Interlaced like a mountain, some manufacturing industries can only be summarized by masters who have been deeply involved in the manufacturing industry for many years. Today, people want to give everyone some taboos in the whole process of overhauling construction machinery and equipment! Let everyone get twice the result with half the effort on the construction machinery and equipment road, and get immediate results!
Let's follow the web editor and take a look at the top 10 taboos of construction machinery maintenance!
1. Pay attention to the replacement of automobile oil
Automobile oil is indispensable in the application of diesel engine, the key is to moisturize, water cooling, cleaning and other functions.
Therefore, many drivers pay attention to check the remaining oil of the grease and add it according to the specifications, but they ignore the regular inspection of the quality of the grease and the replacement of the already moldy car oil, resulting in some diesel engine fitness sports parts. It runs in a weaker natural environment, which speeds up the damage of various parts.
Under normal circumstances, the consumption of automobile oil is not much, but it is easier to pollute the environment and lose the function of maintaining the diesel engine. In the whole process of diesel engine operation, a lot of wastes (soot, carbon deposits and fouling, etc. converted into fuel ethanol) are entered into the automobile oil.
For new or repaired mechanical equipment, there will be a large amount of residue after trial operation. If you only add it without changing it, it is eager to deliver it for use, which is more likely to cause accidents such as tile burning and axle holding.
In addition, even if the engine oil is changed, some drivers may not completely clean the oil passages when they are dismantled mainly because of the maintenance experience or the convenience of the drawings, so that the residue of the mechanical equipment remains in the oil pan and fuel pipe.
2. The abuse of unsalted butter doodles
Spread unsalted butter on the cylinder head gasket. Unsalted butter is a common lubricating grease in the maintenance of construction machinery and equipment, which has the effect of lubricating and sealing.
Therefore, some maintenance workers will apply a layer of unsalted butter on the cylinder head gasket when installing the cylinder head gasket, feeling that it can improve the airtightness of the diesel engine. But I didn’t know that doing so would endanger the working characteristics of the diesel engine.
Cylinder head gasket is the most critical hydraulic seal between the cylinder block and cylinder head of a diesel engine. It can not only seal the ultra-high pressure steam body created in the cylinder, but also seal the cooling circulating water of the cylinder head and cylinder body. Grease, so when disassembling the cylinder gasket, you must pay attention to its sealing quality.
If unsalted butter is applied to the cylinder head gasket during installation, when the cylinder head anchor bolts are tightened, part of the unsalted butter will be squeezed into the cylinder waterway and oil passage, and the unsalted butter left between the cylinder head gasket will work in the cylinder At medium time, due to high temperature, part of it will flow into the cylinder to ignite, and the other part will remain on the fusion surface of the engine block and cylinder head, causing gaps between the cylinder head gasket, cylinder head and the plan view of the human body. UHP natural gas is easier to get from here. Impact cylinder head gasket damages the cylinder head gasket and causes steam leakage.
In addition, unsalted butter will cause carbon deposits when exposed to high temperatures for a long time, which will lead to premature embrittlement of the cylinder head gasket. Therefore, do not wipe unsalted butter when installing the cylinder head gasket.
3. New cylinder liners and pistons can be installed without options
When refitting the cylinder liner and piston, I feel that the new cylinder liner and piston are all standard parts, and they all have tolerances, so they can be applied after they are installed.
In fact, the specifications of cylinder liners and pistons often have certain dimensional tolerances.
If a larger size cylinder liner is added to the smallest size piston, the clearance will be too large, resulting in reduced fatigue and difficult starting.
Therefore, when refitting, it is necessary to check the specification sequence number of the standard cylinder liner and piston. The installed cylinder liner and piston must make the specification sequence number of the standard piston and the specification sequence number of the standard cylinder liner the same. Only then can they ensure that they have each other. Standard inter-coordination gaps.
In addition, if each cylinder is equipped with cylinder liners and pistons with the same sequence number, attention should be paid to the inspection of the cylinder plug gap before installation. In order to ensure the standardization of the assembly line, an inspection should be carried out before one-key installation to prevent the installation of fake and inferior 名媛直播. commodity.
4. Pay attention when measuring cylinder clearance
When measuring the cylinder gap, it is impossible to measure the orientation of the piston pin hole vertically bisecting the piston journal, and measure it in other orientations.
The structural characteristics of the aluminum alloy piston are small in the top and large in the bottom. It is a cone, and the cross section of the journal is elliptical, so the cylinder gaps along the center of the circle are not the same.
When measuring, it is required to take the gap of the elliptical minor axis as the standard, that is, to measure the gap of the piston pin hole perpendicular to the piston journal.
That measurement is more convenient and accurate, and in repeated motions, the orientation of the piston pin hole that is vertically bisected by the piston journal is greatly damaged due to the effect of the longitudinal working pressure. Therefore, when measuring the cylinder gap, the piston should be bisected vertically on the piston journal. Orientation measurement of pin holes.
