# 7 cylinder diesels



## Derek Dunn

Hi, when I sat my "Orals" the examiner asked what I would find peculiar within the crankcase of a 7 cylinder engine. I didn't know the answer but made remarks about firing orders etc. To this day I don't know the definitive answer. Two weeks ago I was in Northern Portugal and there is an old hospital ship - now a museum, and she is fitted with 2 Fairbanks Morse 7 cylinder 2 strokes with scavenge pumps. This question about the 7 cylinder engine came back.
Can anybody help?


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## makko

I have sailed with 7-Cyl engines and nothing comes to mind! I just checked my "Diesel Engines: Q&A" by A.J. Wharton and found no mention. Maybe the examiner just wanted to unsettle you.
Rgds.
Dave


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## borderreiver

The 10 older boarder boats had 7cl but they come in a unit of three then four.
The shaft was joined between by a piece called a donkey leg could this be the object you are looking for


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## Satanic Mechanic

it might be A Torsional Vibration Damper - 

Pretty much a standard fixture nowadays to most engines but 7+ cyl engines had a rep for torsional vibrations and were often equiped with one as standard.


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## Duncan112

Thinking about TV dampers - did engines with an odd number of cylinders have two chain driven Lanchester types?


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## Satanic Mechanic

Duncan112 said:


> Thinking about TV dampers - did engines with an odd number of cylinders have two chain driven Lanchester types?


Yup but they were more for second order and non sinusoidal piston vibrations. They are offset weights running at 2 x engine speed


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## MARINEJOCKY

7 KZ MAN very perculiar not to have engineers inside that crank case at every port.


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## Duncan112

Satanic Mechanic said:


> Yup but they were more for second order and non sinusoidal piston vibrations. They are offset weights running at 2 x engine speed


Yes, but I was used to seeing one only fitted to 6 cylinder engines, went on a 9 cylinder KFF job and there were 2 fitted, one at each end of the crankcase, then sailed with newer MC engines that just had an axial damper.

Whilst trying to find a drawing on the net I came across this - bearing in mind the price of the real thing some may be interested

ftp://195.214.211.1/books/DVD-031/W...nd_Gas_Turbines_(2004)(8th_ed.)(en)(884s).pdf

Enjoy


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## Derek Roger

The answere I think is that they had a torsional vibration damper at the forward end of the engine . However one would not see this piece of kit when in the crankcase .
Perhaps the examiner had too many pints at lunch .


Other than that I am at a loss . Derek


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## Basil

> I was used to seeing one only fitted to 6 cylinder engines


I thought 6 cyl engines were naturally balanced - no?


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## makko

Derek Roger said:


> The answere I think is that they had a torsional vibration damper at the forward end of the engine . However one would not see this piece of kit when in the crankcase .
> Perhaps the examiner had too many pints at lunch .
> 
> 
> Other than that I am at a loss . Derek


Agreed Derek, exactly my line of thought. The damper mechanism is independent of the crankcase.
Rgds.
Dave


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## Satanic Mechanic

Yeah its one of those ones isn't it!!, its not really in the crankcase more attached to the end but it is attached to the crank which means the crank extends beyond the end of the crankcase.

If it is the answer then the examiner was trying to be cute, cant think of anything else though


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## JoK

I sailed on a ship with two 7 cylinder Cooper Bessemer. The things vibrated so bad that nothing would stay tight on them, they spurted oil and diesel like a artery had let go. They had a dead spot and if the engine stopped there, they wouldn't start, you had to rig a chainfall and hook onto a coupling bolt to turn it. More then one Captain come to grief while docking that ship, one fellow cleaned all the brand new crib work off of the front of the wharf when it didn't go astern.
The engine rep walked onboard one day, looked at the engine and said, we don't make 7 cylinders! Apparently to met the spec, they just chopped off the last cylinder on the block.
With all that, I have no idea what the examiner figured would be in the crankcase.


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## Basil

> The things vibrated so bad . . . . said, we don't make 7 cylinders! . . . . I have no idea what the examiner figured would be in the crankcase.


