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Failure and Repair of Silent Diesel Generator Crankshaft

Jul. 23, 2021

When the silent diesel generator is in operation, the surface of the crankshaft journal of the silent diesel generator bears a large unit pressure and has a high sliding friction speed. The heat dissipation effect of the journal is poor, and the surface of each journal is extremely susceptible to abrasive wear. Therefore, the silent diesel generator must be inspected on the crankshaft during overhaul, find out the situation, and choose the correct repair or repair method to ensure the fatigue strength and wear resistance required by the silent diesel generator crankshaft. The reason for the tapered wear of the connecting rod journal of the silent diesel generator is that the oil passage leading to the connecting rod journal of the silent diesel generator is inclined. When the crankshaft rotates, under the action of centrifugal force, the smooth silent diesel generator is slippery. The mechanical impurities in the oil gather on one side of the connecting rod journal of the silent diesel generator, which accelerates the wear of the side journal, causing the silent diesel generator to wear in a tapered shape.

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The bending of the connecting rod and the non-perpendicularity of the center line of the cylinder and the center line of the crankshaft will cause the shaft journal to receive uneven force in the axial direction and cause wear and tear. The wear of the main journal of the silent diesel generator is mainly due to the influence of the centrifugal force of the connecting rod, the connecting rod journal and the crank arm, which makes the side near the connecting rod journal of the silent diesel generator and the bearing produce relatively large wear. The stress is concentrated on the rounded part of the shaft journal of the silent diesel generator and around the oil hole, which is easy to produce cracks. The existence of cracks will cause the crankshaft of the silent diesel generator to fracture. Therefore, it is necessary to use a flaw detector to detect whether there is a crack. If there is a circular crack or a longitudinal crack with a crack length of more than 20mm, use a chisel or gas cutting gun to blow it off, and then take corresponding measures after arc welding.


Scratches and burns may also appear on the journal surface. Scratches are mainly caused by the unclean oil of the silent diesel generator, and burns are caused by the burning of tiles of the silent diesel generator due to insufficient lubrication, too thin oil or blockage of the oil circuit. For silent diesel generator connecting rod journals, eccentric grinding and concentric grinding methods can be used. The concentric grinding method is to keep the axial position of the connecting rod journal unchanged after grinding, that is, the crank radius and distribution angle remain unchanged. The eccentric grinding method is to position and grind according to the worn connecting rod journal surface. At this time, the centerline position and crank radius of the silent diesel generator journal have changed. Generally, the crank radius after grinding is larger than the original crank radius, which increases the compression ratio.


The cylinders of the silent diesel generator vary unevenly, and at the same time, the mass center of the entire crankshaft of the silent diesel generator is not on the centerline of the crankshaft main journal, which causes the crankshaft to be unbalanced and causes additional dynamic load when the silent diesel generator rotates. Because the crankshaft of the quiet diesel generator is often damaged in use, and the price is relatively high. For this reason, repairing the crankshaft is very meaningful. We selected 4 S195 diesel engine crankshafts that could not be ground and repaired according to the final repair size, and repaired each main journal and connecting rod journal of the two crankshafts by surfacing and arc spraying, and then generated electricity through silent diesel. After eccentric grinding and normal grinding, the machine is loaded and operated. The eccentric wear results show that the coating is well bonded without peeling or peeling. After installation, the bench runs in and runs at full load.


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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