6 Piston open flame heating
Because the piston and piston pin are interference fit, when installing the piston pin, the piston should be heated and expanded first. At this time, some maintenance personnel will put the piston on the open fire and directly heat it, which is very wrong. Because the thickness of each part of the piston is uneven, the degree of thermal expansion and cold contraction will be different. The open fire heating will cause uneven heating of the piston, which is easy to cause deformation; Carbon dust will also be attached to the piston surface, reducing the service life of the piston. If the piston cools naturally after reaching a certain temperature, its metallographic structure will be damaged and its wear resistance will be greatly reduced, and its service life will also be significantly shortened. When installing the piston pin, the piston can be evenly heated in hot oil to make it expand slowly. It is not allowed to heat it directly with open fire.
7 Grind the bearing bush with emery cloth
For some inexperienced repairmen, the bearing bush is a difficult job. Because the scraping technology is difficult to master, the bearing bush is not easy to meet the technical requirements. Therefore, when someone replaces the bearing bush, in order to increase the contact area between the bearing bush and the crankshaft, they use abrasive cloth to grind instead of scraping the bearing bush. This method is extremely undesirable in actual maintenance, because the abrasive particles on the abrasive cloth are hard, while the bearing alloy is soft, so the abrasive particles are easily embedded in the alloy during grinding, which will accelerate the wear of the journal and shorten the service life of the crankshaft when the diesel engine works.
8 Bolts are too tight
In the process of disassembly and assembly of construction machinery, the bolts of many parts have specified torque requirements, such as transmission case, cylinder head, tire, connecting rod and front axle. The tightening torque is specified in the manual, and cannot be changed at will. However, many users mistakenly believe that it is safer to tighten it, but tightening it too tightly will break the screw or bolt, and may also cause failure due to thread slipping.
9 The tire pressure is too high
The tyre inflation pressure of wheeled construction machinery is an important factor that determines its service life and working efficiency. Too high or too low tire pressure will affect its service life, and it is not conducive to safe driving, especially in hot summer. The scientific inflation standard should be based on the standard pressure of the tire. With the change of temperature, the tire pressure should be slightly adjusted. For example, the temperature in summer should be 5% - 7% lower than that in winter. Considering the high temperature in summer, the gas will be heated and the pressure will increase, on the contrary, the standard pressure must be reached or slightly lower in winter.
10 Add cold water suddenly when the water tank is boiling
Overload operation of the engine, poor heat dissipation or lack of water in the water tank will cause the water tank to boil. At this time, if cold water is added immediately, the cylinder head and cylinder block will burst. Therefore, once the water tank is found to be boiling in use, emergency measures should be taken to stop the operation and make the cooling water of the diesel engine cool down by itself.
Why do Chinese made generator radiators have the highest cost-effectiveness?