✅ Vlog Title: MAIN ENGINE CRANKSHAFT DEFLECTION - NANVENTURES
For Aspiring & Future 1st Engineer this video is for you!
1st Engineer is incharge in conducting measurement, inspection & make a report afterwards.
A crankshaft deflection indicator measures if there is any deflection on
the engine's crankshaft. Deflections are measured by detecting the misalignment of main bearings. Both horizontal and vertical misalignment
are checked. In the past, a dial gauge was used for this process.
Bearings wear and alignment are interconnected and a wrong alignment caused by excessive bearing’s wear will cause crankshaft bending and will affect its lubrication. Thus causing and increasing, most of the time,
uneven bearing’s wear which will negatively affect the shaft alignment. Excessive clearance in one main bearing can shift the majority of the load to another main bearing and flexing the crankshaft under load may result in crank journal fatigue and ultimately breakage.
Therefore the change in distance between crank webs, measured during one rotation of the crankshaft is known as crankshaft deflection and is an indirect indication of the crankshaft loading condition.
There is a good maintenance need of periodically measuring the crankshaft deflections to ensure that the shaft alignment remains within allowed limits. Normally the crankshaft deflection is to be checked into the following situations:
Under normal running circumstances, once or twice a year.
In case the ship grounded or touched bottom After replacing main bearing shell and again after approximatively 100 hrs.
Before and after engine overhaul in case of auxiliary engines.
If there is any signs of damaged main bearings
Before commencing the measurements the following conditions must be met:
The vessel must be afloat and even keel, as much as possible into the water.
The crankshaft must rest on all main bearings
Indicator valves must be open
The measurements can be affected by:
the engine temperature (so it might be stated if the engine is cold or at working temperature)
vessel load condition
ambient air and water temperature
The measurement is done by a dial indicator placed at a predefined location between crank webs. The crankshaft is then rotated in one direction and readings are taken at the defined angular locations.
Normally, deflection should be measured at four points on the crank, namely the top, bottom, and two sides. However, in practice, the bottom reading is omitted due to the possibility of fouling by the connecting rod,
and instead readings are taken on either side of the bottom position, yielding a total of five readings from each crank web at the positions specified
Year filmed: 2019
Super late upload.
Credits:
Music on this video: No Copy right Music
Love Aside - Patrick Patrikios
Erik Lund - Tokyo Sunset (Vlog No Copyright Music)
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