Engine Crankshaft Failure, These Common Damages Need to be Known

The crankshaft is the most important part of the engine. Crankshaft rotation is the power source of the engine, but also the source power of the entire mechanical system, which requires the crankshaft has sufficient strength and rigidity, journal surface needs to be wear-resistant, work uniformly, well-balanced, to meet these requirements of the crankshaft in order to protect the normal operation of the engine. Of course, with the increase in the use of time, any device may fail again, the engine crankshaft common damage and failure of the following kinds.

1. Crankshaft journal wear

After the crankshaft journal is worn, the clearance between the crankshaft journal and the shaft tile increases, and abnormal sound is made during operation, and the working condition deteriorates. The main reasons are: ① oil is too little or the presence of hard abrasives in the oil, oil deterioration containing acidic substances. ② journal and shaft tile clearance is too large or too small, resulting in oil film is difficult to form, dry friction will occur early wear. ③ diesel engine long-term overload, diesel engine work in overheating conditions, will soon wear. ④ crankshaft rotation, under the action of centrifugal force, mechanical impurities in the oil bias to the side of the oil hole, become abrasive, so that the journal wear unevenly, resulting in taper. ⑤ Connecting rod bending, twisting and cylinder liner skewing, so that the force acting on the crankshaft is not evenly distributed, will also produce taper.

2. Cracks on the crankshaft journal surface

Cracks on the surface of crankshaft journals occur mostly at the rounded corners of the transition between the crankshaft and the journals, as well as at the oil holes. The former is a radial crack, which is very harmful and can easily cause the crankshaft to break, resulting in a major accident; the latter is an axial crack, which develops axially along the oil hole.   The reasons for cracks are mainly caused by manufacturing and repair defects and improper use: ① In use, the journal surface roughness is poor, there are indentations, scratches, corrosion, grinding pits and other defects, here is the origin of stress concentration, such as failure to eliminate in time, fatigue cracks first arise from here and development. ② Insufficient lubrication occurs serious burning tile, will cause axial cracks. ③Long-term use, metal fatigue transition on the journal surface will cause circumferential cracks. ④ The radius of the rounded shoulder after grinding is too small, the transition is not smooth or the surface roughness is poor, causing stress concentration. ⑤ When repairing the journal by surfacing, excessive residual stress is generated in the surface layer, which causes cracks.

3. Crankshaft deformation

Crankshaft deformation is usually bending and torsional deformation. Excessive deformation of the crankshaft will lead to increased wear and tear of itself and the connected parts, accelerated fatigue, crankshaft fracture and excessive mechanical vibration.

The causes of crankshaft deformation are non-human causes and human causes. Non-human causes: crankshaft deformation due to cyclic gas pressure, reciprocating inertia, centrifugal force and mechanical braking force of rotary motion.

Man-made causes are mainly violations of driving procedures and accidents caused by mechanical failure: ① heavy load, start too hard. ② diesel engine work rough, so that the crankshaft is subjected to sudden impact load. ③ speeding or flying, in order to make the diesel engine emergency flameout, take too violent braking measures. ④ Diesel engine due to lack of lubricating oil or axial tile clearance is too small and burned tile holding shaft accident, so that the crankshaft is subjected to a large torque. ⑤ The cylinder block main bearing seat hole is not concentric after serious deformation.

4. Crankshaft fracture

Crankshaft fracture usually starts from the smallest crack, and most of the cracked parts are found in the head cylinder or the end cylinder connecting rod journal round corner and crank arm joint part. Diesel engine in the operation process, the crack gradually expand, to a certain extent when the sudden fracture. There are probably several reasons for crankshaft fracture. ① The rounding angle of the crankshaft journal ends is too small. ② crankshaft main journal axis offset, destroying the dynamic balance of the crankshaft assembly, diesel engine high-speed operation will produce a strong inertia force, resulting in crankshaft fracture. ③ The crankshaft is too cold. ④ Loose flywheel. ⑤ Poor quality of crankshaft itself.

Engine crankshaft is very important, if there is a failure, you need to repair or replace it in time. If you are still hesitating where to buy engine crankshafts, you can take a look at the official website of Keluo Construction Machinery, a strong manufacturer of new and used construction machinery, engines and parts. Keluo Construction Machinery is a strong manufacturer of new and used construction machinery, engines, and parts. They have a large inventory of genuine spare parts to ensure that customers can find the right part for their engine needs, and most importantly, Keluo Construction Machinery sells European labeled, German quality items, and they produce high quality parts that are built to last. If you have any related needs or would like more information, please feel free to contact us and we look forward to working with you.