Biggest Reciprocating Engines


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Alex McLean

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Hey everyone,
In so many places, such as books, movies and documentaries, many have said that the reciprocating engines on Titanic were the biggest ever built. When they say this, do they mean biggest to that time, or biggest, full stop.
Also, were Britannic or Olympic's the same size, or bigger/smaller?

Thanks!
Alex
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Jeremy Lee

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Jun 12, 2003
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Horsepower? The Mauretania and the Lusitania's engines were more powerful than the Titanic and the Olympic. I am not too sure for the Britannic.
 

Dave Gittins

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Mar 16, 2000
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Alex, I think it's safe to say that the engines on the Olympic class were the biggest of their kind ever to go to sea. That is, they were the biggest triple expansion engines ever used. I don't seem to have the all numbers handy, but the two low pressure cylinders were 96" in diameter.

Some of the quadruple expansion engines might have been in the same ballpark. Kaiserin Auguste Victoria had a quadruple expansion engine with a fourth cylinder 106" in diameter.

I stand to be corrected, but I'm pretty sure Britannic's engines were the same as those of her sisters.
 
Jan 5, 2001
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Hi!

I stand to be corrected, but I'm pretty sure Britannic's engines were the same as those of her sisters.

Strictly speaking, they were the same kind of size, but 'hot-rodded' a little. A number of subtle changes were made. This has been explored in detail in 'The Finer Points of Ship Construction.'

Best regards,

Mark.
 
Dec 29, 2000
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Is this only for marine engines, or do you also include in your comparement steam engines mounted at land?
Because I think then there were much larger engines, but in ship, well those were very large engines, but in those times all was little bigger, so there seems to me many steam engines play in the same legue, as mentioned before.
So big is not allways big, because we must define, what big means, because in horsepower, well, there maybe other which were bigger, in size, okay, maybe one of the biggest, in power at crankshaft, well, and so on....
Because there was after this a very rapid change in reciprocating steam engines: Smaller, faster in RPM, less steam-consuming, more effectiv. And all was abondoned by development of Steam turbines and afterleast by the development of diesel engines, or in naval technologies by gas turbines.
But as mentioned by me before: Steam engines still today can compete with diesel, if you only let and do not basis upon old machinery books.
See http://www.dlm-ag.ch/prospekte/modern_steam.pdf for reference, even if this is only for great lakes ships, but sea-ships got often more available space...
so here the change is more visible, because those modern engines are smaller and turn much faster.
These 'fast-runners' were smaller in size than the big 'slow-runner' but have 'slow runners' have much more torque at the crankshaft, because of larger cranks. So from that point, well, we can consider Titanics engines as one of the biggest ever build!
And even for those times it was one of the modernest engines build, less coal needing, with a very fine engine power adujustability, and a very good performance with the after switched lp turbine and condensator. So the engine is not only from the size impressive, it is also from technical very impressive, because affter Titanic less changes were done, to ensure better reciprocation engine performance....
 

Dave Gittins

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For the record, the cylinders on the Olympic class ships were 52", 84" and 97". The stroke was 75".

When I can, I'll check out a few of the big quadruple expansion engines.
 
Dec 29, 2000
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Well, to consider: 97" are nearly 2,5 Meters, and I thought Titanic, as even Olympic got two LP Cylinders of same diameter, so there were two of this gigantic cylinders! Not even easy to imagine how big that is!
And we should remind: Bigger is a thing big mechanical difficulties, because the piston itself we can think of it as a large iron disk, just hold by the large iron bar in the middle. So the pressure of the steam pí¼ushed down to that disk to bring it in motion, near the piston middle at the bearing the disk of the piston surface won't bend under the huge force, but close to the cylinder walls the disk will bend, making much trouble to avoid scratching the stroke tubes or breaking the seal rings outside the piston disk. Also if the piston moves, the will because of bending of the surface and of the mass in motion be critical forces to the material, also a vibration of the piston disk is to expect, in such large ones the vibration can have dramatical effects on bearings, holds and as well the smooth an soft run of the whole engine. So we can consider Titanics engines are great masterpiece of machinery art! Because large cylinders like this are realy not easy to construct, and require top quality in development, made and set together terms, a slight mismatch, a slight failure in material, or even an slight difference in mass could make the whole engine struck, and the force of the high masses in motion might bend the cranks, rods and bars or complete destroy the whole machinery, this is considerable same dramatic as a boiler explosion. So for those guys who constructed this engine, there is a very deep respect.
Consider only the dramatic force of the steam pressure, for example: The force of 20 bar Steam pressure to a piston of 24 inch diameter cylinder will be at more then 38 tons!
 
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robert s hauser

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I remember reading somewhere that Britanic was fitted with a larger turbine engine than the other 2 sisters, and that, at 19,000hp, it was the largest marine steam turbine ever constructed.
 
Dec 29, 2000
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I guess bigger Turbines will be no advantage! Because turbines were only good, if running an a little range of rounds. So they are realy not good for ships as the only main engine, except military usage.
So the larges steam turbine tankers use the turbine only for traveling at march speed, but not for docking actions, for this purpose many of these ships have auxillary diesel engines or a smaller steam turbine with a fluid gear attached, to adapt shaft speeds to the demand and make quick changes possible.
correct me if this is not true, but I guess to remember this, as I visitied our power plant turbine builder, who also had knowledge in building ships turbines...
 
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Lajos Berínyi

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Hello guys!
I have a question: The measurement of the engines were inside numbers? Or outside diameters?
 
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