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2. The oil seal was flushed out
(1) The gear pump rotates incorrectly. When the rotation of the pump is incorrect, the high pressure oil will directly lead to the oil seal. Since the low pressure skeleton oil seal can only withstand a maximum pressure of 0.5 MPa, the oil seal will be washed out.
(2) Gear pump bearings are subjected to axial forces. The axial force generated is often related to the over-tightening of the shaft end of the gear pump shaft and the coupling sleeve. That is, the pump is hammered with the hammer or hard-drawn through the mounting screw to apply a backward axial force to the pump shaft when the pump is installed. As the shaft rotates, this backward axial force will force increased wear in the pump. Because the inner surface of the gear pump is sealed by the gear end face and the end face of the sleeve, when the axial seal face wears badly, the internal axial seal of the pump will produce a certain gap, resulting in the communication of the high and low pressure oil chambers to make the oil seal flush out. . This situation occurs more in the dump truck industry, mainly due to the irregular size of the coupling bushes on the main engine.
(3) The gear pump is subjected to excessive radial forces. If the coaxiality of the gear pump is not good, the radial force of the pump will exceed the limit of the oil seal, which will cause the oil seal to leak oil. At the same time, it also causes damage to the floating bearings inside the pump.
3. Can't afford pressure or pressure
The occurrence of this phenomenon is mostly related to the cleanliness of the hydraulic oil. If the oil is not selected correctly 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 fluids containing additives should be used to prevent oil oxidation and bubble formation. The viscosity standard of oil is (16~80)×10-6m2/s. The filtering accuracy is: the input oil circuit is less than 60μm. By observing the bushings and side plates of the defective gear pump, it was found that if the cleanliness of all the oils is different, it will lead to obvious groove marks on the surface of the friction pair, and only a uniform surface mark will be produced on the normal worn gear pump sealing surface.
4. The traffic does not meet the standard
(1) The oil inlet filter element is too dirty to absorb enough oil.
(2) The mounting height of the pump is higher than the self-priming height of the pump.
(3) The suction tube of the gear pump is too thin to cause large suction resistance. The general maximum suction flow rate is 0.5 to 1.5 m/s.
(4) The leak in the suction port joint causes insufficient oil pump suction. Observe whether there is a leak in the system by observing the presence of air bubbles in the tank.
5. Gear pump burst
Aluminum alloy gear pump pressure capacity of 38 ~ 45MPa, in the absence of manufacturing defects under the premise of the gear pump burst is definitely caused by the instantaneous high pressure.
(1) The foreign matter in the oil pipeline is blocked and the pressure rises indefinitely.
(2) The pressure of the safety valve is adjusted too high, or the opening and closing characteristics of the safety valve are poor, and the response is lagging, so that the gear pump is not protected.
(3) If the system uses multiple directional control valves to control the direction, some multi-way valves may have negative openings. This will cause the gear pump to smash due to the dead point boost.
6. Heating
(1) System overload, mainly manifested in excessive pressure or speed.
(2) Poor cleanliness of the oil, increased internal wear, reduced volumetric efficiency, and leakage of oil from the internal gap 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 to 8 m/s.
7. If the gear oil pump is used for too long, the gear oil pump gear and the pump body are worn too much, the seal is damaged, and the internal clearance is too large. It is recommended to replace the new gear oil pump.
Reason why the sprinkler gear pump does not step up
If you find that the gear pump does not come on during commissioning, first check that the direction of rotation of the gear pump is correct. The gear pump has left and right rotations. If the direction of rotation is incorrect, the pressure oil formed by the volume difference generated by the internal gear meshing will cause the oil seal to be damaged and leak oil. Secondly, check whether the oil filter of the gear pump inlet port is blocked, which may cause difficulty in sucking oil or oil, and may cause the suction hose to be sucked.