Fourteen common problems of construction machinery maintenance
The correct means of maintenance and good maintenance skills will greatly extend the service life of construction machinery, the following construction machinery home Xiaobian to explain to you about the construction machinery maintenance knowledge.
1, can not correctly judge the fault analysis, blind dismounting phenomenon It is quite common for
Some maintenance personnel due to the unclear on the structure and principle of engineering machinery, without a careful analysis of the fault reason, can not accurately determine the fault position, with "probably, almost" blind thought of mechanical dismounting, not only the results of the original fault has not ruled out, but due to poor maintenance skills and technology, and the emergence of new problems. Therefore, when the mechanical failure, should be tested by testing equipment, such as testing equipment, through the fault diagnosis methods and means, check, test, ask to see "the tradition, combined with the structure and working principle of engineering machinery, to determine the most likely failure of the site. In determining the fault of construction machinery, the commonly used "exclusion" and "comparison method", follow from simple to complex, first appearance after the first assembly and parts, internal order, avoid "without forethought, blind dismounting".
2, do not check for new quality, common failure problems after assembly
Before the replacement of parts, some maintenance personnel do not do the technical inspection of the new accessories, and directly installed to the construction machinery, this approach is unscientific. Spare parts currently on the market are not bad quality, some fake fish and some accessories; accessories inventory for too long, the performance changes, without detection, often caused by failure after assembly. Before the replacement of new accessories, the necessary inspection test must be carried out, including the appearance and performance testing, to ensure that the new fittings without fault, to prevent unnecessary trouble caused by it.
3, do not pay attention to substitute or misuse of accessories accessories models, the more common phenomenon
In the maintenance of mechanical parts, substitute or misuse of the phenomenon still more common, some parts of emergency replacement is feasible, but long time use is harmful to safety and technical performance of machinery. Some maintenance personnel on mechanical structure, principle of understanding less, many parts and components model does not match, but think that as long as you can install on the line, do not consider whether to play the mechanical performance of the machine. Therefore, in the maintenance of engineering machinery, should try to use the original types of accessories, not available in other types of accessories substitute, but not misuse.
4, do not pay attention to the selection of bolt, bolt use chaotic phenomenon is more prominent
In the maintenance of construction machinery, the phenomenon of indiscriminate use of bolts is still relatively prominent, because the bolt performance, quality does not meet the technical requirements, resulting in frequent mechanical failures after maintenance. The special bolts used in mechanical engineering, such as shaft bolt, cylinder head bolt, connecting rod, flywheel bolts, injector fixing bolt is made of special materials through special processing is made, its strength, shear strength, ensure connection, reliable fixation. The actual maintenance operation, some maintenance personnel found that the bolt is damaged or missing, can not find a standard bolt, take some random bolts to replace some other, making their own alternative, these bolts due to poor material or process failure for later engineering machinery to leave hidden faults. Some parts of a "small pitch" and "thin buckle self tightening bolt, bolt," copper copper bolt, but the use of ordinary bolt instead, resulting in self bolt loose, difficult disassembly phenomenon; some bolts after use will appear after tensile deformation and other defects, some technical requirements and must be replaced several bolts after, because maintenance personnel do not understand the situation, repeated use of the bolt is not qualified, is also prone to cause mechanical failure or accident. Therefore, in the maintenance of construction machinery, when the bolts damaged or lost, timely replacement of the required bolts, must not use bolts.
5, a "blind replacement parts, replacement and repair" phenomenon exist in different degrees
Troubleshooting and mechanical engineering judgment is relatively difficult, some maintenance personnel with a consistent method of test, no matter large small pieces, as long as that may be the cause of the fault components, a replacement test, the result not only failure is not ruled out, and the replacement of parts replaced, an increase in consumer spending. Some parts can be repaired to restore fault through its technical properties, does not require complicated repair technology can repair, but the maintenance staff but requires the user to replace the new thing, just take the method of "replacement and repair", causing serious waste. The blind replacement test and the blindly replacement of repairable parts also exist in some repair units to varying degrees. In maintenance, we should carefully analyze and judge the cause and location of the fault according to the fault phenomenon, repair the parts that can be repaired, restore the technical performance, and eliminate the blind replacement of parts and components.
