Engineering machinery and equipment common problems and maintenance - Solutions - Huaqiang Electronic Network

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China's engineering machinery repairs are carried out in general repair shops, and there are very few targeted personnel repairs; there are many different maintenance problems in the maintenance of engineering machinery. Some mechanical understanding and understanding, a simple analysis of some problems of engineering machinery, pointing out the causes and consequences of maintenance, and avoiding problems. The maintenance definition of construction machinery is the most direct technical means to extend the service life and service life of construction machinery by restoring the use of construction machinery by personnel to repair and reduce the hidden troubles of construction machinery through technical means. After decades of development in various fields, our country has developed to a certain scale. There are also many professional technical schools for maintenance. However, due to the relatively late rise of the construction machinery maintenance industry in China, the maintenance of construction machinery and There are many insurmountable problems in technical support, and many technical problems have not yet been solved. This paper puts forward the viewpoint of the maintenance problems of the existing engineering machinery in our country, analyzes the incorrect mechanical repair operation in the maintenance process, hopes to carry out technical exchanges with everyone, and contributes to the maintenance of engineering machinery in China. mutual encouragement. Maintenance personnel have insufficient ability to analyze faults and blindly perform mechanical disassembly during maintenance, as some maintenance personnel are unclear about the mechanical structure and mechanical repair principles. I did not seriously analyze the cause of the failure. I did not find the most accurate part of the mechanical failure. Based on the previous "probably, maybe" work idea, there was no purposeful dismantling of the machine. The mechanical failure has not been eliminated and repaired. On the contrary, in the rough disassembly process, due to the immature maintenance technology and poor process, the machine has experienced new failures. In the working environment, the author came into contact with a Doosan bulldozer. The original fault was caused by the power of the diesel engine of the bulldozer, which caused the machine to work normally during the work, and the maintenance personnel used the idea of ​​the old work to carry out the machine. Disassembly, if the PT fuel injection pump and the injector are disassembled and disassembled, the cause of the failure is not found out, and one injection pump test is replaced at will, and the fault remains. The reason for the final inspection failure is that the diesel internal impurities and moisture are caused by the excessive disassembly of the diesel fuel pump. Through the testing equipment, the first inspection is carried out. If the equipment is not adhered to, the technical guidance of the old maintenance personnel or the maintenance personnel can be used for technical discussion. Do not blindly perform mechanical disassembly, and must be combined with the structural drawings and working principles of the engineering machinery. Fault location. The fault location is determined. Generally, the “exclusion method” and the “comparative method” are used to comply with the simple and responsible, first and then the inner table, and the first assembly is repaired in the order of the parts. If you don't pay attention to checking the quality of new parts, the parts and machinery will not work after assembly. When replacing mechanical parts, standard and technical inspections of new mechanical parts are usually carried out, but some maintenance personnel are at this point. It is often more careless, and it is very unscientific to do any technical inspection of the new parts department that is used. This method is very unscientific. At present, the quality of spare parts in China's machinery market is uneven. The accessories of the various Chinese cottages are endless. Some accessories are also too long due to long inventory time, and the performance is greatly reduced. If it is not tested by technology, it will often cause trouble after assembly. 1 Shanghai 120A bulldozer, due to the freezing crack of the diesel engine oil cooler, causing water in the oil, replacing the new oil cooler, starting the test machine, the oil is still in the water, the maintenance personnel have carried out other parts of the inspection, both Did not find out the cause of the failure. Later, the maintenance personnel opened the side cover of the new oil cooler and found that the oil seal ring at the side cover was not compacted, which caused the oil and water to mix. The cause of the mechanical failure was that the quality of the oil cooler was not good. One ZL50 loader, the engine oil pressure of the diesel engine is too low, the analysis is that the oil filter is clogged, the new oil filter is replaced, and the test machine oil pressure has not been improved. After inspection or replacement of all parts that may cause low oil pressure, but the oil pressure can not be raised, and finally barely used in the case of failure