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Damage Main Bearing Connecting Rod Bearing of Diesel Generator

Feb. 24, 2022

Modern production and life are inseparable from electricity. Most enterprises and high-rise residential buildings are equipped with diesel generators as backup power sources. Now the diesel generator brands on the market generally use Perkins, Weichai, Cummins, Yuchai, Shangchai, etc. brand engine. Diesel generators have been used for a long time, and maintenance is inevitable. Diesel generators are a complete set of equipment with many accessories. I believe many friends do not know much about the main bearing and connecting rod bearing of diesel generators. As the main bearing and connecting rod bearing of sliding bearings, the most common failure in use is the peeling or burning of the wear-resistant alloy layer, and the early wear of the bearing.


weichai genset


If the diesel generator runs for a short period of time, the surface of the bearing bush will be quickly damaged or severely worn. Most of the reasons are not the bearing bush itself, but mainly due to the use conditions or poor matching parts or technical conditions. A survey material shows that 44.9% of the damage to the bearing bush is caused by impurities, 13.4% is due to poor assembly, 12.7% is poor concentricity, 10.8% is poor lubrication, 9.5% is overload, and the rest are other factors such as corrosion.


In the process of starting and stopping the diesel engine, the bearings are often in a critical lubrication state, which can cause the oil film to be interrupted and the friction surfaces to be in direct contact. Even when the diesel engine is in normal operation, it is difficult for the journals and bearings to maintain uniform and uninterrupted liquid lubrication due to factors such as unstable load. In addition, the new diesel engine fails to completely remove the molding sand and iron filings during assembly, which can enter the dust and dirt during operation, which is also the main reason for accelerated wear and tear, causing the Lava to burn tiles.


The spalling of the bearing is mainly due to fatigue damage. Because the magnitude and direction of the load on the bearing changes with time, when the load is unstable, a uniform and continuous oil film cannot be maintained between the bearing friction surfaces, and the pressure of the oil film changes pulsatingly. At the minimum oil film thickness, high temperature is generated in the local area of the bearing surface, which greatly reduces the fatigue strength of the alloy layer. In addition, the poor manufacturing and assembly of the bearing itself is also the direct cause of the peeling of the alloy layer.


Due to the difference in the shape of the piston cavity and the difference in the opening of the connecting rod journal of the in-line and V-type diesel engines, the structure of each connecting rod is different. Some models have a long oil hole on the connecting rod body, and a 01.5 hole on the top of the connecting rod, which is used as a nozzle to spray oil into the piston cavity for cooling; there is an oil groove on the surface of the bearing shell; pay attention to the strictness of the upper and lower shells Distinguish, please do not install wrong.


In addition to wear and spalling, the corrosion of plain bearings is also a concern, depending on the quality of the oil, temperature, pressure and bearing load. The high-load parts of the bearing are most prone to corrosion, and the organic acids and sulfides generated by the deterioration of the lubricating oil at high temperatures are the direct causes of bearing corrosion. The burning loss of the bearing, which is commonly referred to as "burning tile", is mainly caused by too small clearance, poor lubrication and problems in use and operation.


If the failure of the main bearing and connecting rod bearing of the diesel generator occurs, it should be stopped immediately, otherwise the crankshaft will lock, the difficulty of repair will increase, and the maintenance cost of the diesel generator will increase. The connecting rod big end bearing bush is generally made of steel-backed high-tin aluminum alloy, and it is positioned with the connecting rod big end hole by the tongue on the bearing bush. During overhaul, if the inner wall of the bearing bush is found to be peeling, scorched, severely strained, and the back of the pad is loose, it should be replaced. For scratches caused by foreign objects, it can still be used after removing foreign objects and trimming.


Starlight Power was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. If you want get more information, please feel free to send email to sales@dieselgeneratortech.com we will pay highly attention on your question.

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