[BERRIET]

Good morning everyone ,

did anyone deal with two stroke , double acting MAN diesel engines? D 8 Z 72/120 type ? with roots blowers ?

thanks for any infos !!

[steve2]

Similar to the H&W-B&W double actors. The roots blowers were chain driven from the crankshaft. Lots of air used when manoevering from ahead to astern and a great thump when the flap valves in the blowers went across. Reversing the engine also reversed the blowers so the flap valves corrected the flow of scavenge back to the engine.
Wonderful watching these engines in operation, pistons flying everywhere as the upper exhaust pistons were yoked to the lower. When overhauling a unit the top platform was a mess of gear.
Most engines had conventional camshafts, fuel pumps and fuel injectors but some had gas pumps and injectors. (but that's another bag of worms)
Best regards
Steve2

[Blackal]

Were the H&W engines not "Exhaust Piston" type, rather than true "double-acting"? I seem to remember them as having the exhaust piston coupled to the crankshaft via a crosshead and eccentric, rather than a crank.

Al

[steve2]

Hi Al,
In the H&W engine the lower exhaust piston was strapped to the upper exhaust piston via yokes and driven by excentrics as you say. The main piston between them was driven by the crank. So as there were fuel injectors in the upper and lower compression spaces this made them double actors. Hope I'm making sense!
Best Regards, Steve.

[cubpilot]

Steve, if i understand you the engine had 3 pistons? if so with the bottom being coupled in some way to the top did this lower piston have the main piston rod passing through it and some form of stuffing box?

I once sailed on an MAN engined ship built immediately after ww2 in denmark. it was loop scavenge with side rods from the crossheads driving scavenge air pumps and also utilised the under piston method with flap valves to increase scavenge air pressure. all very normal but the bug bear with the engine were the stuffing boxes on the piston rods. on each rod there was a main set located at the bottom of the cylinder liner to seal against the scavenge pressure and then a smaller set on the crankcase top to seal the crankcase. the gap between was exposed and you could see the piston rod moving up and down.
the stuffing box rings were cast iron segments and were size matched to the rod diameter. regularly we would get siezed rings and then if the engine was not slowed down promptly the fuel pump on the affected cylinder lifted and liberal quantities of oil squirted onto the rod then in short time the rod would start to build up heat and could become cherry red. highly conducive to a crankcase explosion. if a rod did go red it would also bend. in that case we would end up with a major stoppage and change pistons. the ship carried more than the normal stock of spare piston rods and we became quite adept at rebuilding piston assemblies whilst at sea.

i bet those H&W engines were a nightmare

[Archie NS]

There's a good description of a Harland & Wolff opposed piston double acting engine by C.C. Pounder. Lots of drawings.

http://www.rakaia.co.uk/downloads/hw-da-engines.pdf

I never sailed on a double acting H&W but plenty of opposed piston ones, somewhere in the far past I was told that the reason H&W went with the eccentrics was due to a patent dispute with Doxfords. This may be a myth I'm not sure

[sidsal]

Fascinated by you engineer wizards. I was 3rd mate on a tanker F J WOLFE of the Anglo American Oil Co just after ww2. She had twin MAN engines which were rogue engines in all senses of the word. The engineers kept watch in swiming trunks due to the oil squirting everywhere. Most places we called at we stayed a week at least whilst they tinkered with the engines. There have been quite a few Threads about her recently. I joined her in Barrow for 3 months where she had gone as engineers from the MAN works were working there on peroxide propulsion for submarines ( superceded by atomic power). She was just as bad after their attentions. She had sister ships with similar problems and once we rowed over piston rings to one of them in the Arabian Sea where she was wallowing.
Incidentally our Rotary visited a most intersting engine museum at Poynton Cheshire - the Anson Museum. It is on an old colliery site and has lots of old engines which are in working condition. As you chaps probably know, Manchester had about 6 engine builders ) Mirlees, Gardener, Crossley and so forth. Sadly all now gone.
Best wishes
PS Mirlees was taken over by MAN a few years ago - and shut down except for a department maintaining Mirlees engines. The main factory is demolished and office blocks just built there ( all empty of course). Paradoxically, someone told me that they make more money now than they did when building engines. It's a crazy world.
Sid

[steve2]

G'morning Cubpilot.
Yep- the piston rod for the main piston passed through a stuffing box in the centre of the lower exhaust piston and also through the entablature above the crankcase. The lower exhaust piston had a yoke from which rods went up to the upper exhaust piston, driving it in tandem. Lots to watch on those old engine rooms. There was no underpiston scavageing as this was provided by rooted blowers. As Archie points out- CC Pounder wrote the bible! Unfortunately most of us dummped our copies when the dinosaurs died out!
Sid- Liverpool Nautical mueseum also has a latge collection of working models of various engines built to fit into local built ships. Camel-Lairds even built an engine called the Fulgar(?) Engine where the main piston of one unit drove the exhaust piston of the next. Talk about man's inhumanity to man! I believe that this engine was nicknamed the fullofgear engine.
All the best for the New Year. Steve

[david freeman]

Originally Posted by BERRIET

Good morning everyone ,

did anyone deal with two stroke , double acting MAN diesel engines? D 8 Z 72/120 type ? with roots blowers ?

thanks for any infos !!

