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Eight Major Causes And Inspection Of Diesel Generator Crankshaft Bending

Mar. 15, 2023

The role of diesel generator crankshaft is to bear the pressure of combustion gas, the repeated inertia force of piston connecting rod group and the centrifugal force of rotating mass. When the crankshaft is bent, it will seriously affect the normal operation of the diesel generator. Then the problem is, what causes the bending of the crankshaft, and how to check?


I. Causes of crankshaft bending and twisting.


1. The internal combustion engine works unevenly and the stress on each journal is uneven.

2. The internal combustion engine is suddenly overloaded, causing excessive vibration of the crankshaft.

3. Internal combustion engines often have "sudden explosion" combustion.

4. The clearance between crankshaft bearing and connecting rod bearing is too large, and it is impacted during operation.

5. The crankshaft bearing has different tightness and the center line is not in a straight line.

6. The ignition time of gasoline engine is too early or one or two spark plugs often fail to ignite.

7. The piston quality of each cylinder is inconsistent.

8. The crankshaft end clearance is too large, and it moves forward and backward during operation.


When the bending and twisting of the crankshaft exceeds a certain value, it will accelerate the wear of the crankshaft and the bearing. In serious cases, it will make the crankshaft crack or even break. At the same time, it will also accelerate the wear of the piston connecting rod group and the cylinder.


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II. Inspection of crankshaft bending and torsion.


1. Inspection of crankshaft bending.

Place the two ends of the crankshaft on the V-shaped frame on the inspection plate, and measure the center level with a dial indicator after the part of the rear end that has not been worn before is the base plane. During measurement, the measuring head of the dial gauge shall be aligned with one or two crankshaft journals in the middle of the crankshaft. After slowly rotating the crankshaft by hand for one turn, 1/2 of the difference between the maximum and minimum readings indicated on the dial gauge is the bending of the crankshaft.


When measuring, the dial indicator should not be placed in the middle of the journal, but at one end of the journal. Otherwise, due to the different circles of the journal, incorrect conclusions will be made about the bending amount of the crankshaft. It must be pointed out that the measured result is an approximate value because it involves the increased error caused by the out-of-roundness of the journal at both ends. Because the directions of out-of-roundness and bending often do not coincide.


Bending is usually expressed by bending runout, which is 2 times of the bending, and its runout generally does not exceed 0.10mm. The center of crankshaft intermediate journal is bent, if it does not exceed 0.05mm, it can not be repaired. If it exceeds 0.05~0.10mm, it can be corrected together with journal grinding. If it exceeds 0.10 mm, it must be corrected.


2. Inspection of crankshaft torsion.

After the bending inspection of the crankshaft, turn the connecting rod journal to the horizontal position, and measure the height difference between the two corresponding connecting rod journals with the dial indicator, which is the degree of torsion. Crankshaft torsion is generally very small, which can be corrected when grinding the crankshaft journal.


Jiangsu Starlight Power Generation Equipment Co., Ltd. was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. The company has a registered capital of 218.88 million yuan. The company covers an area of 86,000 square meters and a building area of 55,000 square meters. There are more than 660 employees, including 456 professional technicians and 106 senior technicians. It has 46 sales and service outlets nationwide. The main products are diesel engines, generator sets, and diesel generators, providing users with a one-stop service of design, supply, debugging and maintenance at any time. Starlight has always insisted on using first-class talents, building first-class enterprises, manufacturing first-class products, creating first-class services, and making every effort to build a first-class domestic enterprise. If any question please feel free to visit our website https://www.dieselgeneratortech.com/ or send email to sales@dieselgeneratortech.com.

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