Hefei Shuoyuan Engineering Machinery Parts Co., Ltd.

Common problem

When engineering machinery maintenance, what can not be done!

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Repair is the skill and function of rehabilitation engineering machinery. It eliminates problems and eliminates the risk of illnesses. It is an effective way to extend the life span of machinery.

At that time, the domestic auto repair profession had a considerable scale, and the construction machinery repair profession started relatively late. There are still many skills problems in the repair. The existence of these problems has led to the low quality of mechanical repairs and poor reliability of equipment, which has caused consumers to suffer losses and even severe attacks on construction machinery. The author briefly analyzes the common skill problems encountered in the repair of construction machinery, aiming to arouse the attention of relevant personnel.

Do you have committed these faults during the repair of construction machinery?

One, can not correctly identify the problems, blindly dismantling and unloading phenomenon is accustomed to

Some repair personnel are not clear about the structure and principles of the construction machinery. They do not carefully analyze the cause of the problem, and cannot accurately determine the location of the problem. They blindly disassembled the machine with the idea of “about the same,” and the result was not only that the original problem was not cleared, and Because of poor repair skills and craftsmanship, new problems have emerged.

Therefore, when the machinery is faulty, it is necessary to conduct inspections through testing equipment. If there is no detection equipment, it is possible to determine the traditional fault diagnosis methods and methods, such as “ask, look, check, and test”, combined with the structure and operation principle of the construction machinery. The most likely part of the attack. When judging defects in construction machinery, it is common to use the “sweep method” and “comparison method” in accordance with the sequence from abbreviated to clutter, first appearance after interior, first assembly and then component, avoid “do not ask indiscriminately, blindly dismantle ".

Second, do not check the quality of new parts, the problem of the device is more common

Before replacing the accessories, some repair personnel did not do a skill check on the new accessories and used it directly on the construction machinery. This is unscientific. The parts and components sold on the market today are of unequal quality, and some counterfeit and shoddy accessories are indiscriminate; there are also a few parts that are subject to changes in the onset of inventory because of too long an inventory. If not detected, devices often cause problems.

Therefore, before the replacement of new accessories must carry out the necessary examinations, testing, including appearance and function tests, to ensure that the new parts are free of defects, to eliminate unnecessary trouble caused by it.

Third, do not pay attention to the type of accessories, replacement or misuse of accessories more than the phenomenon

When repairing construction machinery, the phenomenon of replacement or misuse of spare parts is still more widespread, and some accessories are feasible for emergency replacement, but long-term use is harmful and unsafe, affecting the safety and skill functions of the machinery. Some repair personnel have little knowledge of the mechanical structure and principles. Many types of spare parts do not match, but they think that they can only be installed and do not consider whether they can use the mechanical skills. Therefore, when repairing construction machinery, original types of accessories should be used as much as possible, and other types of accessories should not be used instead, and they should not be misused.

Fourth, there are a number of phenomena that do not pay attention to detecting the cooperation gap between parts and components.

Diesel engine piston and cylinder sleeve cooperation gap, piston ring "three gaps", piston head clearance, valve clearance, plunger clearance, brake shoe gap, master driven gear meshing gap, bearing axial and radial clearance, valve stem With the cooperation of valve guides and other gaps, all types of aircraft have strict requirements. It is necessary to carry out measurements when repairing, and to adjust or replace parts that do not meet the requirements of clearance. In practice repair operations, there are a number of blind device components that do not measure the cooperation gap, resulting in premature wear or ablation of bearings, diesel engine oil burning, difficulty in starting or detonation, breakage of piston rings, mechanical impact, oil leakage, and air leakage. Such problems, sometimes even due to the improper cooperation of parts and components, lead to serious damage to the event.

V. It is not uncommon for unpaired, complete sets of replacement parts or components

There are many parts on the construction machinery, such as the pump pump/distributor plate of the hydraulic pump, the plunger pair of the diesel engine fuel system, the outlet valve, and the nozzle coupler; the master and slave in the drive reducer main reducer Actuated gears; valve blocks and valve stems in hydraulically actuated valves; valve plugs and valve sleeves in full hydraulic steering gears; these partnerships are manufactured through special machining in a factory, paired with grinding, and the cooperation is very delicate. The life cycle used has been used in pairs and must not be exchanged; some mutual cooperation components such as pistons and cylinder liners, bushings and journals, valve and valve seats, connecting rods and caps, etc., have passed through a period of time. The use of running-in, relatively good cooperation, in the repair, should also pay attention to the paired device, do not get string; diesel engine connecting rod, piston, fan belt, high pressure tubing, excavator central reversible joint oil seal, hydraulic pump and hydraulic motor plunger And so on, these one machine use a set of accessories together, and the damage must be completely replaced. Otherwise, due to the different quality of the accessories, different old and new, different lengths and sizes, it will lead to unstable diesel engine operation and hydraulic pressure. Department of unstable oil spills, easy to replace parts damaged early. In the practice of repairs, it is not uncommon for an individual to replace the above-mentioned components in order to reduce expenses and some people do not understand the skill requirements. This has reduced the quality of repair of construction machinery, shortened the life of components, and increased the number of defects. The possibilities should cause attention to satisfaction.

Sixth, "small pieces" do not pay attention to good or bad, because "small" lost "large" cause problems add

During repair work, some repair personnel only focus on the protection of spare parts such as injection pumps, fuel pumps, pistons, cylinder liners, piston rings, hydraulic oil pumps, operating valves, brakes, and steering systems, but they ignore the filters. Relief valves, various types of appearance and other "small pieces" of maintenance, they think that these "small pieces" do not affect the operation of the machine, even if the damage is irrelevant, just mechanical dynamics to make do with, I wonder if it is these "small The lack of protection of the parts resulted in premature wear of the mechanical attack and shortened life span. Such as diesel engine filter, oil filter, air filter, hydraulic oil filter, water temperature gauge, oil temperature gauge, oil pressure gauge, induction plug, sensor, alarm, glow plug, oil Liquid strainer, tank cover, fuel tank cap, oil filler cap, grease nipple, air reservoir blowdown switch, battery box, fuel injector return joint, split pin, fan wind shield, drive shaft bolt lock, etc. "Small parts" is essential for the normal operation and protection of construction machinery. It is essential for the service life of the extension machinery. If you do not pay attention to the protection and maintenance during the repair work, you will often "because of small losses," resulting in construction machinery. The onset of illness.

Seven, repair taboo forgetting, hidden troubles frequently

When repairing construction machinery, some repair personnel do not understand some of the problems that should be noticed in the repair, resulting in frequent “customary” faults during disassembly, which affects the quality of mechanical repairs. If the hot car removes and disassembles the cylinder head of the engine, it will easily lead to deformation cracking of the cylinder head; when the piston pin is installed, the piston pin will be directly driven into the pin hole without heating the piston, resulting in an increase in the deformation of the piston, an increase in the ellipticity; Connecting copper pads or paper pads on connecting rods can easily block the oil passages and cause the brakes to hold the shaft. When overhauling the bearing bush when repairing the diesel engine, the friction-reducing alloy layer on the surface of the bearing bush is scraped off, causing the steel back and the crankshaft to directly collide with each other. Early onset of wear; no use of pullers when breaking open parts such as bearings and pulleys, and hard knocks, which can easily lead to deformation or damage of parts; unsealing new pistons, cylinder liners, injection nozzles, plunger couples When parts and other parts are used, the oily or waxy materials sealed on the outside of the parts are used to make the parts function to change. This is not conducive to the use of parts.

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