Generally speaking, after running for a period of time, bucket wheel machines need to undergo routine inspections to ensure that the equipment can operate safely. During an inspection of the bucket wheel machine at a certain factory, it was discovered that the machine, which had been in operation for 5 years, was gradually experiencing some abnormal problems, such as noise in the hydraulic pump, leakage in the tilting cylinder, and insufficient power. If these small faults that occurred in the hydraulic system of the bucket wheel machine were not eliminated, they would inevitably bring great safety hazards to the operation of the entire bucket wheel machine over time. For this reason, the technical personnel of the factory conducted a detailed investigation of this bucket wheel machine, analyzed the cause of the hydraulic system failure, and carried out troubleshooting and treatment. This article lists some of the fault handling measures for peer exchange and discussion.
1. Analysis and Treatment of Fault Causes of Axial Piston Pump
The hydraulic pump used in our bucket wheel machine is a 25SCY14-1B PVT38-2R1C axial piston pump. There are many faults and causes of hydraulic pump failures, but in practice, the main reasons for failures are:
1.1 Common fault phenomena and cause analysis
A. Malfunctions caused by the hydraulic pump itself. Axial piston pumps are positive displacement hydraulic pumps, which require machining accuracy to meet certain requirements, such as surface roughness, fit clearance, form and position tolerances, and contact stiffness. After a period of use, some machining quality problems of the pump are easily exposed, mainly manifested by the destruction of technical accuracy requirements, aging of seals, internal leakage in practice, and insufficient flow when the load is high. Such faults are not easy to eliminate. Therefore, when the cause of the fault is not clear, the pump is generally not easily disassembled.
B. Malfunctions caused by external factors In practice, external factors are the main cause of pump failures, including: ① hydraulic oil. Oil is the medium that maintains the normal operation of hydraulic systems, and the quality of oil directly determines the stability of system operation. Excessive oil viscosity can increase oil suction resistance, leading to cavitation and insufficient pressure and flow. During high temperature seasons, the temperature of the oil pump increases, and the sealing components are prone to aging; Low oil viscosity can increase leakage, reduce volumetric efficiency, and easily inhale air, causing impact or "crawling". ② Installation of the pump. The connection between the pump shaft and the drive motor shaft should have good coaxiality, with a coaxiality deviation of 0.02mm. If the coaxiality exceeds the tolerance, it can cause irregular noise and vibration. The sealing of the pump's suction and discharge pipe joints must be good to prevent air from entering.
1.2 Handling measures
① The plunger pump has severe noise and vibration. Troubleshooting process. ② Adopting large capacity oil suction filters and large-diameter oil suction pipes to reduce local resistance in the pipeline, prevent air from entering the system and forming voids, and eliminate rapid changes in oil pressure inside the pump. ③ To absorb the flow and pressure pulsation of the pump, an accumulator or muffler can generally be installed at the outlet of the pump to absorb the impact caused by pulsation. ④ The pump and motor should be installed on the oil tank and rubber vibration damping pads should be used, with a vibration value of ≤ 0.04mm~0.06mm. The coaxiality deviation of the coupling is within a radial range of ≤ 0.03mm and an axial range of ≤ 0.10mm. ⑤ An oil resistant rubber hose is used to isolate the pipeline from the pump body, reducing the amplification phenomenon caused by slight vibrations of the pump body through the pipeline.
2. Analysis and treatment of common faults in pitch oil cylinder
Our factory's bucket wheel machine hydraulic pitch cylinder is a DG-JB280E-E1-L2 double acting cylinder with a diameter of 280mm, a stroke of 1500mm, a working pressure of 16Mpa, and a 350/250-1880/3365 single acting cylinder.
2.1 Common faults and cause analysis
A. Oil cylinder leakage
Oil leakage is a common fault in the pitch oil cylinder of bucket wheel machines, which is mainly caused by the wear and tear of seals, rupture, or permanent deformation due to compression after use; Leakage occurs at the joint between the cylinder barrel and cylinder head; Due to vibration, the connection between the inlet and outlet pipes becomes loose and leaks occur. The three types of leaks mentioned above are mainly external leaks, which are easy to check and are common in production practice. The most dangerous type is internal leaks, which are difficult to detect and pose a significant threat to equipment. In severe cases, the oil cylinder may not be able to move and the bucket wheel machine may become paralyzed. To detect internal leaks, it is necessary to check the upper and lower chambers of the oil cylinder. If there is a pressure difference, it indicates internal leaks. If there is a serious internal leak, the oil cylinder needs to be disassembled and overhauled.
