Any marine engineers here 1

You're probably better off in the automotive engineers Engine and Fuel engineering or mechanical engineering forums.

This one tends to be about marine structures.

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Also: If you get a response it's polite to respond to it.

There are not many there that have experience with large marine engines.

I spent most of my sea time on steamers and now operate a fleet of high speed diesels which aren't much different than automotive engines. But I am familiar with medium speed engines and have knowledge of slow speed engines.

Wasn't sure if Tug looked here and you won't find anyone better so ask away.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

What size and type engines are you looking for info on? Large two stoke slow speed engines in the 10,000 bhp plus range? Medium speed engines in the 4,000 to 10,000 bhp range? Or something else?

My early experience was a mix of older design slow speed engines like Atlas Imperials, Enterprise and Fairbanks Morse, along with smaller GM series diesels and some EMD and Cleveland engines as well.

Many years at CAT with mostly high speed until the 3600 came out, and then quite a bit of time with the Mak marine and power gen products.

Maybe if you could be more specific in your question we could get you better answers.

MikeL

I think Cat dumped the MAK engines, and just does parts and such for them now.
One thing I have been sort of studying, is cases of connecting rods being ejected. I have found
some info but its difficult to come by. My reason is something I think I have brought up before,
about cast iron vs steel fab crankcases, especially when it comes to very large size medium speed engines.
I can understand how a fabbed crankcase could be a problem when it comes to welds cracking, cast iron case, properly designed will not have those sort of
problems. But when it comes to a major catastrophic failure where large portions of the crankcase are damaged, fixing cast iron would be prohibitive,
and with very large castings the cost would be catastrophic as well.
I just know if I was in a position to purchase ship engines that size I'd be real concerned about the subject.

Cat very much owns MAK but hasn't rebranded their engine. You can't buy MAK parts from your Cat dealer. Cat will use their local techs to perform repairs on MAK engines under the guidance of MAK.

You are correct that the repairability of fabricated blocks is better than cast. But there are options. Check out these guys, they have an awesome catalog of repairs documented on their website. Pictures included.


The technology to produce cast blocks gets better every day and there are some very large engines using cast blocks including the MTU 8000 series. If you've got the time, this is a great video to watch:
With that said, rod out failures are catastrophic and the resulting crankcase explosions can be deadly. They aren't a common occurrence and we work to prevent them instead of planning around them.

Keep in mind that these engines are insured. The overall costs are more important than incidental costs. Cast engines save customers money overall.

For us in the high-speed world durability no longer seems to matter. We're gearing up to replace 3 year old engines for emissions compliance.

No, CAT has not "dumped" Mak, there are Mak branded products supported by agencies outside of the CAT dealer network, and CAT branded Mak engines in Power Generation and Gas Compression applications. Same thing with Perkins and MWM, CAT branded versions of those engines have CAT model designations and are supported thru the dealer network, there are sales and support networks around the world for these units under their original names. Solar Turbines and EMD engines (as part of Progress Rail) are completely independent of the original CAT dealer sales and support networks.

All current Mak engines are built off cast iron blocks, there were some of the older discontinued models that had fabricated baseframe crankcases.

Above 10,000 to 15,000 bhp gets pretty hard to build a single piece crankcase or block, the casting, machining, assembling and installing get much harder when it gets into those sizes. Many older series engines used fabricated baseframes as low as 1000bhp, but improvements in casting and machining and the cast iron alloys used in the newer engines made them a better choice in many applications. Now when you get into the larger two stroke low speed engines where they start defining BHP output by cylinder (like Sulzer, Mitsubishi, Wartsila, MAN and others in that class), much different how they get built, installed and maintained.

Cast iron blocks get repaired all the time, many with some pretty serious damage, companies like Locknstich, In Place Machining, Marine Diesel Finland and Goltons (and others I'm sure, these are just companies I have worked with in the past) make a pretty good business of it, a lot of times the repairs are done in place without removing the block from the plant or vessel.

Hope that helps, MikeL

Cat and MAK.

Tug I'm very familiar with the locknstitch, that will work in some areas but depends on how bad the damage is.
Strange the cost for those non emission engines are still through the roof.

catserveng
That article explains it.
They are no longer built according to that. Unless things have changed since it was written.

I don't know for sure but I think most all medium speed 4 stroke engines are cast iron frames or blocks now. And some are very large engines.
I wish there was more information on some of the damage to cast blocks of very large engines that have been fixed, and how well it lasted.


As far as I know this is a cast iron frame/block engine, the base or oil pan looks fabricated though.

I suggest touring around the Lock-N-Stitch website. They're very proud of their product and have a great deal of repair examples. Some even have follow-up. In all cases the engines are able to continue operating unrestricted for the remainder of their life.

I think this is one of their more extreme repairs, a cracked crankshaft output flange.

TugboatEng, I don't think there are cast iron crankshafts used in that size engine? That is crazy to think that would hold up, it must have been some alignment issue that caused it? And would not take much to
happen again. On a low stressed member I can see the hook type threads working okay, but on something like that. Its a costly dice game. Awesome that it worked and is supposed still in service.
I'd like to know how it was caught in time?

Cast iron cranks were pretty much a product of the American automotive industry. Cranks are almost always steel otherwise.

I'm guessing that the crack occured in conjunction with another downstream failure. Those Cooper Bessemer engines were very common prime movers for gas compressors.

Or, the failure had another cause such as broken coupling bolts and was discovered along with.

Steel crankshaft, and is why I question that repair for that area. But then an in situ, weld fix would not be easy either. I wonder if others have done this same type of crankshaft repair?
It difficult to believe that it works that well, its not a low stress area like a cast iron water jacket crack.

Welding thick sections like that requires a lot of preheat and there will be distortion. The key to savings is the in-situ repair. For a Cat 3500 series engine, for example, a crankshaft costs around $25k. The labor to replace the crank is over $100k. And that is for a much smaller engine that still has crankshafts available to buy.

enginesrus said:

It difficult to believe that it works that well, its not a low stress area like a cast iron water jacket crack.

Click to expand...

Their process typically results in a component that's actually stronger than it was before the repair.. you're essentially removing a certain volume of cast iron or whatever and replacing it with an equal volume of high tensile strength tool steel.

You earlier asked about crankcase repairs, now you're asking about crankshaft repairs, might be helpful if you could be clear about what you're asking about and what your concerns are.

There are in place repair procedures for crankshaft bearing surfaces, not aware of any currently acceptable field repairs for a crankshaft with cracks going beyond the journal surface.

MikeL.

catserveng said:

You earlier asked about crankcase repairs, now you're asking about crankshaft repairs, might be helpful if you could be clear about what you're asking about and what your concerns are.

There are in place repair procedures for crankshaft bearing surfaces, not aware of any currently acceptable field repairs for a crankshaft with cracks going beyond the journal surface.

MikeL.

Click to expand...

I was mainly just commenting on what you posted. I would like to see LARGE cast iron engine blocks or frames, repaired, that were destroyed by pistons and rods exiting. I would think that if most of the pieces from a block where very small and very numerous, that pinning would be out of the question.
OT I have an old school in place crankpin grinding machine.

A few examples,

Sorry I mixed up catserveng and Tugboat.

Thanks for the links.
In one case they say they laser scanned the area to cast a piece to fit the broken area. Impressive work done and expensive.
If those were weldments the fix is much easier and faster. Fire is an issue too but grinding can cause the same.
Cast iron works, these links were great and much appreciated.