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Excavator maintenance matters

September 07,2022

Avoid adding oil but not changing it

Oil is essential in the use of diesel engines, mainly for lubrication, cooling, cleaning and other functions. Therefore, many drivers will pay attention to checking the amount of lubricating oil,
And added according to the standard, but ignored the inspection of lubricating oil quality and the replacement of deteriorated oil, resulting in some engine moving parts always in a poor lubrication environment
during operation, thereby accelerating the wear of various parts. Under normal circumstances, the loss of oil is not large, but it is easy to be polluted, thus losing the function of protecting the diesel engine. in diesel
During the operation of the engine, many pollutants (soot, carbon deposits and fouling generated by incomplete combustion of fuel) will enter the engine oil. For new or overhauled machinery, commissioning
After that, there will be more impurities. If you just add it without changing it and put it into use in a hurry, it is easy to cause accidents such as burning tiles and holding shafts. In addition, even with an oil change, some drivers
Lack of maintenance experience or saving trouble will also not completely clean the oil passages during replacement, so that mechanical impurities still remain in the oil pan and oil passages.The following types of hydraulic excavator should pay particular attention to this issue, for example the chinese logistic equipment hydraulic excavatorand top performance LONKING hydraulic excavator .

2. Avoid using butter indiscriminately

(1) Grease the cylinder head gasket. Butter is a commonly used lubricating grease in the repair of construction machinery, which can play the role of lubrication and sealing. Therefore, some repairmen are installing the cylinder head gasket
When the cylinder head gasket is smeared with a layer of butter, it is believed that this can increase the sealing performance of the diesel engine. As everyone knows, doing so affects the working performance of the diesel engine. car
Heat is the most important seal between the cylinder block and the cylinder head of some oil engines. It can not only seal the high temperature and high pressure gas generated in the cylinder, but also seal the cylinder head and the gas inside the cylinder.
Cooling water and lubricating oil, so when disassembling and assembling the steam gasket, pay special attention to its sealing quality. If you apply butter on the cylinder heat during installation, when the cylinder head bolts are tightened
Part of the butter will be squeezed into the water channel and oil channel of the cylinder. When the cylinder is working, part of the butter will flow into the cylinder to burn due to the influence of high temperature while the cylinder is working.
A part of it remains on the joint surface of the cylinder block and the cylinder head, which makes the gasket, the cylinder head and the plane of the body create a gap, and the high-temperature and high-pressure gas can easily impact the cylinder from the outside to heat and destroy it.
Damaged cylinder head gasket, causing air leakage. In addition, the butter will produce carbon deposits under high temperature for a long time, resulting in premature aging and deterioration of the cylinder head gasket. Therefore, do not smear yellow when installing the cylinder head gasket Oil.Therefore it is important to pay attention to the above issues during the use of the excavator, for example the LONKING land digging hydraulic excavator.
(2) Butter the tire nuts. In order to easily tighten the nuts and prevent rust, many repairmen apply oil to the bolts and nuts of the tires. Actually this is a wrong approach.
Because after the tire nut is tightened, the threads have the feature of self-locking. This is due to the equivalent friction angle between the dry thread helix angle and the dry thread. in a given bolted connection
The lead angle is a certain value, and the equivalent friction angle varies with the friction state between the threads. Obviously, the equivalent friction angle between the threads decreases after oiling, and the self-locking performance of the bolted connection
worse. Therefore, never apply grease or drip oil on the bolts and nuts of the tires. Doing so will cause the nut to loosen and even cause an accident.
3. Avoid installing new cylinder liner and piston without matching
When replacing the cylinder liner and piston, it is considered that the new cylinder liner and piston are standard parts, which are interchangeable and can be used after they are installed. In fact, the cylinder liner and the live
The dimensions of the plug have a certain tolerance range. If the largest size cylinder liner is matched with the smallest size piston, the matching clearance will be too large, resulting in weak compression and difficulty in starting.
Therefore, it is necessary to check the size grouping code of the standard sleeve and the live cold when changing.
The inch grouping code is the same, only in this way can a standard fit gap be guaranteed between the two. In addition, when each cylinder is equipped with a cylinder liner and piston of the same group code, it is also necessary to
Pay attention to the inspection of the plug clearance before installation. In order to ensure the assembly standard, an inspection should be carried out before installation to prevent fake and inferior products from being installed.
4. Do not check the plunger stroke allowance
In the iron test of the plunger fuel injection pump, many maintenance personnel do not pay attention to checking the stroke margin of the plunger. The so-called stroke margin of the column cold refers to the cam on the camshaft of the column cold.
