CrankShaft change on a Cruise Liner Big job!
Discussion
And you thought changing the cam belt on your car was a PITA:
ALE_Crankshaft_exchange_MS_Zaandam
The crank weighs 7.5 tonnes, and has to come in through a door at dock level, be turned 90deg then dropped (i should say lowered really) a couple of decks down into the engine room, turned 90 again, then slid sideways under the engine that has been picked 8 feet up in the air to let the old crank out!
ALE_Crankshaft_exchange_MS_Zaandam
The crank weighs 7.5 tonnes, and has to come in through a door at dock level, be turned 90deg then dropped (i should say lowered really) a couple of decks down into the engine room, turned 90 again, then slid sideways under the engine that has been picked 8 feet up in the air to let the old crank out!
I've done a few of these now and they're good fun.
Older ships were far easier, modern ones leave less space, less areas to weld padeyes too and even floor space around the foundation has more pipe work running around it. This is for medium speeds I've worked on, Bergens mainly.
A crank will be replaced once the hardness test comes back too high. We can fit up to 3mm oversize bearings which can be machined in situ but if you get hardness readings of 700 Brunel you would need to turn a 350mm journal into a twig before the hardness drops back to normal levels. Even with splash oil and oil mist systems crank damage doesn't take too long till it's terminal.
Lots of time is spent flushing the system with external pumps and filters, plus you flush all the way back through the crank plugs before finally putting any oil pressure into the engine. The quality of the Pipe shop comes into it as smooth joins and good runs make flushing easy. I've flushed a poorly built ship for a week and was still getting dirt out!
Getting the block in the air also makes the initial cleaning far easier as white metal gets everywhere and ships don't give you much access for removing too much without cutting holes everywhere.
Dave!
Older ships were far easier, modern ones leave less space, less areas to weld padeyes too and even floor space around the foundation has more pipe work running around it. This is for medium speeds I've worked on, Bergens mainly.
A crank will be replaced once the hardness test comes back too high. We can fit up to 3mm oversize bearings which can be machined in situ but if you get hardness readings of 700 Brunel you would need to turn a 350mm journal into a twig before the hardness drops back to normal levels. Even with splash oil and oil mist systems crank damage doesn't take too long till it's terminal.
Lots of time is spent flushing the system with external pumps and filters, plus you flush all the way back through the crank plugs before finally putting any oil pressure into the engine. The quality of the Pipe shop comes into it as smooth joins and good runs make flushing easy. I've flushed a poorly built ship for a week and was still getting dirt out!
Getting the block in the air also makes the initial cleaning far easier as white metal gets everywhere and ships don't give you much access for removing too much without cutting holes everywhere.
Dave!
Howitzer said:
A crank will be replaced once the hardness test comes back too high. We can fit up to 3mm oversize bearings which can be machined in situ but if you get hardness readings of 700 Brunel you would need to turn a 350mm journal into a twig before the hardness drops back to normal levels.
Why does the crank get hard (over time, presumably)?Small crank that, and looks like a small throw, so high revving. I recon that's a gen set. Maybe it's a diesel electric ship?
Nice thing about commercial ships, they're proper. You can cut holes in them to get stuff in, weld them back up, lifting tackle up the ying yang, space and plenty of bodies to do the work.
I work on plastic yachts, they're s
t, and the owners are always complaining about the cost of st. But they don't mind spending a grand on a lobster dinner. I'd give my high teeth to get involved in a project like that.
Nice thing about commercial ships, they're proper. You can cut holes in them to get stuff in, weld them back up, lifting tackle up the ying yang, space and plenty of bodies to do the work.
I work on plastic yachts, they're s
t, and the owners are always complaining about the cost of st. But they don't mind spending a grand on a lobster dinner. I'd give my high teeth to get involved in a project like that.
Well that set me off watching ALE videos. Some serious engineering they get up to! This one is incredible: https://youtu.be/J94-o3BIDFI
Howitzer said:
AER said:
Why does the crank get hard (over time, presumably)?
It will happen when it gets hot due to a beating failure or mostly down to operator error.Dave!
"getting hot" would have to be seriously hot, well above the normal operating temperature of the engine, and would have to include a rapid cool down, otherwise it would get softer, not harder......
It will either be a failure of the bearing, a lubrication issue or a fitment issue.
Bad oil on heavy fuel engines is common as is injector problems making very high peak pressures which hammer the big end journal. The white metal welds itself to the bearing d you will get a black area with the excessive heat. We had a ship where they disconnected the OMD (oil mist detector) which takes crankcase gas and passes it through a light box. The crank was blue up the side of the crank web and he worst I had ever seen, the other 5 cylinders just kept turning till it seized completely.
All the ones I've worked on have been high load shutdowns so will still stay pretty hot for the next hour or so. 60degreee oil temp and 85 degreee water temp, localised temp from he failure I have no clue.
Dave!
Bad oil on heavy fuel engines is common as is injector problems making very high peak pressures which hammer the big end journal. The white metal welds itself to the bearing d you will get a black area with the excessive heat. We had a ship where they disconnected the OMD (oil mist detector) which takes crankcase gas and passes it through a light box. The crank was blue up the side of the crank web and he worst I had ever seen, the other 5 cylinders just kept turning till it seized completely.
All the ones I've worked on have been high load shutdowns so will still stay pretty hot for the next hour or so. 60degreee oil temp and 85 degreee water temp, localised temp from he failure I have no clue.
Dave!
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