Requirements for The Use of Connecting Rod Bolts in Diesel Generators 1

The interruption and cracking of connecting rod bolts in diesel generators during operation will lead to serious cylinder ramming accidents. This not only damages the cylinder head and liner, causing deformation and bending of the connecting rod, but also causes significant economic losses such as crushing the engine body and breaking the crankshaft. To avoid cylinder tampering accidents caused by broken connecting rod bolts, the following 14 points should be noted during use and maintenance:

1. Connecting rod bolts bear significant alternating impact loads during diesel engine operation and are important components of diesel engines. It is made of high-quality alloy steel through quenching and precision processing, with high strength and impact toughness, and cannot be replaced by ordinary bolts or inferior parts. If the material, heat treatment, and processing accuracy of the bolt do not meet the technical requirements, it will lead to insufficient mechanical strength and deformation and fracture accidents.

2. Carefully inspect before assembly. When scratches, slippage, cracks, dents, necks, or cracks are found on the bolt (using immersion or magnetic testing methods), or the bolt and nut fit is loose, or the bolt cannot fit tightly with the bolt hole, or when observed by comparison, if the bolt length is 2% longer than the new standard bolt, it should be replaced.

3. Check the clearance between the connecting rod bearing and the connecting rod journal. If the clearance is too large, it can easily lead to the fracture of the connecting rod bolt. At this time, a new connecting rod bearing should be replaced or an enlarged bearing should be used, and it should be selected or repaired.

4. Check the fit between the connecting rod bolts or nuts and the supporting surface of the connecting rod end cap. If there are burrs or unevenness, they should be polished. Otherwise, the connecting rod bolts are easily broken due to additional torque.

5. During assembly, use a torque wrench to alternately and evenly tighten the connecting rod bolts in three or four steps (usually three or four times) to the specified torque. If the tightening torque is insufficient, gaps will appear on the connecting rod joint surface during operation, and the bolt is prone to being pulled or cut when subjected to impact force; If tightened too tightly, the bolt will elongate and deform, resulting in a decrease in strength and easy breakage and damage under stress.

The specified torque for connecting rod bolts of various diesel engines varies. In the absence of technical information, the safe torque range can be estimated based on the bolt diameter. The safety torque of M10 bolts with a strength level of 12.9 is 60-80N. m; M12 bolt, with a torque of 80-100N. m; The M14 bolt has a torque of 100-120N. m.

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