Well there you are - it was the #7 Good Luck Fairy; but yours had escaped via an unguarded crankcase door (Jester)


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## Derek Dunn

Well guys, thank you very much for some very interesting feed-back, it is very much appreciated. 
On reflection, I tend to go with the idea that the examiner wanted to find out what I DIDN'T know rather than what I did and wanted to here my brain working, it doesn't do that very much nowadays.

One last question to you all ---- how were the cranks arranged? As you all know 7 doesn't divide into 360 or 720 degrees. Were there two cylinders on TDC at the same time or were they spaced at 51.4 degrees and 102.85 degrees.


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## Satanic Mechanic

I have only ever seen them evenly spaced


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## eldersuk

Possibly something to do with crank web balance weights? Although off the cuff I can't think what.

Derek


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## chadburn

Your right eldersuk, the crank web balance or bob weight's were of course bolted on and needed to be checked for tightness on a regular basis.


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## jim garnett

Derek Dunn said:


> Well guys, thank you very much for some very interesting feed-back, it is very much appreciated.
> On reflection, I tend to go with the idea that the examiner wanted to find out what I DIDN'T know rather than what I did and wanted to here my brain working, it doesn't do that very much nowadays.
> 
> One last question to you all ---- how were the cranks arranged? As you all know 7 doesn't divide into 360 or 720 degrees. Were there two cylinders on TDC at the same time or were they spaced at 51.4 degrees and 102.85 degrees.


The number of degrees in a circle is.only a standard in the british units.Metric divides a circle into radians.where the length of the arc is the same as the radius and is equivalent to 57.296 degrees.A circle can be divided into an infinite number of parts and can thus be divided into any fraction we require. Your standard protractor would be of little use ,but it can be done. jim garnett


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## jim garnett

makko said:


> Agreed Derek, exactly my line of thought. The damper mechanism is independent of the crankcase.
> Rgds.
> Dave


In my day the were known as the Bibby detuner and were fitted forrard of the crank case.One section was fitted to the crank and the other ran freely on the crank .they were connected to each other by heavy springs.They were fitted I thought to most engines regardless of the number of cylinders.
Jim Garnett


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## eldersuk

This is starting to get on my nerves....

Would a seven cyl engine be the shortest engine with the crankshaft in two parts with a coupling? Except for some Doxfords I can't think of a shorter engine with a coupling.

Derek


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## Satanic Mechanic

eldersuk said:


> This is starting to get on my nerves....
> 
> Would a seven cyl engine be the shortest engine with the crankshaft in two parts with a coupling? Except for some Doxfords I can't think of a shorter engine with a coupling.
> 
> Derek


I am quite sure that there have been numerous variations over the years but modern 7 cyl inder engines do not have split crankshafts.

They don't have web balance weights either - in fact very few slow speed diesels do these days


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## Abbeywood.

Satanic Mechanic said:


> I am quite sure that there have been numerous variations over the years but modern 7 cyl inder engines do not have split crankshafts.
> 
> They don't have web balance weights either - in fact very few slow speed diesels do these days


Depends on the engine size.
Most medium-, and high speed diesels are solid crankshafts irrespective of the number of cylinders, whereas slow speed engines are built in units of three, four, and five cylinders and assembled from those multiples although some six cylinder engines have solid crankshafts. (See an earlier thread in reference to Sulzers, which were constructed in maximum five cyl's and assembled at the licensees engine workshops as required. This apparently so that Swiss-built engines,(Winterthur), could be manoeuvred through the railway tunnels and five was the maximum size permissible, and hence the narrow width of Sulzers when compared with other types.


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## chadburn

Bear in mind Derek was "double barrelled" pre 1982 and the Examiner would be referring to a engine built before CAD-CAM.


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## Derek Dunn

MARINEJOCKY said:


> 7 KZ MAN very perculiar not to have engineers inside that crank case at every port.


Nice one!


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## TIM HUDSON

borderreiver said:


> The 10 older boarder boats had 7cl but they come in a unit of three then four.
> The shaft was joined between by a piece called a donkey leg could this be the object you are looking for


Chris.
Old border boats were 6 clyinder engines.
rgds


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## Satanic Mechanic

Abbeywood. said:


> Depends on the engine size.
> Most medium-, and high speed diesels are solid crankshafts irrespective of the number of cylinders, whereas slow speed engines are built in units of three, four, and five cylinders and assembled from those multiples although some six cylinder engines have solid crankshafts. (See an earlier thread in reference to Sulzers, which were constructed in maximum five cyl's and assembled at the licensees engine workshops as required. This apparently so that Swiss-built engines,(Winterthur), could be manoeuvred through the railway tunnels and five was the maximum size permissible, and hence the narrow width of Sulzers when compared with other types.