Question Were Gotoverken Engines ever produced as a double acting version, if so they must have been quite a joy?

[cubpilot]

I like the comment that it was a simple engine to overhaul.
i forgot to mention that on that 1946 built MAN if the ship was loaded evenly we had no problem but if any hogging sagging or twist in the hull then we suffered. luckily average passage length was a week and i suspect on a bad passage there were words from the chief to captain.
my other MAN engine experiences on mid 70s built engines were a delight. in 5 years i think we only had one stoppage due to an engine problem when a cam profile broke.

[BOB.WHITTAKER]

My first ever ship was MV Salamanca , one of PSNC "S" boats,I joined it in Hull whilst she was in drydock. All of the S boats had 8 cylinder double acting B + W main engines,I couldnt believe my eyes the first time I saw the engine run,did a few runs round the land then deep sea on the Somers Isle,she had a 4 cylinder single acting B + W. Then back onto the Salamanca as 4th engineer, the only highlights really were the occasional scavenge fire, the engine though labour intensive(24 pistons,numerous fuel valves, air start valves,relief valves and stuffing boxes) did to my memory anyway seem reasonably reliable.I seem to recall spending more time gassing up the deck fridge containers under the Chiefs (George Hawkins) instruction than anything else .

[tugtere]

I did a stretch on Nauru Island in the power house in the 1980's. There were two Mirlees, two Fulagar's and a pair of "Crossley-Pielsticks" installed.I was supposed to dismantle the Fulagars for scrap but the new Crossleys were so unreliable(from brand new) that the old girls were retained as standbys.They are probably still there now.They were an amazing thing to watch with bits n pieces jumping up and down.Regards Ray

[Philthechill]

I doubt if there's anyone old enough on SN to have sailed on White Star's "Brittanic" but I believe her, and her sister-ship ("Olympic"?) had double-acting FOUR strokes!

I'm sure I've seen a picture of one of these engines, somewhere, but I'm not 100% certain.

I seem to remember looking at the forest of push-rods and thinking what a nightmare they must have been for maintenance.

Can anyone confirm whether I'm right---------------or is it time to call for "the-men-in-white-coats"? Salaams, Phil

[BOB.WHITTAKER]

Double acting fourstrokes ,I never sailed on one but " I know a man that did ". In the late sixties and into the seventies Houlder Brothers had a group of stalwarts who used to cover most of the relieving duties in the U.K. Three of the engineers were Alex (the Silver Fox), Ronnie Angel and Alec Cowderoy . Many a long "smoko" in the duty mess (whilst alongside) was spent with Alec in particular regaling all present with his tales of past engines.He could go back to prewar days and he gave vivid descriptions of sailing on double acting fourstrokes regards the maintenance levels and also their function, allways interesting was his explanation of the mechanisms involved in getting the engine to run astern. These sessions were as informative as any of the E.K. lectures when I did 2nds and Chiefs at South Shields .

[chadburn]

Not as yet for the white coat's Phil, these engine's were built by B&W. It was considered to be a very important development of the marine diesel, a single cylinder engine was built at their experimental station at Christianshavn which gave a reading of 1,000BHP, it ran day and night for a month and B&W were highly delighted with it. It was of course all to do with poweeeeeeeeeeer. Up till this engine appeared B&W max was 300 BHP per Cylinder, the reason for the building of the double acting for was for the fast Liner market which meant that large fast Liner's could be built with twin engine's at that time without the normal distribution of shaft's and prop's with other forms of propulsion. Never worked on one a bit before my time, I thought Doxford's had way to many extra bits hanging about never mind this engine!!!

[Philthechill]

First things first, then the nitty-gritty!

Thanks Bob and Geordie Chief for saving me from spending the rest of my days doubting my sanity (however, come to think of it, I do that on a daily basis anyhow!!!).

I said that I thought the ship, with the double-acting four-stroke engines was "Brittanic". I was wrong as she actually had a combination of up-and-downers and turbines.


I found-out, from t'Internet, ( Pounders 8th. Edition), that there were two ships fitted with the B&W four-strokes and they were the Swedish America "Gripsholm", (1925-built), and Union-Castle's "Caernarvon Castle" of 1926. (Incidentally there's very little to be found-out, even from said Internet, about these engines, although having just typed that, I never looked on B&W's site (if they have one) to see if they have a historical section. Memo to self:- Your next task, after submitting this, is to check for a B&W site!!!!).

Now, being as "Caernarvon Castle" wasn't scrapped until 1963 surely there's someone who sailed on her, (who is on this wonderful site), can give us a bit of an insight as to what these engines were like to work on?

Or was the ship re-engined at some time?

