Maintenance is an effective way to restore the truck performance and prolong its service life. However, in actual operation, use and maintenance personnel have many mistakes in practice, affecting the normal use of heavy truck.
1, not only do not change oil
Oil is essential in the use of diesel engines, mainly from lubrication, cooling, cleaning and other functions. Therefore, many drivers will pay attention to check the oil amount of oil, and by standard addition, but ignored the lubricating oil quality inspection and had deteriorated oil change, leading to some engine moving parts are always in poor lubricating environment operation, thereby accelerating the parts abrasion. Under normal circumstances, the loss of oil is not large, but it is easy to pollution, thus losing the role of the protection of diesel engines. In the diesel engine operation process, many contaminants (incomplete combustion of fuel, soot and carbon deposition and fouling) will be entered into the oil. For the new or after the overhaul of the machine, after the trial operation of impurities will be more, if only do not change on the eager to put into use, it is easy to cause burning tile, shaft and other accidents. In addition, even if the replacement of oil, some drivers due to the lack of experience or the maintenance plan, will also be replaced when not thorough cleaning oil, so that the mechanical impurity still remain in the oil pan and oil.
2, avoid butter with chaos.
(1) Baotou beiben heavy duty truck accessories butter cylinder pad. Butter is a kind of grease used in the repair of construction machinery. Therefore, some workers in the installation of cylinder pad, the cylinder pad will be coated with a layer of butter, that can increase the sealing of the diesel engine. As everyone knows, this will affect the performance of the diesel engine. Cylinder pad is a diesel engine cylinder block and cylinder head are among the most important of the seal, it can not only seal of high temperature and high pressure gas generated inside the cylinder, but also can seal the cylinder cover and the cylinder cooling water and lubricating oil, so in the disassembly of cylinder pad, should pay special attention to its sealing quality. If the installation on the cylinder pad butter, when the cylinder head bolt, a part of the butter will be squeezed into the cylinder and the oil path channel, in between the cylinder pad butter in cylinder working, as affected by high temperature, some people will flow in cylinder combustion, the other part is left in the cylinder and the combination of the cylinder head surface, so that a gap is generated between the cylinder head and cylinder pad, body plane, high temperature and high pressure gas easily from the impact of cylinder liner, cylinder gasket destroyed, resulting in leakage. In addition, the butter long time under the condition of high temperature and produce coke, causing the cylinder gasket premature aging deterioration. Do not grease the cylinders when installing them.
(2) Baotou beiben accessories tire nut butter. In order to prevent corrosion and to tighten the nut, a repairman in the tire bolt nut oil. In fact, this is a mistake. Because of the tightening of the screw nut, the thread has self-locking characteristics. This is due to the fact that the helix angle is less than the equivalent friction angle between the threads. In the given bolt connection, the spiral rise angle is a certain value, and the equivalent friction angle changes with the friction state of the thread. Obviously, after the thread of oil equivalent friction angle decreases, the bolt connection self-locking performance variation. Therefore, on the tire bolts and nuts must not be coated with grease or drops of lubricating oil. In doing so, it will loosen the nut, and even lead to accidents.
3, avoid cylinder liner and piston new products without the optional installation
The replacement Baotou beiben parts cylinder and piston, cylinder and piston that are standard parts are interchangeable, installed you can use. In fact, the cylinder sleeve and piston size has a certain tolerance range. If the maximum size of the cylinder sleeve with the smallest size of the piston, will make the gap is too large, resulting in compression weakness, difficult to start. Therefore, we must change size grouping code check standard of cylinder liner and piston, fitted with the cylinder liner and piston size grouping code must be standard piston size grouping code and standard cylinder, the only way to ensure that the clearance between the two is the standard. In addition, the cylinder liner and piston cylinder is installed with the same grouping code at the same time, we must pay attention to dress before the test cylinder plug gap, in order to ensure the assembly standard, in front of the machine should also conduct a test, to prevent fake defective products.