5. Transitional fit of piston and piston pin
Because the piston and the piston pin are in a transitional fit, when installing the piston pin, the piston should be heated and deformed. At this time, some maintenance workers will put the piston on the fire and heat it immediately.
That approach is very incorrect. Because the thickness of the piston is uneven, the level of thermal expansion and contraction will be different. Heating with fire will cause uneven heating of the piston, which is very easy to cause deformation; the surface of the piston will also adhere. Carbon dust reduces the service life of the piston.
If the piston is cooled by natural water after reaching a certain temperature, its alloy composition will be damaged and the wear resistance will be greatly reduced, and its service life will be significantly reduced.
When installing the piston pin, you can put the piston in boiling oil to heat it evenly to make it shrink slowly. Do not use fire to heat up immediately.
6. There are ways to polish and polish the piston pin
For some inexperienced maintenance workers, scraping is a job with a relatively high degree of difficulty, because the technicality of scraping is impossible to grasp, so it is not easy for the piston pin to meet the technical standards.
Therefore, in order to enlarge the total contact area between the piston pin and the engine crankshaft when disassembling and replacing the piston pin, many people use sandpaper to polish and replace the scraper.
This type of method is extremely useful in actual maintenance. Because the abrasive grains on the sandpaper are harder, while the aluminum alloy of the piston pin is too soft, it is easier for the sand grains to be embedded in the aluminum alloy during polishing. The diesel engine is working. Time to speed up the damage of the motor shaft and reduce the service life of the engine crankshaft.
7. Remember to not overtighten the anchor bolts
In the whole process of disassembly of construction machinery and equipment, the anchor bolts in many positions are all required to have torque requirements, such as the gear box, cylinder head, rim, crankshaft and front axle assembly. The tightening torque is often specified in the operating instructions. There are professional requirements, please do not change randomly.
However, many application workers mistakenly think that tightening is more secure, but overtightening will cause the screw or anchor bolt to break, and it will also cause common failures due to external thread sliding buckles.
8. The tire pressure standard is too high
The working pressure of tire pumping for wheel test construction machinery and equipment is a key element in determining its service life and work efficiency.
If the tire pressure is too high or too low, it will endanger its service life, and it is also detrimental to safe driving, especially in the hot summer.
The air pressure standard of scientific research should be: take the tire pressure standard of the car tire as the standard, and with the change of the average temperature, it is only right to slightly adjust the tire pressure standard.
For example, the summer is wider than the winter and the lower is 5%-7%. Because the average temperature in summer is high, the steam body is heated, and the working pressure increases, in turn, the tire pressure must be reached or lower in winter.
9. Do not check the capacity of the plunger stroke arrangement
In the ironic test of the plunger diesel pump, many maintenance workers did not pay attention to checking the stroke arrangement capacity of the plunger.
To put it plainly, the stroke arrangement capacity of the plunger refers to the amount of movement that the plunger can move up and down again after the top of the camshaft on the camshaft is higher than all dead points.
Interruption of fuel supply during adjustment may cause accidents. Just after the beginning of the accident, it is often necessary to check the stroke arrangement capacity, because the stroke arrangement capacity of the plunger is related to the damage of the plunger and sleeve specifications.
After the plunger and sleeve specifications are damaged, the plunger needs to be strengthened for a while before the oil supply is interrupted, which may cause an accident, and then interrupt the oil supply, which may cause an accident. delay. After unscrewing the adjusting anchor bolts or using too thick adjusting protective layer pads or gaskets, the least part of the plunger is displaced, which reduces the stroke arrangement capacity of the plunger.
Therefore, when repairing and adjusting the diesel pump, the capacity of this stroke arrangement should be checked first to determine whether the diesel pump still allows adjustment.
During the inspection, the following different methods should be selected according to the different structure of the diesel pump:
a) Rotate the camshaft, after the plunger top is higher than all dead points, remove the delivery valve and high pressure gate valve, and measure with a depth vernier.
b) After the plunger is topped above all stop points, use a screwdriver to pry up the yellow spring seat of the plunger to raise the plunger to the highest peak.
Then insert a thickness gauge between the lower plan view of the plunger and the tappet adjustment anchor bolt for measurement. The standard stroke arrangement capacity of the plunger is about 1.5mm, and the limit stroke arrangement capacity after damage should not be less than 0.5mm.
10. Suddenly add cold water to the water tank if the temperature is too high
Diesel engine overload work, heat pipe heat dissipation is not good, or the water storage tank is too hot, which will cause the water tank temperature to be too high. At this time, if cold water is added immediately, it will cause the cylinder head and engine block to burst.
Therefore, once the temperature of the water tank is found to be too high in the application, emergency measures should be adopted to terminate the work, so that the diesel engine cooling circulating water can automatically reduce the heat.
