1. Vibration and noise
(1) Mechanical vibration and noise
The pump shaft and prime mover are not concentric, the bearing, transmission gear and coupling are damaged, and the assembly bolts are loose, which will produce vibration and noise.
If the rotation frequency of the pump is the same as the natural frequency of the combined pressure valve, resonance will occur. The resonance can be eliminated by changing the speed of the pump.
(2) Noise generated by liquid flow in pipeline
When the oil inlet pipe is too thin, the primary oil filter is blocked or the oil passing capacity is weakened, and air is sucked into the oil inlet pipe; The oil viscosity is too high, the oil level is too low, resulting in insufficient oil absorption, pressure impact in the high-pressure pipeline, etc., which will produce noise. The oil tank must be designed correctly, and the oil filter and oil pipe must be selected.
2. Excessive heating of hydraulic pump
It is mainly due to the throttling pressure loss when the high-pressure oil in the system flows through each hydraulic element, resulting in excessive heating of the pump body.
Therefore, the correct selection of the gap between moving elements, the capacity of oil tank and the size of cooler can solve the phenomenon of excessive heating of pump and excessive oil temperature.
3. Oil leakage
The oil leakage of hydraulic pump can be divided into external leakage and internal leakage.
Internal leakage accounts for the largest proportion of oil leakage, and the internal leakage between cylinder block and oil distribution plate is the most important. Therefore, check whether the cylinder block and oil distribution plate are ablated and worn, and whether the installation is appropriate. Check the sliding condition between the sliding shoe and the swashplate, and the wear state of the variable mechanism control piston. Troubleshooting depends on the inspection. If necessary, replace parts, oil seals, thicken or dredge the oil leakage pipe holes, and properly select the clearance between moving parts. For example, the matching clearance between variable control piston and rear pump cover shall be 0.01 ~ 0.02mm.
4. Variable control mechanism operation failure
For manual servo variable displacement pump, sometimes the control lever cannot stop. The reasons may be as follows:
① The servo spool is stuck, which can be cleaned, ground or replaced.
② The variable control piston is seriously worn, causing oil leakage and unstoppable.
③ The end of the servo valve core is broken, and the valve core needs to be replaced.
The fit clearance between servo valve core and servo valve sleeve is 0.005-0.015mm.
The change speed of hydraulic variable displacement pump is not enough because the control pressure is too low, so the control pressure should be increased to 3 ~ 5MPa; The control flow is too small, increase the control flow.
