure gear oil pump is sealed by the gear end face and the shaft sleeve end face, when the axial seal end face is heavily worn, the internal axial seal of the pump will generate a certain gap, resulting in high-low pressure oil chamber communication and the oil seal rush Out. This situation occurs more often in the dump truck industry, mainly due to the irregular size of the coupling sleeve on the host. (3) The low-pressure gear oil pump is subjected to excessive radial forces. If the coaxiality of the gear pump is not good, it will cause the radial force of the pump to exceed the bearing limit of the oil seal and cause oil leakage from the oil seal. At the same time, it will cause damage to the floating bearings inside the pump.
3. Can't build pressure or stress is not enough
The occurrence of this phenomenon is mostly related to the cleanliness of the hydraulic oil. If the oil is incorrectly selected or the cleanliness of the oil in use does not meet the standard requirements, it will accelerate the internal wear of the pump and cause the leakage. Therefore, mineral hydraulic oil containing additives should be used, which can prevent the oil from oxidizing and generating air bubbles. The viscosity standard of the oil is (16 ～ 80) × 10-6m2 / s. The filtration accuracy is: the input oil circuit is less than 60цm. By observing the faulty low-pressure gear oil pump's shaft sleeve and side plate, it is found that if all oils have poor cleanliness, it will cause obvious groove marks on the surface of the friction pair, and normal wear of the gear pump sealing surface will only produce uniform surface marks.
4. The flow does not meet the standard
(1) The oil inlet filter is too dirty, and the oil absorption is insufficient. (2) The installation height of the pump is higher than the self-priming height of the pump. (3) The suction pipe of the gear pump is too thin, resulting in large suction resistance. Generally, the maximum oil absorption velocity is 0.5 ～ 1.5m / s. (4) Air leakage at the oil inlet connector causes insufficient oil suction by the oil pump. You can determine whether the system is leaking by observing the air bubbles in the fuel tank.
5. Gear pump bursts
The aluminum alloy gear pump has a pressure resistance of 38 to 45 MPa. Under the premise of no manufacturing defects, the low-pressure gear oil pump burst must be caused by transient high pressure. (1) Foreign matter is blocked in the oil outlet pipe, causing the pressure to rise infinitely. (2) The pressure of the safety valve is too high, or the opening and closing characteristics of the safety valve are poor, and the response is delayed, making the gear pump unprotected. (3) If the system uses a multi-way reversing valve to control the direction, some multi-way valves may have negative openings, which will cause the gear pump to be damaged due to the dead point pressure increase.
6. Fever(1) The system is overloaded, which is mainly manifested in excessive pressure or speed. (2) Poor oil cleanliness, increased internal wear, and reduced volumetric efficiency. Oil leaks and throttles from the internal gap of the low-pressure gear oil pump to generate heat. (3) The oil outlet pipe is too thin and the oil flow rate is too high. Generally, the oil flow rate is 3-8m / s.