Share some loader maintenance and repair methods (2)

1.What is the cause of the strain on the cylinder liner of the loader forklift? How to prevent?

The main manifestations of cylinder liner strain are: percussion sound on the piston in the cylinder; The power of the diesel engine drops; the oil burns, and the exhaust smoke is blue or white; the oil becomes thinner and the pressure drops, etc.

The reasons for the cylinder failure are: ①The cooling system fails, the machine overheats, and the piston expands too much after being heated; ②The amount of engine oil is insufficient, deteriorated or contains impurities, causing poor lubrication; ③The gap between the piston and the cylinder wall is too small (more common in new engines or diesel engines that have just been overhauled) ④The piston ring is broken or stuck; ⑤ The piston pin circlip fails, causing the piston pin to move.

2. What are the measures to reduce the wear of the cylinder liner of the loader forklift?

To reduce the wear of cylinder liner, in addition to taking anti-corrosion and wear-resistant measures in design and manufacture, the following points should be paid attention to in the use and maintenance project:

⑴ Correct start and start After the cold car is started, the car should be warmed up for 3 to 5 minutes under a small accelerator state before starting the bicycle. When it is running at first, it should work with a small load for a period of time, and then work with a heavy load after the temperature rises.

(2) Maintain the normal temperature of the engine If the temperature of the diesel engine is too low, it cannot maintain good lubrication, which will increase the friction of the cylinder wall; if the temperature is too high, the strength of the cylinder will be reduced and the wear will be aggravated. The working temperature is 80℃～90℃. When the temperature exceeds 95°C, the load should be reduced or the machine should be stopped for cooling.

⑶ maintain good lubrication Regularly check and maintain good oil quality, moderate oil level, change regularly and select oil with appropriate viscosity according to season to ensure good lubrication.

⑷ Strengthen the maintenance of “three filters” (air filter, oil filter and diesel filter) This is the main measure to prevent mechanical impurities from entering the cylinder, reduce the wear of the cylinder wall, and prolong the service life of the engine, which is especially important for diesel engines used in loaders that often have high dust content.

⑸ Improve maintenance and quality Carry out maintenance and repair operations in strict accordance with the technical standards specified in the diesel engine operation and maintenance manual. Adjust and control each fitting clearance (opening clearance) to prevent accelerated wear between the piston and the cylinder wall due to improper repairs and maintenance.

3. What are the reasons why the diesel engine of the loader and forklift often flushes the cylinder head gasket?

The cylinder head gasket is burnt by the high temperature gas in the cylinder, which is called “cylinder head gasket”, also known as “burning cylinder head gasket”. After the diesel engine is flushed with the cylinder head gasket, abnormal phenomena such as “bubbling” in the water tank, water in the oil pan, oil emulsification, and exhaust pipe drainage (white smoke) generally occur. The main reasons for the flushing gasket are:

⑴ Deformation of cylinder head The cylinder head is thermally deformed due to the alternating action of high temperature and high pressure gas for a long time; improper disassembly and assembly (not disassembled and assembled in sequence) will also cause deformation. After the cylinder head is deformed, the raised part can not be pressed tightly against the cylinder head gasket, causing high temperature gas leakage and burning the cylinder head gasket.

(2) The heights of the cylinder liner bosses are different, causing the individual cylinders to be loosely sealed. In order to press the cylinder liner and cylinder head gasket on the cylinder block and maintain good sealing performance, it is generally required that the cylinder liner end face boss plane be higher than the cylinder block by a certain size (usually 0.05 ~ 0.12mm), the same diesel engine (or the same cylinder The difference between the two cylinders under the cover) of the cylinder liner protrusion is also specified (usually 0.05mm). If it exceeds the specified value, it may cause insufficient sealing pressure, so that high-pressure and high-temperature gas escapes and damages the cylinder head gasket.

(3) The cylinder head bolts are loose or the tightening torque is not enough When the diesel engine leaves the factory, the operation and maintenance instructions provided by the manufacturer have clear requirements on the torque of the cylinder head fastening bolts. During maintenance, the cylinder head should be tightened in strict accordance with the specified time and method.

⑷ The assembly method of the cylinder head gasket is incorrect or the quality of the cylinder head gasket is poor. ⑸ The machine is not working well, and the cylinder gasket is caused by overheating.

4. What are the reasons for the rise of the bottom oil level of those shell diesel vehicles?

The rise of the oil level in the oil pan means that the oil pan cannot enter the oil pan or the bottom pan. Lubricating oil, providing lubricating oil for lubricating oil, reducing the quality of lubricating oil, but making various moving surfaces unfavorable for the formation of lubricating oil in lubrication; allowing the lubricating oil in the lubricating oil to penetrate into the lubricating oil, making the lubricating oil change and making the lubricating oil play a role. effect. If the main surface of the oil shell is found to rise, check the oil, repair the fault, and replace the base oil with excess grease. Therefore, the reason for the rise of the shell surface is:

(1) A certain cylinder (or several cylinders) of the diesel engine does not work or does not work well Fog caused by the injector needle valve stuck in the open state or low injection pressure If the diesel oil is not well smelted, the diesel fuel injected into the cylinder cannot completely form a mixture and burn, and flows into the oil pan from the piston ring, cylinder liner and side of the piston, making the oil level of the oil pan rise. In this case, the cylinder break method can be used to find which or those cylinders do not work or work badly, find out the fault and eliminate it. Check the injector if necessary.

(ii) The water in the oil pan raises the oil level When the oil pan enters the water, the oil will emulsify. The main reasons for water inflow to the oil pan are: ① The cylinder head gasket is burnt and water leaks. Check the water tank at this time, you will find the phenomenon of “bubbling” and “opening” in the water tank, you should check and replace the cylinder gasket; ② Cracks in the cylinder liner cause the cooling water to penetrate into the cylinder and flow into the oil pan. The cylinder liner should be replaced. In this case, the phenomenon of “turning over” and “opening the pot” of the water tank will also occur. Especially in winter, the phenomenon of cylinder cracking is more common due to “chilling”; ③The water blocking ring of the cylinder liner fails and leaks, and the water blocking ring should be replaced. In this case, the water leaks, and the water tank has no turning bubbles: phenomenon.

(iii) For some diesel engines, due to the damage of the rear oil seal of the crankshaft (or not the skeleton oil seal), if the torque converter leaks oil seriously, the hydraulic transmission oil will leak into the oil pan, which will increase the oil level of the oil. At this time, there is no diesel smell or emulsification in the oil, and the torque converter should be overhauled.