Exam Question
(a) Describe how crankshaft deflections are measured (6)
(b) State how the measurements can be checked for accuracy (5)
(c) Specify with reason other checks that should be made on the crankshaft (5)
Class 4 (4th Engineer)
MEP
📅 Sep 2022
Reference Answer
### (a) Procedure for Measuring Crankshaft Deflections
**1. Prerequisites and Safety:**
* **Engine Condition:** The measurement must be taken when the engine is in a cold state, as specified by the manufacturer. Thermal expansion when the engine is warm can significantly alter the readings, leading to an inaccurate assessment of bearing alignment. The vessel should be afloat in calm waters with an even keel and no list to prevent hull stresses from being transmitted to the engine bedplate and crankshaft.
* **Safety Precautions:** The engine must be stopped, and the turning gear engaged. The bridge and engine control room must be informed, and warning placards such as "MEN AT WORK IN CRANKCASE" should be prominently displayed at all engine control locations. All indicator cocks on cylinder heads must be opened to prevent compression or vacuum from hindering the smooth turning of the engine.
**1. Prerequisites and Safety:**
* **Engine Condition:** The measurement must be taken when the engine is in a cold state, as specified by the manufacturer. Thermal expansion when the engine is warm can significantly alter the readings, leading to an inaccurate assessment of bearing alignment. The vessel should be afloat in calm waters with an even keel and no list to prevent hull stresses from being transmitted to the engine bedplate and crankshaft.
* **Safety Precautions:** The engine must be stopped, and the turning gear engaged. The bridge and engine control room must be informed, and warning placards such as "MEN AT WORK IN CRANKCASE" should be prominently displayed at all engine control locations. All indicator cocks on cylinder heads must be opened to prevent compression or vacuum from hindering the smooth turning of the engine.
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