Exam Question

### (a) Procedure for Taking Crankshaft Deflections and Precautions
Crankshaft deflection measurement is a crucial diagnostic procedure performed on large reciprocating engines, particularly marine diesel engines. It provides an indication of the alignment of the main bearings and the integrity of the engine's bedplate and foundation. Misalignment can lead to premature bearing wear, crankshaft fatigue, and potential catastrophic failure. The procedure and precautions must be observed meticulously to ensure accurate and reliable readings.
**1. Concept and Purpose:**
Crankshaft deflection readings measure the relative vertical and horizontal displacements of the crankwebs as the crankshaft rotates through one complete revolution. These readings reveal any bending stresses imposed on the crankshaft due to misalignment of the main bearings, which can arise from issues such as uneven bearing wear, bedplate distortion, hull sag/hog, or foundation problems.