Repair Method for Burnt Crankshaft of Yuchai Generator Set Engine

The crankshaft of a diesel generator set is an important component of the unit. It is a major rotating part on the engine. After installing the connecting rod, it can convert the up - and - down (reciprocating) motion of the connecting rod into circular (rotary) motion. It is made of carbon structural steel or ductile iron and has two important parts: the main journal and the connecting rod journal. The main journal is installed on the cylinder block, the connecting rod journal is connected to the big end hole of the connecting rod, and the small end hole of the connecting rod is connected to the cylinder piston. It is a typical crank - slider mechanism. The rotation of the Yuchai generator crankshaft is the power source of the engine and also the prime power of the entire mechanical system. Based on the factors causing the burning of the Yuchai generator set engine crankshaft, Dingbo Power, a Yuchai generator manufacturer, provides the following methods for repairing the burned crankshaft for users to learn.

Repair methods for the burned crankshaft of Yuchai generator set engine

1.For slightly scratched or burned crankshafts: When the damage is not obvious, the crankshaft can be polished with 600 - grade sandpaper for continued use.

2.For severely scratched and burned crankshafts: When there are extremely obvious scratches or wear, the crankshaft can be ground and paired with oversized bearings (0.25 oversized). However, during processing, it must be ensured that the transition fillets R3 and R5.i of the crankshaft journal meet the requirements.

3.Replacing a new crankshaft: It is best to perform a dynamic balance test on the crankshaft with the flywheel and clutch installed. Engine vibration is mainly caused by excessive dynamic unbalance of the crankshaft components. These components include the crankshaft, flywheel, clutch, and pulley damper. Each of these parts has undergone dynamic unbalance treatment at the factory. However, if the engine vibrates severely, each part must be checked one by one.

4.Crankshaft deformation: During the installation of the crankshaft, if the crankshaft rotates inflexibly (while the bearing shells and shaft holes are normal), it indicates that the crankshaft may be deformed. The crankshaft should be checked for its camber. If the camber exceeds 0.15mm over the entire length, the crankshaft cannot be used.

5.Burning of bearing shells and journals:

1.Note: If the scratches on the crankshaft journal in the circumferential radial direction (not the axial direction) form grooves and the area is within 2mm, and the journal size does not exceed the tolerance, the journal can be used after polishing. In most engine models, a 205 bearing and a bearing bushing are installed in the large - end inner hole of the crankshaft. When replacing the crankshaft, attention should be paid to ensure that they are not omitted or installed incorrectly.

2.General rules for crankshaft bearing selection: Select the main bearing seat shells with the same color markings according to the color markings on the crankshaft main journal. Red should be paired with red, and blue with blue. According to the A and B markings on the main bearing cap, select the red bearing corresponding to A and the blue bearing corresponding to B.

Installation of the rear oil seal for YC4110, YC4112, and YC6112 engines

For the YC4110, YC4112, and YC6112 engines, the rear oil seal is installed on the engine body through the rear oil seal seat, rather than on the flywheel housing like other engine models. Therefore, the rear oil seal with the seat can be installed at this time.

Installation precautions

1.Apply sealant to the rear oil seal seat gasket.

2.Ensure the proper tightening torque.

3.The distance between the bottom of the rear oil seal seat and the installation plane of the oil pan should be within 0 - 0.08mm to prevent oil leakage at the oil pan gasket.

4.Apply an appropriate amount of engine oil to the big end of the crankshaft during installation, and use a plate to level it and tap it into the oil seal seat.

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