Analysis and Research on Common Faults of Loader Hydraulic System

With the continuous development of modern society, some advanced scientific and technological advancements have been introduced into engineering construction, leading to an increasing speed of development in construction machinery. One of the commonly used equipment in construction machinery is the engineering loader, which is powered by a hydraulic system during operation. However, during use, the hydraulic system of the engineering loader is inevitably prone to some malfunctions, which hinder the safe operation of the loader and bring many inconveniences to engineering construction. The paper analyzes and studies common faults in the hydraulic system of loaders, hoping to be helpful to relevant personnel.

【 Keywords 】 Loader; Hydraulic system; Fault; analysis

1. Introduction

In the process of the development of construction machinery, there is maintenance of construction machinery, which plays an important role and position. Construction machinery maintenance refers to the maintenance of mechanical equipment, the restoration of the usability of construction machinery, and the use of effective maintenance techniques to reduce equipment failure hazards and extend the service life of equipment. This article analyzes the hydraulic system faults of loaders in construction machinery equipment based on this concept, and explores specific solutions to the faults. This has certain research value and significance for the development of China's construction machinery maintenance industry.

2. Hydraulic system of engineering loader

Engineering loader is a self-propelled construction machinery, which mainly operates in the following ways: loading, shoveling, transporting, unloading, traction and scraping. The hydraulic system of the engineering loader is the main power source of the loader. By controlling the loader through the hydraulic system, the operation of the loader can be achieved. Once the hydraulic system of the loader malfunctions, it will cause problems with the overall performance of the hydraulic system, thereby affecting the normal operation of the loader and causing serious losses to engineering production. The hydraulic system mainly includes hydraulic oil tank, hydraulic pump, hydraulic oil, hydraulic valve, hydraulic oil pipe, hydraulic cylinder, piston, and various hydraulic oil filter elements.

3. Analysis of common faults in the hydraulic system of loaders

3.1 Loader bucket falling and floating fault

The common faults during the operation of engineering loaders are bucket dropping and floating, mainly manifested as: although the boom can work normally, the bucket and rotor are powerless, which makes the loader unable to operate well. In response to this phenomenon, maintenance personnel conducted a detailed analysis and found that according to the manifestation of the fault, the faulty part in the hydraulic system of the loader should be the bucket cylinder or some operating system issues. That is to say, the cause of this malfunction is the hydraulic system experiencing pressure relief. Therefore, maintenance personnel need to carry out damage investigation on the components of the hydraulic system, find the damaged parts, and thus identify the cause of the malfunction. The specific maintenance process for the above-mentioned faults is as follows: firstly, the maintenance personnel need to check the piston of the rotary bucket cylinder in the hydraulic system, with a focus on the sealing of the valve, and check whether the entire chamber of the oil cylinder is in a connected state; Secondly, maintenance personnel need to check whether the oil seal of the rotary bucket cylinder is damaged and whether its specific size does not match the actual requirements. Once it is found, it needs to be replaced immediately; Once again, check the pipeline of the rotary bucket cylinder. If any damage or insufficient sealing is found, replace it immediately; After Z, maintenance personnel need to inspect the control valve of the rotary bucket cylinder, mainly to check its fit clearance, and do not exceed the specified range. Once exceeded, replace it immediately.

3.2 The loader has a "nodding" phenomenon when lifting the boom

During the operation of the loader, there may be a phenomenon of the boom nodding during the lifting process. Maintenance personnel analyzed this phenomenon and found that it may be caused by the backflow trend of the pressure oil in the large chamber. The reason for the reverse flow trend of the pressure oil in the large chamber is that in the working device of the transfer machine, the distribution valve generally adopts a positive opening and negative closure structure. When reversing, there may be a short-term communication between the inlet and the working oil port, which will cause the pressure of the hydraulic system to instantly decrease. Once the mass inside the boom is large, it will cause residual pressure in the large chamber of the boom cylinder, thereby forming a trend of reverse flow of pressure oil in the large chamber. The trend of oil backflow in the large chamber pressure causes the boom to descend and then ascend, resulting in a "nodding" phenomenon. Therefore, during the maintenance process, maintenance personnel should focus on checking the distribution valve of the loader hydraulic system. Once there is a "poor sealing" phenomenon, it should be replaced.

