What do you know about the top 10 no-no’s of excavator repair?
1. Oil only added but not changed
The use of oil in diesel fuel is essential, first of all, to play the effect of smoothing, cooling, cleaning and so on. So many driver will pay attention to the amount of smooth oil, and increase according to the norms, but ignored the quality of the smooth oil and the oil has been deteriorated oil replacement, resulting in some of the engine running in the environment is not smooth enough to accelerate the wear and tear of the various parts of the machine. Under normal circumstances the oil loss is not great, but it is easy to be contaminated, and then lose the effect of maintaining the oil. In the operation of the diesel engine, many dirt(fuel incomplete carbon soot carbon and scale,etc.)will enter the oil. After the test run impurities will be more, join only add not change in a hurry to put into use, it is easy to lead to burning tile or hold the shaft and other accidents. And also in the replacement of not completely clean the oilway, so that mechanical impurities remain in the oil pan and oilway.
2. Messing around with butter
Grease the cylinder gasket. Grease is the most commonly used grease in construction machinery and provides a smoothing and sealing effect. Therefore, some maintenance workers will apply a layer of grease on the surface when installing the air cushion cylinder, thinking that this can increase the airtightness of the diesel engine. Unbeknownst to them, this instead affects the working function of the diesel engine. Air cushion cylinder is most importance seal between the diesel engine cylinder and cylinder head, it not only seals the high temperature and high pressure gases occurring in the cylinder cooling water and lubricating oil, so in the dismantling and installation of the air cushion cylinder,pay attention to the quality of its sealing.
For example, when installing the cylinder gasket coated with grease, when the cylinder head bolts are tightened, a part of the grease will be squeezed into the cylinder channel or oil channel, stay in the cylinder incineration, and the other part other inflow into the cylinder incineration, and the other part of the residual in the cylinder and the cylinder head of the contact surface, so that the cylinder cushion,the cylinder head and the plane of the body of the gap between the high-temperature and high-pressure gas can easily be impacted from here! The high temperature and high pressure gas can easily impact the cylinder gasket from here, resulting in the destruction of the cylinder gasket to form gas leakage. In addition, the grease is still in a high temperature state for long time, carbon deposits will occur, the formation of premature aging of the cylinder gasket metamorphosis. Therefore, do not apply grease when installing the cylinder gasket.
3. Cylinder liner and new piston products are directly mounted without option.
When replacing the cylinder liner and piston, it is assumed that the new cylinder and piston are standardized parts and are interchangeable, so they can be used when installed. In fact, the cylinder liner and piston size have a certain tolerance range, Such as the largest size of the cylinder liner and piston size have a certain tolerance range. Such as the largest size of the cylinder liner with the smallest size of the piston, will make the activities of the gap is too large, the formation of the tightening of powerlessness, start difficult!
Replacement must check the norm cylinder liner and piston scale grouping code,the size of the piston grouping code and the size of the norm cylinder liner grouping code is the same, only so as to ensure that there is a standardized gap between the two, but also pay attention to the inspection, in order to ensure that the impact of the former but also to carry out a test in order to prevent the mounting of the counterfeit and shoddy defective product.
4. Heating by open fire with gas piston
During the installation of the piston pin, the piston should first be allowed to expand by heat. Many repairers heat them directly over an open flame for the sake of convenience. However, because the thinness of each part of the piston is not uniform, placing it on an open fire will cause deformation. Therefore, the correct method should be to put the piston into the hot oil for heating.
5. Cylinder air measurement error
Failure to measure cylinder air with the piston skirt perpendicular to the piston pin hole and in the other direction. The aluminum structure is a cone with a small top and a large bottom, and the skirt section is an oval, so the cylinder air gap along the circumference is not flat. Measurement, the rules of the ellipse long axis direction of the clearance shall prevail, that is, the measurement of the piston skirt perpendicular to the piston pin hole position.
6. Sanding of tile shafts with gauze
For some inexperienced maintenance workers, scraping tile is a difficult job, due to scraping tile skills are difficult to master, so the tile shaft is not easy to meet the needs of the use for this reason, some people in the replacement of the tile shaft, in order to increase the contact area between the tile shaft and the crankshaft, it is sanded with gauze as an alternative to scraping the tile. This approach in the actual maintenance is highly undesirable, due to the gauze on the abrasive particles harder, while the alloy of the axial tile is softer, so that in the grinding sand particles are easily embedded in the alloy, diesel engine work will accelerate the wear of the journal, shorten the service life of the crankshaft.
7. Bolt tightened too tightly
Construction machinery in the disassembly process, many parts of the bolt is a standard torque requirements, such as the transmission box, cylinder head, wheel hubs, connecting rods and front axle and other parts of the tightening torque in the manual have special provisions, do not arbitrarily change.
However, many users mistakenly believe that some of the tighter will be more secure, but screwed too tightly will cause screws or bolts broken, but also may be due to thread slippage and cause failure.
8. Tire pressure too high
In the process of inflating tires, many mechanics do not pay attention to the problem of tire pressure. Wheeled construction machinery tire inflation pressure is an important factor in determining its service life and efficiency. Tire pressure is too high or too low will affect its service life, not conducive to safe driving, especially in the hot summer.
Scientific inflation norms should be: to the standard tire pressure as a benchmark, followed by changes in temperature, the tire pressure slightly adjusted to the right. For example: summer should be lower than the winter 5% -7%, taking into account the high summer temperatures, gas heating, pressure increases, on the contrary, it is necessary to reach the normative air pressure in winter or a little lower.
9. Do not check the plunger stroke allowance
In the plunger injection pump test, many maintenance personnel you do not pay attention to check the plunger stroke margin. The so-called plunger stroke margin, refers to the plunger by the camshaft cam top to the upper stop, but also can continue to move up the amount of movement.
The reason for checking the travel allowance after adjusting the oil supply start time is that the travel allowance of the plunger is related to the wear of the plunger sleeve. After the plunger and sleeve wear, the plunger has to move upward for a period of time before the oil supply is started, and then the oil supply start time is delayed. When unscrewing the adjusting bolt or using thicker adjusting pads and shims, the lowest side of the plunger moves upward, so that the plunger’s travel margin decreases.
10. Water tank boiler suddenly add cold water
Engine overload, poor cooling or water tank will form a water tank pot, if you immediately add cold water, will lead to the cylinder head and cylinder burst. Therefore, the use of the water tank once found in the pot, should take emergency measures to suspend work, so that the diesel engine cooling water cooling itself.
Post time: May-22-2024