B. Insufficient output or decreased speed of the oil cylinder during operation
During the operation of the oil cylinder, insufficient output often occurs, resulting in the cantilever not lifting or slowing down the speed compared to normal operation. The main reasons are: ① excessive clearance between the piston cup or damaged seals, leading to internal leakage of the oil cylinder. ② The clearance between the piston cups is too small, and the seal is too tight, which increases the resistance to movement and damages the seal. ③ The hydraulic oil temperature rise is too high (generally less than 60 ℃), resulting in a decrease in viscosity and an increase in the internal leakage of the cylinder.
C. Reasons for the oil cylinder itself
The main reason for this is processing or secondary processing. Due to poor processing quality, the processing accuracy deviation is caused, resulting in rough cylinder walls, damaged seals, and oil leakage under high pressure.
2.2 Handling measures
A. Oil cylinder leakage
① The selection of oil cylinder cups, skeleton oil seals, etc. should be appropriate, and check for aging before installation; ② Before installing the seal, check for burrs at the contact area and ensure that the smoothness meets the installation requirements.
B. Oil cylinder crawling
① During the operation of the bucket wheel machine, it is necessary to exhaust the cylinder at an appropriate time. Before adjusting the exhaust device, the working pressure inside the cylinder should be reduced to around (0.5-1) Mpa. It is strictly prohibited to? Under normal working pressure, perform exhaust operation. When the push rod reaches the end of the stroke and the pressure rises, open the exhaust plug immediately. Before starting to return, close it immediately. After spraying white turbid foam like oil, exhaust the air completely. ② The tightness of the sealing ring at the end cover of the hydraulic cylinder should be just right, neither too loose nor too tight. ③ Corrosion and scratching inside the cylinder: For the phenomenon of corrosion and scratching inside the cylinder, boring and grinding or re chrome plating should be carried out.
3. Analysis and Treatment of Common Causes of Throttle Valves
Bucket wheel machine? The use of Z2FS16-20 throttle valve in the pressure system mainly achieves the purpose of adjusting the pitch and rotation speed by adjusting the throttle port and changing the flow rate.
3.1 Fault phenomenon and cause analysis of throttle valve
① Throttle valve malfunction or limited adjustment range. ② The movement speed is unstable. Unstable movement speed mainly refers to the phenomenon of gradually slowing down, suddenly increasing, or jumping during the movement of the throttle valve. The main reasons for the above phenomena are: 1) Impurities accumulate or adhere to the edge of the throttle port, reducing the flow cross-section and causing a decrease in flow rate per unit time, resulting in a slowdown of the actuator speed. 2) Due to vibration, the throttle port changes, resulting in poor throttling performance. 3) The throttle valve is leaking. 4) There is a large amount of air in the system, forming a mixed flow of oil and gas, resulting in intermittent oil flow, discontinuous and unbalanced throttle valve flow, and causing the actuator to not operate smoothly. ③ Due to personal reasons. Leakage caused by inadequate installation or manufacturing accuracy, large gap between valve core and hole, damaged sealing components of throttle valve, blockage of throttle port or jamming of valve core leading to adjustment failure. ④ External factors. 1) The bucket wheel pump room has few insulation measures, and the temperature is prone to accumulate, leading to excessive temperature rise in the system. 2) Air or impurities entering the oil can cause the slide valve to jam, become rough, and block the oil circuit. 3) The vibration of the bucket wheel machine causes the throttle valve adjustment value to drift.
3.2 Handling measures
Unstable movement speed: ① In response to this situation, it is necessary to add a throttle locking device to avoid sudden changes in system flow caused by vibration. ② The throttle valve is leaking internally. After disassembling the throttle valve, it is necessary to check the accuracy and fit clearance, and promptly correct or replace any parts that exceed the tolerance. ③ Heat dissipation devices can be added to reduce the temperature of the system oil.
4. Analysis and Treatment of Common Malfunctions of Balance Valve and Explosion proof Valve
The balance valve model of the bucket wheel hydraulic system is ZNS-AB02-5-S0-D1. Improper adjustment of the balance valve opening can cause unstable and uneven pitch speed, either fast or slow, and even shaking of the cantilever. Long term use can cause damage to the proportional amplification card of the control proportional reversing valve, leading to the system stopping working. Therefore, it is necessary to debug it properly; The explosion-proof valve model is FQGA-XAN-1CX (90LPM). The explosion-proof valve is mainly used to prevent sudden pipeline rupture and system accidents, but it can also have negative effects. For example, when the bucket wheel machine is taking coal from the track, the flow rate cannot be too large, and the bucket teeth cannot gnaw on the ground. Otherwise, the load will be very large, and the collapse of the coal pile will be more serious. When the system flow rate increases rapidly, the explosion-proof valve will mistakenly think that the pipeline has exploded and lock up, resulting in the inability to establish back pressure and work normally.
5. Conclusion
In short, when troubleshooting the hydraulic system of the bucket wheel machine, it is necessary to combine reality, analyze and demonstrate in detail the causes of this fault, so as to propose more accurate solutions.
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2025-10-31