Exam Question
(a) What is crankshaft misalignment? (4)
(b) What are the reasons for crankshaft misalignment? (8)
(c) What is the effect on main engine of such misalignment? (4)
Class 4 (4th Engineer)
MEKM
📅 Jan 2026
Reference Answer
### (a) What is Crankshaft Misalignment? (4 Marks)
Crankshaft misalignment is the condition where the rotational centers of the main bearing journals deviate from a perfectly straight line, known as the bore axis. This deviation can occur in both the vertical and horizontal planes.
In an ideal state, the entire crankshaft assembly is supported by main bearings whose centers form a co-linear axis. Misalignment introduces a situation where the crankshaft is no longer straight, causing it to bend with every revolution. This bending induces alternating tensile and compressive stresses, primarily in the crank webs, which can lead to fatigue failure.
Key characteristics of misalignment include:
Crankshaft misalignment is the condition where the rotational centers of the main bearing journals deviate from a perfectly straight line, known as the bore axis. This deviation can occur in both the vertical and horizontal planes.
In an ideal state, the entire crankshaft assembly is supported by main bearings whose centers form a co-linear axis. Misalignment introduces a situation where the crankshaft is no longer straight, causing it to bend with every revolution. This bending induces alternating tensile and compressive stresses, primarily in the crank webs, which can lead to fatigue failure.
Key characteristics of misalignment include:
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