Hi I have this question in my portfolio can someone help me with it please.
Describe in detail the tightening sequenceof the main engine bottom end bolts and explain why this sequence is critical ?
tightening sequence
tightening sequence
Naka
- JK
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Re: tightening sequence
welcome to the Forum and a good question to start off with.
Don't panic, I deleted the double post to keep the info in one place.
There is no need to post in more then one area.
Do you have any thoughts on the question..I'm assuming you are a 1st year student somewhere.
Don't panic, I deleted the double post to keep the info in one place.
There is no need to post in more then one area.
Do you have any thoughts on the question..I'm assuming you are a 1st year student somewhere.
Re: tightening sequence
hi jk
i am on tugs as oow engineer ,as all our overhauls are done in drydock by outside contractors i have never be involved ,only thing i can think to do is check makers manual on maintenance when i am back onboard on duty .
i am on tugs as oow engineer ,as all our overhauls are done in drydock by outside contractors i have never be involved ,only thing i can think to do is check makers manual on maintenance when i am back onboard on duty .
Naka
- The Dieselduck
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Re: tightening sequence
I believe these sequences are to make sure you are not stressing parts. By gradually increasing torque on the bolts, generally in two or three steps, you can be sure that "lop sides" stresses don't develop, and that the bearing shell has the appropriate "crush", at the right places. And that the bolt will remain straight and under uniform stretch.
I can feel a better answer coming from Big Pete, ehehehehe. But its late and I am tired and I see no one else offered up some insight.
I can feel a better answer coming from Big Pete, ehehehehe. But its late and I am tired and I see no one else offered up some insight.
Martin Leduc
Certified Marine Engineer and Webmaster
Martin's Marine Engineering Page
http://www.dieselduck.net
Certified Marine Engineer and Webmaster
Martin's Marine Engineering Page
http://www.dieselduck.net
- JK
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Re: tightening sequence
From the Alco 251F
From Deutzs/BV6/8/9M628 Manual
Tightening Torques:
Tightening Procedure
Followed by hernia, hospital stay, surgery and 6 weeks recovery.
From Deutzs/BV6/8/9M628 Manual
Tightening Torques:
Tightening Procedure
Followed by hernia, hospital stay, surgery and 6 weeks recovery.
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Re: tightening sequence
Hi and welcome to the site,
I think JK's links pretty well cover it.
I would emphasise that as you tighten up you should always keep checking that the BE is still floating freely fore and aft on the crankshaft. I had a Polish 3/E overhauling a generator unit a few years ago, before he started you could bar the engine over with one hand, I came back from the cargo pump room and he and the fitter had got the head on and both of them were jumping up and down with their feet off the deck, and both hands on the turning bar trying to turn the engine!!!! (so that they couls set the valve clearances)
The engine was moving mm by mm and squeaking as it went. It took me half an hour to persuade them that there was something wrong, they kept insisting that now everything was good because they had fitted new bearings. When I eventually got them to strip down the unit we found a big lump of the old bearing metal adhering to the crankshaft, the new bearing shells had clamped on to it like a brake.
BP
I think JK's links pretty well cover it.
I would emphasise that as you tighten up you should always keep checking that the BE is still floating freely fore and aft on the crankshaft. I had a Polish 3/E overhauling a generator unit a few years ago, before he started you could bar the engine over with one hand, I came back from the cargo pump room and he and the fitter had got the head on and both of them were jumping up and down with their feet off the deck, and both hands on the turning bar trying to turn the engine!!!! (so that they couls set the valve clearances)
The engine was moving mm by mm and squeaking as it went. It took me half an hour to persuade them that there was something wrong, they kept insisting that now everything was good because they had fitted new bearings. When I eventually got them to strip down the unit we found a big lump of the old bearing metal adhering to the crankshaft, the new bearing shells had clamped on to it like a brake.
BP
It is always better to ask a stupid question than to do a stupid thing.
Re: tightening sequence
I had an identical occurrence to the one that Big Pete mentioned except not so obvious to figure out. Turns out that on this older model generator engine all bearing sets have the same part number, even if they are undersized. A new undersized bearing was fitted by mistake, whenver the big end bolts were loose the engine would bar over no problem but when the bolts were torqued down it would jam tight. To make matters worse, taking the bearing out for inspection showed no abnormalities and the Babbitt metal seemed fine, re-install the bearing and try again same problem. After three tries measured the new bearings and compared with the old ones, the bearing was smaller in diameter by just about the amount of clearance that should be present.