1. Vibration and noise
(1) Mechanical vibration and noise
The pump shaft is not concentric with the prime mover. Damage to bearings, transmission gears, couplings, loose mounting bolts, etc. will generate 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, and the resonance can be eliminated by changing the rotation speed of the pump.
(2) Noise caused by liquid flow in the pipeline
When the oil inlet pipe is too thin, the coarse oil filter is blocked or the oil passing ability is weakened, the 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, and pressure shock in the high-pressure pipe, etc. For noise, the fuel tank must be designed correctly, and the oil filter and tubing should be selected.
2. Excessive heating of hydraulic pump
Mainly due to the throttling pressure loss caused by the high-pressure oil flowing through the hydraulic components in the system, resulting in excessive heating of the pump body.
Therefore, the correct selection of the gap between the moving elements, the capacity of the fuel tank, and the size of the cooler can solve the phenomenon of excessive heat generation of the pump and excessive oil temperature.
3. Oil leakage
The oil leakage of the hydraulic pump can be divided into two types: external leakage and internal leakage.
Internal leakage accounts for the largest proportion of oil leakage, and internal leakage between the cylinder and the oil distribution plate is the most important. To this end, check whether the cylinder block and the oil distribution plate are ablated, worn, and installed properly. Check the sliding condition between the shoe and the swash plate, the variable mechanism controls the wear state of the piston, etc. The troubleshooting shall be carried out depending on the inspection situation. If necessary, if parts are replaced, oil seals, thickened or unclogged, the gap between the moving parts shall be properly selected. For example, the clearance between the variable control piston and the rear pump cover shall be 0. 01 ～ 0 ? 02mm.
4. Variable control mechanism operation failure
For manual servo variable pump, sometimes the joystick can not stop, the reasons may be the following:
①The servo spool is stuck, which can clean, grind or replace the spool.
② Variable control piston wears seriously, causing oil leakage and unstoppable.
③ The end of the servo spool is broken, and the spool needs to be replaced.
005mm-0. 015mm。 Servo spool and servo valve sleeve fit clearance is 0. 005-0. 015mm.
The variable speed of the hydraulic variable pump is not enough, because the control pressure is too low, the control pressure should be increased to 3 ~ 5MPa; the control flow is too small, increase the control flow.