Modern crankshafts are invariably semi -built with the crankpin and webs being a single forging shrunk fitted onto the the main pins after machining. There are anumber of reasons for splitting a shaft but the normal maximum size of single shaft is 7 in my experience. 

y and by if anyone should ever want to see this all happening on a single site can I highly recommend HHI in Ulsan (a veritable modern industrial wonder of the world)


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## Nigel Wing

While serving on P&O gas carriers, there were 4 ships in the fleet. German built (known as the Big G's) Garinda. Galpara. Galconda, Garala. These ships Main Engines were MAN 7 cylinder - on board each was a vibration damper mounted aft in the steering gear flat, developed as rumour had it by AEG-SCHENK for these particular vessels, when it was operational, which was rarely, it would reduce hull vibrations, it never operated while I was aboard Garinda, and at sea the accommodation would shake noticeably in a forward and aft motion.
It required much skill to maintain and operate, the company sent several of us to the AEG facility in Hamburg for training, but if truth be known, it was rather too technical for even the brightest of electricians.
Cheers
Nigel.


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## ccurtis1

TIM HUDSON said:


> Chris.
> Old border boats were 6 clyinder engines.
> rgds


were the afghanistan and kurdistan not 7 cylinder sulzer rnd 76's Tim, or is my memory playing up. If they were, perhaps thats what Chris was thinking about


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## TIM HUDSON

ccurtis1 said:


> were the afghanistan and kurdistan not 7 cylinder sulzer rnd 76's Tim, or is my memory playing up. If they were, perhaps thats what Chris was thinking about


I sailed on Strait of Canso and to best of recollection she was a 6RND engine.Was she not same as above mentioned ships ?
rgds


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## TIM HUDSON

TIM HUDSON said:


> I sailed on Strait of Canso and to best of recollection she was a 6RND engine.Was she not same as above mentioned ships ?
> rgds


whoops, sorry. Just checked the Common Bros history "The Trades Increase" and you are correct the Strait of Canso class from Redheads were 7 cylinder Barclay Curle engines.


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## stoker

*Man 7 Kz*



MARINEJOCKY said:


> 7 KZ MAN very perculiar not to have engineers inside that crank case at every port.


Inside that rotten three part liner too!


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## jmirvine

Sailed on 2 ships with 7 cyl Sulzer's and they were both absolute rubbish. Once the main engine was started, you couldn't see the other end of the engine room for blue smoke! Used to burn out pistons, and crack liners with monotonus regularity. Half the time we used to say that we were running on about 3 and a half cylinders.

Worst ships I was ever on !


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## David Campbell

*7 cylinder Sulzer RND*



jmirvine said:


> Sailed on 2 ships with 7 cyl Sulzer's and they were both absolute rubbish. Once the main engine was started, you couldn't see the other end of the engine room for blue smoke! Used to burn out pistons, and crack liners with monotonus regularity. Half the time we used to say that we were running on about 3 and a half cylinders.
> 
> Worst ships I was ever on !


Sailed as chief engineer on "Iron Shortland" 1988-93, the best engine and ship ever. The main engine was a 7 cylinder Sulzer 7RND built by IHI Kure, 23,450 bhp


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## Noel Martin

The Medic & Megantic Shaw Savill lines both had twin screws with 2 x 7 cylinder engines British built B & W engines of about early 60s manufacture ran okay on the trip to Aussie & back. That was in 1967 and we were the first ship diverted around the Cape of Good Hope during the Suez crisis. 27 days without bunkering. Fremantle to Las Palmas. Other ships on the same run stuck in the canal for about 5 to 7 years.


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## paulm

*7 Cyl Question*

Gentlemen,
I have given a lot of thought to the original question posed in this thread. 
Like all previous contributors nothing comes to mind in a 7 cyl engine c/case that one wouldn't see in another configuration .
As to the disposition of the examiner one can only speculate but liquid lunches were not unknown in those days. (Pint)
Paulm.