to find the cause of the failure, low oil pressure, resulting in diesel engine burning shaft, crankshaft The fracture and the connecting rod are bent, and the loss is more than 10,000 yuan. Later, after the work of the maintenance technician, the cause of the mechanical failure was that the replaced oil filter element (strainer) had been blocked by excessive rust, because the filter parts were leaking due to long-term inventory storage. Contact with the environment in the air causes internal rust. Therefore, the maintenance personnel must carry out the technical inspection of the parts before pre-installing the new parts of the machinery. It is very necessary to check the technical inspection. The inspection includes the appearance and performance test to ensure that the new parts are not faulty and prevent unnecessary troubles caused by them. Bolt tightening methods have occurred in the use of construction machinery. The fixing or connecting bolts of various parts of the construction machinery have tightening torque requirements, such as injector fixing bolts, cylinder head bolts, connecting rod bolts, flywheel bolts, etc. Tightening torque, some specifies the tightening angle, and also specifies the tightening sequence. However, some maintenance personnel in the work only think that the link is considered to be unskilled, and whoever thinks that it is the same, irrelevant, does not tighten in the assembly machinery according to the specified torque and order, does not use a torque wrench, or Feel free to use other force rods and tighten them only by your own feelings, resulting in a large difference in tightening torque. If the bolt torque is insufficient, it will be easy to loosen, which will cause the cylinder liner to be damaged, the bearing bush to loosen, oil leakage and air leakage; the bolt torque is too large, the bolt is easy to be stretched and deformed, and even breaks. Damage to the threaded holes increases the difficulty of repairing. For example, a ZL50 loader, the torque converter slams the hydraulic oil. The reason caused by the technician and careful inspection is that the bolts in the coupling pump wheel and the cover wheel are not tightened in the specified order. Therefore, the vast number of engineering machinery maintenance personnel must be in accordance with the specified torque and bolt tightening technical requirements when repairing machinery, a little sloppy. Do not pay attention to the selection of bolts, the phenomenon of chaotic use of bolts is more prominent in the process of engineering machinery maintenance, there is also a point that the majority of maintenance personnel need to pay attention to, that is, the use of bolts, in the daily mechanical maintenance due to bolt performance, quality Cases that do not meet technical requirements and cause mechanical failure after repairs occur from time to time. The bolts used in construction machinery are all special. (Source: http://) Each part has specific bolts for installation. The design requirements and quality of bolts in different parts are also different. of. For example, the bolts of the drive shaft, the bolts of the cylinder head, the bolts of the connecting rod, the bolts of the flywheel, the fixing bolts of the injector, etc. are all made of special materials or synthetic materials through special machining, and the strength is strong and resistant. Strong shearing force ensures reliable connection and fixing. In the actual maintenance and maintenance of construction machinery, most maintenance personnel find that when these bolts are damaged or missing, and because the time is too tight to find the standard bolts, they can take the bolts of other mechanical parts instead of installing them. It is not required to directly replace the self-processing machinery. It is not known that the bolts of these quality parts are poorly graded or the processing technology is unqualified, and there are great troubles in the use of construction machinery. Neglecting the phenomenon of detecting parts and clearances. The power of engineering machinery is diesel engine, and the piston and cylinder sleeve of the diesel engine cooperate with the gap, the piston ring "three gaps", the piston head clearance, the valve clearance, the plunger clearance, the brake shoe clearance, the main Driven gear meshing clearance, bearing axial and radial clearance, valve stem and valve guide clearance, etc., the clearance between these specific accessories is required by technical parameters, the various accessories in different construction machinery The requirements are all different. Therefore, mechanical maintenance technicians must make measurements when performing mechanical maintenance. For those gaps between accessories that do not meet the requirements, it is necessary to re-adjust the conditions. If the parts are not matched, the parts are replaced because the installation is not in place. Must be reinstalled. Don't be signed for fear of trouble.

During the 12th Five-Year Plan period, the state vigorously develops basic construction projects. The use of machinery is of vital importance. In order to ensure the development of a harmonious society, the use rate of construction machinery must be guaranteed. The most effective method is to cultivate a large number of high-tech engineering technologies. Maintenance staff.