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No oil from vane pump? With the outlet pressure does not go up?

Update:18-08-2020
Summary:

Almost all the causes of the failure of "vane pump can […]

Almost all the causes of the failure of "vane pump can not produce oil" may be the reason that the pressure can not go up or there is no pressure at all
1. There is poor contact between the oil distribution plate and the end face (fixed surface) of the housing, and there is a large dirt between them, so that part of the pressure oil in the pressure oil chamber flows into the low-pressure area through the gap between them, and the output flow is reduced. Therefore, it should be disassembled and cleaned to make it close.
2. The end face (sliding surface) of oil distribution plate and rotor is roughened, which has serious wear, large internal leakage and insufficient output flow. The roughening high point can be polished with coarse (not too coarse) sandpaper, and then the dent can be removed with fine abrasive cloth, and then used after polishing.
3. The inner surface of stator (inner curve surface) is roughened and worn, and the scuffing scratch of blade top circle and inner curved surface bracket of stator hole leaks into oil absorption area, resulting in insufficient output flow. Therefore, metallographic sandpaper can be used to grind inner surface of stator.
4. The blade and back drill assembly (pump core) are installed reversely
5. There are some casting defects such as blowhole, sand hole and shrinkage porosity in the pump body, which are broken down, so that the high and low pressure cavities are partially connected, and oil cannot be absorbed. At this time, the vane pump may be replaced.
6. If the axial clearance is too large, that is to say, the difference between the thickness of the rotor and the stator and the depth of the hole in the vane pump is too large, or the paper cushion is added during the repair, so that the axial clearance is too large, the internal leakage is too large, and the internal leakage is increased, and the output flow is reduced.
7. If the variable mechanism is not adjusted properly or has problems, it can be handled as appropriate after finding out the causes
8. The end face of oil distribution plate is worn or grooved, with large internal leakage and insufficient output flow.
9. If the oil filter is blocked, or the filtering accuracy is too high, no oiling or little oiling (depending on the degree of blockage), it can be disassembled and cleaned.
10. The viscosity of hydraulic oil is too low, especially for small capacity vane pump. When the oil viscosity is too low or the oil temperature rise is too high, the oil from vane pump can not be loaded to rise to the required pressure. This is due to the increase of internal leakage caused by low oil viscosity and temperature rise.
11. For the variable vane pump with limited pressure, when the pressure regulating screw is not adjusted well and exceeds the pressure limit, the flow rate decreases significantly, and the pressure is difficult to be higher after entering the system.
12. After the internal parts of the vane pump are worn, the pressure can be increased at low temperature, but after the equipment has been running for a period of time, the oil temperature will rise, and the internal leakage caused by wear will be large, and the pressure loss will be large, and the pressure will not go up at this time (the maximum can not be reached). If you want to adjust it rigidly (tighten the overflow valve), the needle will vibrate violently. At this point can be sure that the blade pump is seriously worn, if a new vane pump, the pressure will be up immediately.
13. The internal surface of the stator is scratched, resulting in poor contact between the top of the blade and the inner surface of the stator, the internal leakage is large, the flow rate is reduced, and the pressure is difficult to adjust. At this time, the inner curved surface of the stator should be polished or the stator should be replaced.
14. For medium and high pressure vane pump with pressure reducing valve, if the output pressure of pressure reducing valve is adjusted too high, it will lead to early wear of blade top and stator inner surface due to excessive contact stress. The leakage in the vane pump is large, the output flow is reduced, and the pressure can not go up.

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