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Repair and Inspect The Crankshaft of Cummins Diesel Generator Set

Nov. 29, 2021

How would you repair and inspect the crankshaft of Cummins diesel generator set? The crankshaft is the final component of a Cummins diesel generator set. It is subjected to complex forces and working conditions, the sliding speed of each friction surface is high, and the heat dissipation conditions are poor, so the crankshaft is not only easy to wear on the journal, but also bends and twists, and even cracks or breaks. Once a failure occurs, it will seriously affect the efficiency of the Cummins diesel generator set. Therefore, checking and repairing the crankshaft is a very important maintenance step. So how to check and repair it, here is a brief introduction. The crankshaft cracks are so fine that they are not easy to see with the naked eye, and can be inspected with a magnetic flaw detector.

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When the conditions are not available, the easiest inspection method is the oil immersion hammering method: first immerse the crankshaft in kerosene for a while, take it out and clean it, sprinkle it with white powder, and then hit the crankshaft arm in sections with a hand hammer. Due to the vibration, the kerosene in the crack seeps out, causing the white powder to show oil stains and yellow lines. Based on this, the position and length of the crack can be determined. The most obvious part of crankshaft bending deformation is the middle main journal. If the crankshaft is continuously used after bending and deformation, it will accelerate the wear of the crankshaft connecting rod mechanism, and even cause cracks and fractures in the crankshaft. Therefore, this must be checked during engine repairs.

During inspection, both ends of the crankshaft should be supported on the V_-shaped frame on the platform, and the dial indicator contacts should be placed against the middle main journal avoiding the oil hole, and the crankshaft should be slowly rotated for one week, and the indication on the dial indicator should be observed. One half of the difference between the maximum value and the minimum value is the straightness of the crankshaft. If the crankshaft has eccentric wear, the amount of eccentric wear should be subtracted. When the straightness is within the range of 0.05~0.10mm, it can be combined with journal grinding for correction. The method of checking the torsion angle of the crankshaft is to support the crankshaft horizontally on the platform so that the two journals of the same connecting rod are at the top dead center, and then use a dial gauge to measure the height difference between the front and rear connecting rod journals at their highest points. The larger the value, the larger the twist angle.

The main journal and connecting rod journal of the crankshaft will inevitably be worn during work, and the wear is uneven, which is mainly manifested by the roundness of the journal, the cylindricity exceeding the standard value and the strain. The most worn part of the connecting rod journal is generally on the inner side of each journal, that is, on the side of the crankshaft centerline, so that the journal is out of round; and the part that wears into a cone is generally on the side of the lubricating oil passage where impurities are attached. On the side and the place where the force is large. The wear parts of the main journal of the crankshaft vary according to the degree of strengthening of the engine, the number of cylinders, the length of the crankshaft and the counterweight of the balance weight, and the wear of the journal is more even than that of the connecting rod journal. Practice has shown that the wear of the connecting rod journal is faster than that of the main journal, and the main journal wear is more serious than the wear of the connecting rod journal. Find out the worn parts according to the law of wear of each journal. The roundness and cylindricity can be measured with an outside diameter micrometer to determine the repair level and grinding size of the crankshaft.

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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