Thanks, again, Bob and Geordie Chief. Salaams, Phil

[surfaceblow]

There is an article on B & W Number 1 at Christianshavn with pictures at the link below. One of the other Dieselfacts is a short movie on the first Diesel Ship I forget which issue but you can have an interesting time looking at the new and old stuff in most issues.

http://www.manbw.com/files/news/file...cts_2007_1.pdf

Joe

[hamishb]

Originally Posted by Philthechill

First things first, then the nitty-gritty!

Thanks Bob and Geordie Chief for saving me from spending the rest of my days doubting my sanity (however, come to think of it, I do that on a daily basis anyhow!!!).

I said that I thought the ship, with the double-acting four-stroke engines was "Brittanic". I was wrong as she actually had a combination of up-and-downers and turbines.


I found-out, from t'Internet, ( Pounders 8th. Edition), that there were two ships fitted with the B&W four-strokes and they were the Swedish America "Gripsholm", (1925-built), and Union-Castle's "Caernarvon Castle" of 1926. (Incidentally there's very little to be found-out, even from said Internet, about these engines, although having just typed that, I never looked on B&W's site (if they have one) to see if they have a historical section. Memo to self:- Your next task, after submitting this, is to check for a B&W site!!!!).

Now, being as "Caernarvon Castle" wasn't scrapped until 1963 surely there's someone who sailed on her, (who is on this wonderful site), can give us a bit of an insight as to what these engines were like to work on?

Or was the ship re-engined at some time?

Thanks, again, Bob and Geordie Chief. Salaams, Phil

Hi Phil, A picture of the Double Acting 4 stroke engines built by Kincaids in the 1920s. The photo shows the dreaded blast compressors on the end of the engine. Quite a lot of these were built, must have been a nightmare to maintain. As an apprentice I worked on spare pistons cylinder covers and other bits for these engines in the 1950s.
Regards
Hamish

[chadburn]

The thumbnail picture by Hamish is about the same profile as the single cylinder 1923 test engine, unfortunatly I have changed to Vista and I am having difficulties posting photo's as the system will not accept my server for some reason otherwise I would have posted the photo I have from the old B&W house mags which I received when I worked for Maritime O. The companies engine's were mainly B&W and the companies Senior Engineer's were on the mailing list.

[Long gone]

I have a book in my possession, 'British Ships Illustrated' by A.C. Hardy, published in 1933. The 1929(?) 'Georgic' and 'Britannic' are described.

It says she has 'twin screws each driven by a large Harland-B&W 4-cycle double acting internal combustion engine, each developing about 10,000 horsepower, and the two of them giving the ship at sea a speed of about 18 knots'....Later on it says 'each engine has 10 double-acting cylinders' It doesn't say whether these were O.P. though.

As an aside, The White Star Line seems to have been quite an innovator when it came to engine design, the engine spec. on the previous 'Britannic' being a case in point; the first ships to use an L.P. exhaust turbine in combination with recip. engines.

[chadburn]

It is also indicates that the new engine may also be built as a long stroke engine for a single screw ship, this being a substitute for the twin screw config on larger cargo and passenger vessel's which may have been formerly provided with B&W short stroke engines with a similiar economy being secured. The new type can be built with power in the region of 5,0000/6,000bhp

[Philthechill]

Originally Posted by hamishb

Hi Phil, A picture of the Double Acting 4 stroke engines built by Kincaids in the 1920s. The photo shows the dreaded blast compressors on the end of the engine. Quite a lot of these were built, must have been a nightmare to maintain. As an apprentice I worked on spare pistons cylinder covers and other bits for these engines in the 1950s.
Regards
Hamish

Hamish! Thanks very much for putting this picture of the, Kincaid-built engine, on here but I'd already "clocked" the picture in The Gallery and added a couple of comments about it. Salaams, Phil

[hamishb]

Originally Posted by Philthechill

Hamish! Thanks very much for putting this picture of the, Kincaid-built engine, on here but I'd already "clocked" the picture in The Gallery and added a couple of comments about it. Salaams, Phil

Hi Phill, I have posted a picture of a side view of an engine built for Clan Line.
Kincaid built engines, with a few exceptions were built on a B&W sub lisencs from Harland & Wolf.
The 3 camshafts are visible along with the upper pushrods.
I will scan and post a picture of a Single Acting engine of the same era for comparison.

[hamishb]

Hi Phill, there are enough pictures and some other inieresting info. in the gallery under Clan MacDonald so I won't add another picture.
Single acting engine is in.
Regards
Hamish.

[Philthechill]

Originally Posted by hamishb

Hi Phill, I have posted a picture of a side view of an engine built for Clan Line.
Kincaid built engines, with a few exceptions were built on a B&W sub lisencs from Harland & Wolf.
The 3 camshafts are visible along with the upper pushrods.
I will scan and post a picture of a Single Acting engine of the same era for comparison.

Going astern with such an engine must have been quite an undertaking I would imagine!

The maintenance of a double-acting four-stroke must have been a nightmare what with the numbers of valves to look after! I bet the engineers couldn't believe their luck when double-acting two-strokes became the order-of-the-day. Thanks again Hamish. Salaams, Phil