4, do not check the plunger travel allowance
The plunger type fuel pump ‘s trial, many maintenance personnel do not pay attention to check the piston travel allowance. The so-called plunger stroke margin refers to the camshaft is the top of the camshaft on the top of the check point, but also to continue the upward movement. After the start of the adjustment of the oil, the reason why to check the trip margin, because the plunger stroke margin and plunger, the wear of the sleeve. Plunger and sleeve wear, the plunger to move more than a period of time to start the oil supply, so that the start time to delay oil. When the adjusting bolt is adjusted or replaced with a thicker adjusting cushion block and a shim, the lowest position of the plunger is moved up to reduce the stroke allowance of the plunger. Therefore, in the maintenance of fuel injection pump, the first should check the margin to determine whether the fuel injection pump is also allowed to adjust. Inspection, according to the different structure of the fuel injection pump using the following different methods: a) turn the camshaft, the plunger top to the top of the valve, remove the oil valve and valve seat, with the depth vernier measurement. After the plunger is pushed to the top of the B, the spring seat of the plunger spring is screwed up with a screwdriver, so that the plunger is raised to the highest point. Then use the measuring feeler inserted between plane and tappet adjustment bolt plunger. The standard stroke allowance of the plunger is about 1.5mm, and the limit travel allowance should not be less than 0.5mm.
5, avoid cylinder gap measurement is not allowed
When measuring cylinder clearance, it can not be measured in the direction of the piston skirt perpendicular to the pin hole of the piston. Aluminum alloy piston structure is characterized by the upper and lower, a cone, and the local section of the oval, so the circumferential direction of the cylinder gap is not equal. When measuring, the clearance in the direction of the long axis of the ellipse is specified, that is, the clearance of the piston skirt perpendicular to the direction of the piston pin hole is measured. This measurement is more convenient and accurate, and in the reciprocating movement of the piston skirt, perpendicular to the direction of the piston pin hole by lateral pressure and greater wear and tear, so that the measuring cylinder clearance, should be measured at the piston skirt is perpendicular to the direction of the piston pin hole.
6, avoid piston open flame heating
As the piston and the piston pin is fit, so in the installation of piston pin, piston expansion should be made, then, some repair personnel will be placed on the fire piston heat directly, this approach is very wrong, because different parts of a piston uneven thickness, thermal expansion and cold contraction rate will be the same, the fire heating can make the piston uneven heating, easy to cause deformation; piston surface also attached ash, reduce the service life of the piston. If the piston reaches a certain temperature after natural cooling, the metallographic structure will be damaged and wear resistance greatly reduced, its service life will be significantly shortened. In the installation of piston pin, the piston is placed evenly in the hot oil heating to slow expansion, must not use direct fire heating.
7, do not use emery cloth polishing pad
For some less experienced repairman, Bush is a difficult work, because the scraping technique is difficult to master, so the bearing is not easy to meet the technical requirements, therefore, there are people in the replacement bearing, to enlarge the contact area of the bearing and shaft, use emery cloth grinding instead of scraping. This method is not desirable in actual maintenance, because the abrasive emery cloth hard, and bearing alloy is soft, so the grinding sand is easy to be embedded in the alloy, the diesel engine will accelerate the shaft neck wear, shorten the service life of the crankshaft.
8, avoid bolt too tight
Engineering machinery in the process of disassembly, many parts of the bolts are specified torque requirements, such as transmission box, cylinder head, tires, and other parts of the connecting rod and the front axle, tightening torque have special provisions in the instructions, must not arbitrarily change. However, many people mistakenly believe that the tightening will be more secure, but too tight screw will cause the screw or bolt broken, or may be due to thread slide caused by failure.
9, avoid tire pressure is too high
Tire inflation pressure is an important factor to determine the service life and working efficiency. Tire pressure is too high or too low will affect its service life, but also not conducive to safe driving, especially in the hot summer. Scientific inflatable standards should be: the standard tire pressure as the benchmark, with the change in temperature, the tire pressure slightly adjusted. For example: the summer should be lower than the winter 5%-7%, due to taking into account the high temperature in summer, the heat of the gas, the pressure increased, on the contrary, the winter must meet the standard pressure or slightly lower.
10, avoid water tank boiling sudden cold
Engine overload operation, bad heat or water tank of water will cause water tank boiling, if immediately add cold water, will lead to the cylinder head and the cylinder block cracking. Therefore, the use of once found water tank boiling, should take emergency measures to stop the operation, the diesel engine cooling water to cool.