6, the use of the gasket is not standardized, free use of the phenomenon still exists
Engineering machinery parts with the surface of a lot of use of the washer, commonly used with asbestos pad, rubber pad, paper pad, cork mat, felt pad, pad of non-ferrous metals (copper, aluminum, copper pad pad) skin (steel) asbestos pad, insulation pad, spring washer, flat pad etc.. Some of them are used to prevent oil leakage, leakage, leakage and leakage between parts, and some of them are fastening and anti loosening. Each type of gasket used occasions have different regulations and requirements, in the maintenance of engineering machinery, gasket even non-standard use of indiscriminate use of the phenomenon is relatively serious, resulting in leakage often happen with the surface, bolt and nut to loosen, loosen, affect the normal use of Engineering machinery. If the engine cylinder gasket is too thick, the compression ratio decreases, difficulty in starting the engine; injector and cylinder head with copper gasket surface, such as the use of asbestos pad instead, easy to make the injector cooling bad ablation; between the combined surface of the gasket is too thick oil pump and fuel injection pump diesel oil, resulting in insufficient oil quantity and oil pressure diesel engine, power down; such as leakage spring loaded locking pad, pad, gasket, the joint is not tight, loose or leakage happens easily; for middle hole gasket and forget opening lead to channel oil road, the engine block, burnt axle, water boiling phenomenon also occurs frequently. Remind the maintenance personnel maintenance engineering machinery, remember "small useful gasket".
7, improper bolt tightening method is serious
All parts of engineering machinery fixed or most bolt tightening torque requirements, such as injector fixing bolt, cylinder head bolt, connecting rod, flywheel bolts, some provisions of the tightening torque, some provisions of the tightening angle, but also provides a tightening sequence. Some maintenance personnel, who will do that to tighten the bolts of no great importance, not according to the provisions of torque, and tighten the order (some do not understand the required tightening torque and sequence), do not use a torque wrench (kg), or feel free to use the afterburnerrod resulting in tightening, tightening torque difference. The torque is insufficient, easy to loose bolts, which leads to bad cylinder liner, bearing looseness and leakage and leakage; the torque is too large, easy to bolt tensile deformation and fracture, sometimes damaged screw hole, affect the quality of repair. Therefore, in the maintenance of construction machinery, must tighten the bolts according to the prescribed torque and order, to prevent bolt tightening torque is too large, too small or improper order and lead to mechanical failure.
8, do not pay attention to the parts with the gap detection number
The diesel engine piston, piston ring and cylinder with the gap of "three gap", the piston top clearance, valve clearance, piston clearance, brake shoe clearance, the driven gear meshing clearance, bearing axial and radial clearance, valve rod and valve guide clearance, various models have strict requirements, at maintenance must be to measure, do not meet the clearance requirements of parts to be adjusted or replaced. The actual maintenance work, do not measure the clearance and blind assembly parts the phenomenon of a large number, resulting in early bearing wear or erosion, burning oil, diesel engine is difficult to start or deflagration, piston ring broken, mechanical impact, oil spills, leakage and other faults, sometimes due to improper parts with the gap, causing serious damage accident mechanical.
9, unpaired, complete replacement parts or components are not uncommon
There are a lot of engineering machinery parts, such as plunger fuel system of diesel engine, an oil outlet valve side, fuel injector side pair; drive axle main reducer drive gear and the driven gear device; hydraulic control valve in the valve block and valve; hydraulic steering gear of the valve core and the valve sleeve, the with couples in the factory manufactured by special processing and grinding, paired with a very precise and, in the lifetime of use has always been used in pairs, not interchangeable with each other; some components, such as the piston and the cylinder, bearing and shaft neck, valve and valve seat, the connecting rod and the rod body cover tile. After a period of running, with relatively good in maintenance, should also pay attention to pair assembly, don't get on; diesel engine connecting rod, piston, fan belt, high-pressure oil pipe, oil seal, bulldozer excavator main central rotary joint Clutch tape Festival, the machine also uses a set of accessories, damaged must complete replacement, or because the parts quality difference, recency, length of different sizes, will lead to unstable operation of diesel engine, hydraulic system leakage, load concentration phenomenon is serious, easy replacement of parts of early damage etc.. In the actual maintenance work, some people in order to reduce costs, some people do not understand the technical requirements, not in pairs or complete replacement parts of the above is not uncommon, reduces the engineering machinery maintenance quality, shorten the life of parts, increase the possibility of failure, should cause enough attention.
10, maintenance taboo forgets, hidden failures are frequent
Maintenance of construction machinery, some maintenance personnel do not understand the maintenance should pay attention to some of the problems, resulting in disassembly often occur "habitual" errors, affecting the quality of mechanical maintenance. Such as when disassembling the engine cylinder cover, cylinder head deformation caused cracks; the installation of piston pin and piston, without heating directly to the piston pin into the pin hole, causing the piston deformation increases ovality increase; crankshaft main bearing connecting rod or back with copper pad or pad of paper, easy to plug the oil, resulting in burning tile holding in the maintenance of diesel engine shaft accident; excessive scraping bearing, the bearing surface of the antifriction alloy layer was scraped, resulting in bearing steel back and crankshaft friction wear early; remove bearing, pulley does not fit the use of machines parts, hard hit hard knock, easily lead to deformation or damage of parts; opening new piston and the cylinder, nozzle, plunger and other parts, parts of the surface with fire sealed oil or wax, to change the performance of the parts are not conducive to the use of spare parts.
