Description

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Con Rod Bearing Kit 276134

The main bearing shells and connecting rod shells on the engine are among the precision components of the engine. However, as the operating time increases, the bearing shells may experience fatigue shedding, mechanical damage, and even cracking. This not only affects the normal operation of the engine but also significantly shortens the service life of the bearing shells. For common damages to the bearing shells, specific analysis based on the specific situation is required. Faulty causes should be eliminated to extend their service life and ensure the normal operation of the engine.

Wearing of the Bearing

Wearing of the bearing refers to the phenomenon where, due to the lack of lubricating oil or a too-small gap between the main journal of the crankshaft and the bearing, or between the connecting rod journal and the connecting rod bearing, the oil film breaks, causing direct contact between the bearing surface and the journal, resulting in dry friction and even seizing of the shaft. This can lead to fire or even complete seizure of the shaft.

Causes

(1) Lack of oil. The oil pump fails, resulting in insufficient oil pressure; the oil passage is blocked, the filter or filter element is too dirty or clogged, the bypass valve fails, the bearing is assembled too tightly or the bearing is too short, the bearing seat rotates, and the oil passage is blocked, causing the bearing to lack lubricating oil and resulting in bearing wear.

(2) Excessive clearance between the bearing and the journal, low oil film pressure, too-small clearance, or the bearing is raised too high, the alloy at the bearing opening deforms, during operation the contact area between the two friction surfaces is much larger than the specified value, causing a sharp increase in friction heat, etc., which leads to the destruction of the bearing.

(3) The roundness and cylindricity of the crankshaft journal exceed the tolerance limit, unable to form an oil film.

(4) The crankshaft is bent or the main bearing hole is not concentric enough.

(1) The engine oil is not clean. During the processing of parts such as the cylinder block and crankshaft of the diesel engine, metal shavings and other debris are left in the cylinder block, crankshaft, oil pump, oil passage holes, and on the inner wall of the cylinder. There are also metal shavings, molding sand that were not thoroughly cleaned off before assembly, as well as dust and impurities that remained in the diesel engine during assembly.

(2) The surface roughness of the journal is poor, or the running-in process was not carried out in accordance with the specified requirements. During the high-speed and heavy-load running-in period, the surface of the bearing bush was scratched.

(3) Before leaving the factory, the crankshaft bearing bush was coated with a layer of anti-rust oil on its surface. Before assembly, the anti-rust oil on the bearing bush should be cleaned off to avoid the anti-rust oil being heated and diluted during the operation of the diesel engine, mixing with the diesel engine lubricating oil, increasing the impurities in the oil and accelerating the deterioration of the oil.