In order to prevent the crankshaft from breaking, the following measures can be taken during maintenance:

First of all, before repairing the crankshaft, carefully check whether the crankshaft has cracks, pay special attention to the transition part of the fillet, if there are cracks, the shaft should be scrapped. When polishing the journal, the journal and crank arm should maintain a certain radius of fillet. The size of the fillet should not be reduced arbitrarily. Pay attention to the surface finish of the fillet, otherwise it will cause stress concentration and cause the crankshaft to break.
Secondly, when the journal size wear exceeds the limit, it is necessary to choose a method that has less influence on the fatigue strength of the journal to restore it. For example, the reduction of fatigue strength of crankshaft journals by spray coating method is less, and when recovery by surfacing method, the reduction of fatigue strength is larger.

Then, the matching clearance and end clearance of each journal and bearing should be in accordance with the standard. If the clearance is too large, the crankshaft may be easily damaged due to impact. If the clearance is too small, the crankshaft may be broken due to the shaft. In terms of assembly, the ignition time should be calibrated accurately, not too early or too backward, and pay attention to the balance of the crankshaft, flywheel and clutch.