3.3 The boom of the loader descends and experiences intermittent phenomena

During the operation of the engineering loader, there may also be a phenomenon of the loader arm descending, accompanied by intermittent faults, resulting in severe shaking of the entire equipment, and in severe cases, slow lifting of the arm. During the troubleshooting process, the maintenance personnel first checked whether the hydraulic pump had malfunctioned. After ruling out the hydraulic pump malfunction, they checked whether the pilot system pressure met the regulations and whether the operator operated according to the regulations. After eliminating the above faults, the maintenance personnel can place the fault inspection on the lifting cylinder and lifting slide valve. The main purpose is to check whether the valve core is stuck. If it is, a new valve core needs to be replaced. In addition, it is necessary to check whether there is balance in the two chambers of the hydraulic cylinder. If there is balance, it may cause the boom to continue to descend, resulting in severe shaking of the loader. In this case, maintenance personnel need to replace the lifting slide valve.

3.4 Failure to lift the boom effectively

During the actual operation of the loader, sometimes there may be a malfunction where the boom is unable to lift, and the bucket can still work normally. The maintenance personnel analyzed the causes of the fault and found that there are two forms of this fault, namely: first, the boom is unable to lift and the bucket cannot fall off; The second issue is the inability to flip the bucket and lift the boom. And for different forms of faults, the maintenance strategies are also different, which requires maintenance personnel to carefully analyze and inspect. After analyzing the causes of the malfunction, we conclude that when various forms of malfunctions occur, it indicates that the cause of the malfunction should be on the work distribution valve or the piston of the boom cylinder, and these two parts need to be carefully inspected; When the form of the fault is the second situation, it indicates that the cause of the fault should be in the gear pump or working valve, and maintenance personnel need to focus on this inspection. To identify the cause of the malfunction, it is necessary to carry out critical maintenance work on the specific parts. Once damage or insufficient sealing is found in the components, it is necessary to replace them with new ones in a timely manner to ensure good sealing and extend the service life of the equipment.

4. Maintenance and upkeep of hydraulic system for engineering loaders

Engineering loaders, like other mechanical equipment, require daily maintenance work. For the use of new equipment, it is necessary to check its running condition, accurately understand the operation of the equipment, and avoid the problem of equipment failure as soon as it is put into use. After using the equipment for a period of time, a key inspection should be conducted on its quality condition, checking whether the screws and other small components are installed properly according to regulations, whether there are any abnormal oil temperatures, whether the oil is contaminated, etc. In short, it is necessary to meet the operating conditions of the equipment. For equipment that has been in use for a long time, it is necessary to focus on inspecting its pipelines and instruments, and checking the fastening devices of the equipment to ensure that it is in good working condition.

5. Analysis of common fault diagnosis methods for hydraulic systems of engineering loaders

5.1 Inspection of Hydraulic Oil Tank Condition

When inspecting hydraulic oil, it is important to pay close attention to the hydraulic oil tank. When inspecting the hydraulic oil tank, maintenance personnel should pay close attention to whether there is any blockage or insufficient sealing. Once the above situations occur, it needs to be replaced in a timely manner.

5.2 Inspection of suction pipe condition

Once the oil suction pipe leaks, the fault will be very obvious. Therefore, when inspecting the fault, maintenance personnel will use the method of checking the status of the oil suction pipe according to the type of fault to determine the cause of the fault. It should be noted that damaged suction pipes must be replaced.

5.3 Inspection of Hydraulic Pump Wear Condition

The wear and tear of hydraulic pumps is an important cause of loader failure or decreased work efficiency. Therefore, when inspecting faults, maintenance personnel can start with the wear and tear of hydraulic pumps based on specific situations.

5.4 Check if the sealing ring of the boom cylinder is damaged

In general, when the boom malfunctions, it is mostly caused by damage to the sealing ring. In order to save maintenance time, maintenance personnel need to start inspecting the sealing ring and replace it immediately once it is damaged.

6. Conclusion

In short, in the process of analyzing faults in the hydraulic system of engineering loaders, each inspection step must be subdivided, and the purpose of each inspection step must be clear, gradually extending from easy to difficult, starting from key points. Eventually, the cause of the fault will be identified and effective solutions will be taken. Only in this way can we save time on troubleshooting, improve the service life of equipment, and create more value.

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