11, when assembling parts loaded against the situation have occurred
In the maintenance of construction machinery, some parts assembly has strict direction requirements, only the correct installation, to ensure the normal work of components. Some parts of the external features are not obvious, both positive and negative can be installed, often in the actual work of the installation of the reverse, leading to early damage of parts, machinery can not work properly, construction machinery damage accidents. Such as engine cylinder liner, with variable pitch valve spring (F6L912 diesel) engine, piston, piston ring, fan blades, gear pump side plate, seal, thrust washer, thrust bearing, thrust washer, oil retaining ring, injection pump, clutch disc hub, drive shaft universal joint, the the parts in the installation, such as do not understand the structure and installation considerations, most anti transvestite, resulting in the assembly is not working properly, cause malfunction of Engineering machinery. Therefore, the maintenance personnel in assembly parts, must grasp the structure and installation requirements of parts, not for blind installation.
12, the maintenance method is not formal, "palliative" is still some of the usual means of maintenance units
In the maintenance of construction machinery, some maintenance personnel do not take the correct maintenance methods, that the emergency measures are omnipotent, to "emergency" instead of "repair", "temporary cure" phenomenon is still a lot. For example, "welding repair instead of repair" is an example, some components can be repaired, but some maintenance personnel save trouble, but often use "welding dead" method. Hydraulic cylinder piston rod thread earrings and damaged, with direct welding method, which can not be replaced after damaged cylinder seal, serious oil leakage; when the device moves slowly or to difficulties, do not check the cause of the malfunction, blindly high system working pressure, cause the system pressure is too high, easy to damage, pipeline, oil seal hydraulic components; in order to make the diesel engine "is strong", large artificially adjusted fuel injection pump oil and high pressure injector. These irregular maintenance methods can only be emergency, but can not be used for a long time, we must fundamentally find out the causes of failure, take regular maintenance methods to troubleshoot, should cause the attention of maintenance personnel.
13, "small" is not paying attention, because "small" missing "" cause the fault increases
In the maintenance operation, some maintenance personnel often only pay attention to the fuel pump, oil pump, piston, cylinder liner, piston ring, hydraulic pump, control valve maintenance, braking and steering system and other parts, but ignored the filter, relief valve, all kinds of instruments such as "small" maintenance, they think that these "small" the influence of mechanical work, even if the damage is of no great importance, as long as mechanical work is to do with, but it is these "small" lack of maintenance, lead to premature wear, shorten the service life. Such as the use of construction machinery diesel filter, oil filter, air filter, hydraulic oil filter, water temperature, oil temperature and oil pressure, sensor, sensor, alarm, preheating plug, oil filter, water tank cover, tank cap, oil filler cap, grease reservoir pump sewage switch, battery box, fuel injection for oil return connector, pin, fan cover, shaft bolt lock piece, these "small" is the normal work of engineering machinery and maintenance of service life is essential, prolonged mechanical, maintenance operations, such as not pay attention to maintenance, often runs the risk, cause malfunction of engineering machinery the.
The 14 part, decontamination, cleaning is not thorough, early damage, corrosion often occurs
Maintenance of construction machinery, the correct removal of parts of the surface oil, impurities, to improve the quality of repair and prolong the service life of the machine is of great significance. Due to not pay attention to strengthen the cleaning of parts, cleaning agent selection unreasonable, improper cleaning methods, leading to early wear and corrosion damage of parts, in some repair units also occur. If not completely remove the cylinder steps, coke in the piston ring groove, bolt holes in the debris, hydraulic components in the sand, resulting in insufficient torque bolt, piston ring easily broken, cylinder pad ablation, hydraulic components early wear. In the overhaul of engineering machinery, do not pay attention to remove diesel filter, oil filter, hydraulic oil filter, diesel engine water jacket and the radiator surface, lubricating oil etc at the accumulation of oil or impurities, so that the maintenance work is not complete, reduce mechanical failure free operation time. Repair personnel in the cleaning of parts, a correct choice of cleaning agent. For various parts cleaning, according to their different requirements for cleanliness, correctly choose different cleaning agents; two, to prevent corrosion and rust of parts. In order to ensure the quality of parts, parts corrosion and rust should be prevented, especially for the precision parts, no corrosion or rust to any extent. So when washing is not available, alkaline cleaning agent (especially alkaline cleaning agent cleaning) Aluminum Alloy parts (such as Aluminum Alloy cylinder head), but not with strong acid cleaning agent for copper parts (such as thermostat main valve), in order to minimize mechanical corrosion; third is different parts classification of cleaning. Aluminum Alloy parts, copper parts should not be in acidic or alkaline cleaning agent in a cleaning, rubber parts and other steel parts should not be put in the gasoline and diesel oil and acid and alkaline cleaning agent to clean together.
If we can effectively avoid the above problems in the construction machinery failure, we can speed up the maintenance speed, save time and improve work efficiency.