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## Duncan112

Playing the devil's advocate, there is always the possibility that the candidate that was up immediately before let slip something that the examiner had not previously heard of (or misunderstood) and the examiner, having understudied Torquemada decided to ask the next contender and see what he made of it?


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## Noel Martin

Just come up with this formula today. Harland & Woolf engines 7 cylinders crank sequence (ahead) 1.7.2.5.4.3.6. angle between cranks 51.43 (degrees) B & W single acting engine Medic & Megantic Shaw Savill Lines. CC Pounder Marine Diesel Engines.


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## Derek Dunn

Thank you Noel, it would seem that you have answered all the questions about this configuration. It all goes back to the fact the examiner was trying to catch me out.(Applause)


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## Derek Roger

Derek Dunn said:


> Thank you Noel, it would seem that you have answered all the questions about this configuration. It all goes back to the fact the examiner was trying to catch me out.(Applause)


Back to your original post Derek " what you find ( odd ) I cant spell peculier etc.

Examiner was having a bit of fun at your expense ' I trust you passed .
I used to to have a Ford V8 which seemed to missfire from time to time ; I suppose that made it a 7 Cyl ; that was odd .


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## Derek Dunn

We had a lot of fun with this one but I think it is now closed.
Thanks to all for subscribing.


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## Mike Ross

Hello Derek,
My name is Michael Ross and I am replying to your query about 7cyl. diesels. I once did a coastal voyage on a coastal type ship built in 1947. This was to be her last voyage before going to the knackers yard. She was powered by a 9cyl. British Polar engine and attached to the forward end was a huge (like another cyl.) air compressor. If you looked in the crankcase, which I did, you would see this was no cross-head engine but a two-stroke trunk engine. When we sailed there was a moderate swell running but enough to make the engine race before the governor caught it at which time it made a terrible bang, bang banging noise. Frightened the pants off me. The other engineers assured me that it was nothing to worry about as it always did this.
When I first met the captain he told me I had a lot of drinking to do as the last C/E never drank. He used to sit with his rear end on the chart table and steer with his bare feet some-how wrapping his toes around the spokes of the huge wooden wheel. It was a long time ago and I was only there for about three weeks so don't remember to much. Hope this helps. Cheers Mike.


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## daveyw

Nigel Wing said:


> While serving on P&O gas carriers, there were 4 ships in the fleet. German built (known as the Big G's) Garinda. Galpara. Galconda, Garala. These ships Main Engines were MAN 7 cylinder - on board each was a vibration damper mounted aft in the steering gear flat, developed as rumour had it by AEG-SCHENK for these particular vessels, when it was operational, which was rarely, it would reduce hull vibrations, it never operated while I was aboard Garinda, and at sea the accommodation would shake noticeably in a forward and aft motion.
> It required much skill to maintain and operate, the company sent several of us to the AEG facility in Hamburg for training, but if truth be known, it was rather too technical for even the brightest of electricians.
> Cheers
> Nigel.


Yes I remember the schenk gear. We always ran it on galconda over a certain revs, except when I forgot to start it!


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## Tim Gibbs

daveyw said:


> Yes I remember the schenk gear. We always ran it on galconda over a certain revs, except when I forgot to start it!


Probably had more to do with propeller excited vibs that engine torsionals.


Derek Dunn said:


> We had a lot of fun with this one but I think it is now closed.
> Thanks to all for subscribing.


Never start something you can't stop?


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## Tim Gibbs

daveyw said:


> Yes I remember the schenk gear. We always ran it on galconda over a certain revs, except when I forgot to start it!


Probably not torsionals but prop exited vibs.
Often possible to fix torsionals by changing crank angles. Was involved with a pair of 8 cylinder 2- stroke MANs and they made the crank angles 42.5 - 47.5 - 42.5......... degrees to magic them away. On this particular vessel there were concerns about prop exited vibs so they had a very clever bit of kit to synchronise the two engines with both No.1 cylinders firing simultaneously and then the ability to vary the angle between the two by up to 40 degrees to get the vibs from one prop to cancel out the vibs from the other. Have no idea if it worked ......... there were no prop excited vibs to cancel. An example of a very clever solution to a problem that didn't exist


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