After the item reaches the top dead center, it can continue to move upward. After adjusting the start time of fuel supply, the reason for checking the stroke allowance is that the stroke allowance of stroke play is different from the stroke allowance of the stroke.
Wear of the barrel. After the plunger and the sleeve are worn out, the plunger has to move up for a while before the oil supply can start, so that the oil supply start time is delayed. When unscrewing the adjusting bolt or replacing
After adjusting the thicker pads and spacers, the lowest position of the plunger is moved up, so that the stroke margin of the plunger is reduced. Therefore, when repairing and debugging the oil fountain, first check the rest of the stroke.
amount to determine whether the fuel injection pump is still allowed to adjust. During inspection, the following different methods should be used according to the different structures of the fuel injection pump: a) Rotate the camshaft and push the plunger to the top dead center
Then, remove the oil outlet valve and valve seat, and measure with a depth vernier. b) After the plunger is pushed to the top dead center, use a screwdriver to pry up the spring seat of the plunger spring to make the plunger rise to the highest
point. Then use a thickness gauge to measure between the lower plane of the plunger and the adjusting bolt of the tappet. The standard stroke allowance of column cold is about 15mm, and the limit stroke allowance after wear should not be
less than 0.5mm.
5. Avoid inaccurate measurement of cylinder clearance
When measuring the steam noon clearance, it is not possible to measure in the direction of the piston skirt perpendicular to the piston pin hole, but in other directions. The structure of the aluminum alloy piston is characterized by the upper and lower
Large, it is a cone, and the skirt section is elliptical, so the cylinder clearances along the circumferential direction are not equal. When measuring, it is stipulated that the gap in the direction of the long axis of the ellipse shall prevail.
Measure the clearance of the piston skirt perpendicular to the direction of the piston pin hole. In this way, the measurement is more convenient and accurate, and in the reciprocating motion, the direction of the piston skirt perpendicular to the piston pin hole is affected by
The wear is larger due to the action of lateral pressure. Therefore, when measuring the steam gap, it should be measured in the direction of the vertical working pin hole of the piston skirt.
6. Avoid heating the piston with an open flame
Since the piston and the piston pin are an interference fit, when installing the piston pin, the piston should be heated and expanded first. At this time, some maintenance personnel will place the piston on an open flame.
Direct heating is very wrong, because the thickness of each part of the piston is not uniform, and the degree of thermal expansion and contraction will be different.
It is easy to cause deformation, and carbon ash will adhere to the surface of the piston, reducing the service life of the active cold. If the piston reaches a certain temperature and cools naturally, its metallographic structure will be damaged and cause
The wear resistance is greatly reduced, and its service life is also significantly shortened. When installing the piston pin, the live cold can be evenly heated in hot oil to make it expand slowly, and no open flame can be used
Heat directly.
7. Do not use abrasive cloth to polish the bearing bush
For some inexperienced repairmen, scraping tiles is a difficult job, and it is difficult to grasp the technology of scraping tiles, so it is difficult for the shaft to meet the technical requirements.
For this reason, when replacing the bearing bush, in order to increase the contact area between the bearing bush and the crankshaft, abrasive cloth is used to replace the scraper. This method is extremely inadvisable in actual maintenance
Because the abrasive grains on the abrasive cloth are harder, while the bearing bush alloy is softer, so that the sand grains are easily embedded in the alloy during grinding, and the wear of the journal will be accelerated when the diesel engine is working, shortening the bending time.
service life of the shaft.
8. Do not tighten the bolts too tightly
During the disassembly and assembly process of construction machinery, bolts in many parts have specified torque requirements, such as transmission boxes, cylinder heads, wheel hubs, connecting rods and front axles.
The torque is specified in the manual and must not be changed at will. However, many users mistakenly believe that it is safer to tighten a little bit, but tightening too much can cause screws or bolts.
A broken bolt can also cause a malfunction due to a threaded slip.
9, avoid tire pressure is too high
The tire inflation pressure of wheeled construction machinery is an important factor determining its service life and work efficiency. Too high or too low tire pressure will affect its service life, and at the same time
It is not safe to drive, especially in the hot season, the scientific inflation standard should be: take the standard air pressure of the tire as the criterion, and adjust the tire air pressure as the temperature changes.
Just a little adjustment. For example: summer should be 5%-7% lower than winter, because considering the high temperature in summer, the gas is heated, and the pressure increases, on the contrary, it must reach the standard air pressure or
Slightly lower.
10. Avoid adding cold water when the water tank is opened.
Overloaded engine operation, poor heat dissipation or lack of water in the water tank will cause the water tank to boil. If cold water is added immediately at this time, the cylinder head and cylinder block will burst. therefore
Once the water tank is found to be boiling during use, emergency measures should be taken to stop the operation, so that the cooling water of the diesel engine can cool down by itself.