Hydraulic pump technical performance is usually referred to as the pressure and flow of the pump. Wear, oil pollution, etc. in use, can result in volumetric efficiency, decrease in pressure and reduction in flow. Performance is a slow operation in the system (hydraulic cylinder, motor) operation, powerless, and simultaneous hydraulic pumps generate noise, leak and fever until it is not turned (card death).
1. The pump is operating normally, and the implementation is weak.
In this case, the pressure value of each executable element is measured with a pressure gauge, check the working condition of the main safety valve, the standard pressure value of the control system, can quickly determine whether the output pressure and flow of the pump are normal.
2, pump vibration and noise
1. Forced vibration caused by power input and fixed connections
(1) The engine is insufficient, and the operation is not smooth.
(2) Wear the spline of the pump input shaft, transmission of the connection disk, damages the damping disk, the transmission shaft crosshead universal joint wear.
(3) The fixed bolt of the pump is loose due to long-term operation, and the stent is fixed.
(4) The pump is equipped with the engine to install the coaxial degree to increase the additional load generated by eccentric operation.
2. Pump itself vibration and noise
(1) Because of the lack of oil, the pump shell is low-pressure in the oil, which causes vibration and noise in a large amount of air in the oil pump.
(2) The oil-opening filter is blocked or the oil pipe rubber aging.
(3) Due to the wear of the pump's distribution plate or oil inlet valve, the sealing property has caused insufficient oil volume, causing the pump flow to be performed to generate vibration.
(4) The winter oil is low, the oil has a large viscosity, and noise is generated.
(5) The pumping oil seat is loose, the oil supply spring is damaged, the oil-proof valve seat is loose, the oil-proof valve spring breaks or shortcomings of the elasticity, etc., the pump high pressure cavity is difficult to seal, causing some plunger oil pump weakness, and the flow is uneven. Result in pump vibration.
(6) High and low pressure valve seat screw holes on the valve-type distribution plate, due to poor processing quality or long-term use, size is seven, or the iron filings is not completely washed, resulting in the rear valve surface after the new valve is not loaded. Balance, causing the valve to be sealed while vibrating.
(7) The high-voltage outlet valve is venting the air of the plunger cavity, and the exhaust space is blocked to cause vibration.
(8) The plunger is caused by a strap and a cylinder, and a cylinder is partitioned and cracking occurs.
(9) On the crankshaft radial plunger pump, the connecting rod and the crank gap are extremely different, and the gap between the connecting rod and the connecting rod pin, which can cause impact vibration.
(10 The cylinder sizes of the radial plunger pump is extremely vibration.
(11 Pump shaft supporting the positioning accuracy of the bearing, the inner outer outer outer outer outer ring of the bearing does not meet the design requirements, the axial positioning adjustment is unreasonable, and the pump will cause vibration and noise.
(12) The seven column pores in the swash shaft pump rotating the cylinder are too large, and the dimensional precision of each well is low, and vibration and noise occur when it is running at high speed.
3. Load (load) or the like caused by vibration load and control element speed regulation is unreasonable
If the speed valve and the back pressure valve are imbalance in the pressure, the system vibration is caused: the speed limit valve or back pressure valve causes vibration: pilot system pump failure results in suction to cause main pump vibration: oil pump oil-proof steel tube too Long, fixed is not strong, causing mutual impact.
3, leakage and fever
Low pressure leak
Also known as the leakage, the fault is intuitive, easy to exclude.
(1) Pump shaft end oil seal damage and rubber aging.
(2) The pump shaft is unreasonable during assembly, and the sealing surface of the oil seal is injured.
(3) In the end cap of the oil pipe, the sealing is damaged, and the fixed bolt is loose.
2. High pressure leakage
It is also known as the internal leak. The reasons are:
(1) In the pump of the valve-type distribution, high and low pressure valves are not sealed. Among the pumps of the distribution plate, the distribution plate is worn or severely straighted between the cylinder.
(2) In the pump of the valve-type distribution, the cylinder is distorted by the cylinder and the valve body studs due to the manufacturing or repair of the mounting, which will cause the valve body to distort, the O-ring loaded or the poor quality, which will cause the cylinder and the valve body. Sealing surface leakage. Among the pumps of the distribution disk distribution, the central spring is damaged or elastic, and the axial gap is too large, and the cylinder blocks and the distribution plate will lose sealing.
(3) The gap between the plunger and the cylinder is too large, and the normal sealing oil film is destroyed. High pressure leakage and fever are associated, and the gap will inevitably cause leakage, and the change in the gap is changed to heat energy release. With the growth of hydraulic pumps, the inner leakage makes the pump reduce the volumetric efficiency of the pump, the plunger is biased, and the mechanical resistance increases the efficiency, the resistance increases and the pressure can be lowered, that is, the oil temperature rise of the hydraulic pump, the system is weak Slow motion, these phenomena have occurred in the latter stage of the pump. When natural wear makes the sealing surface, the gap is sharply increased, the amount of leakage is greatly increased, the fever is severe, and the excavator must be repaired or replaced with the pump assembly.
4, the effect of hydraulic oil
Hydraulic oil is a carrier that delivers pressure energy. Normal oil has the increase in working hours, the environmental impact and pollution, and various performance indicators will decline. The effect of moisture, air, cleaning agent, acid, oxide, etc. causes rubber parts to produce residual cement, which reduces the lubrication performance of hydraulic oil, and attenuate the bonding temperature index. The discoloration and viscosity changes of hydraulic oil have the greatest impact on the pump.
In the full hydraulic excavator hydraulic system failure, the hydraulic pump has the highest failure frequency, and the failure caused by oil pollution accounts for about 70% to 75% of the total number of disavivable hydraulic systems. For contaminated oils, it must be thoroughly replaced to ensure that the hydraulic excavator is working properly.
