Exam Question
Describe how crankshaft deflections of an auxiliary diesel engine are measured. State how the measurements can be checked for accuracy. Specify with reasons other checks that should be made on the crankshaft. (16)
Class 4 (4th Engineer)
MEP
📅 Jan 2026
Reference Answer
### 1. Procedure for Measuring Crankshaft Deflection
**A. Purpose and Principle**
Crankshaft deflection measurement is a critical diagnostic procedure to assess the alignment of the engine's main bearings. The crankshaft acts as a sensitive beam, and any misalignment in its supporting bearings (due to wear, loose chocks, or hull deformation) will cause the crank webs to either splay outwards or pinch inwards as the crankshaft rotates. This bending is measured using a specialized dial gauge. Consistently high deflections indicate excessive bending stresses, which can lead to fatigue failure of the crankshaft.
**B. Prerequisites**
**A. Purpose and Principle**
Crankshaft deflection measurement is a critical diagnostic procedure to assess the alignment of the engine's main bearings. The crankshaft acts as a sensitive beam, and any misalignment in its supporting bearings (due to wear, loose chocks, or hull deformation) will cause the crank webs to either splay outwards or pinch inwards as the crankshaft rotates. This bending is measured using a specialized dial gauge. Consistently high deflections indicate excessive bending stresses, which can lead to fatigue failure of the crankshaft.
**B. Prerequisites**
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