Miniature engines, anyone? Enjoy! These engines are truly awesome!
Harold
Miniature engines, anyone? Enjoy! These engines are truly awesome!
Harold
Blimey!
How do they then install it in a ship? Sodding great winch?!?!
I'd have thought something like that would be made as bits, then assembled in the hull of the ship, then the roof of the engine room built, then the rest of the ship built on top...
Pity there isn't a picture of the spark plugs...
ABS
That was just the test assembly. They will take it apart and rebuild it on the keel as the ship is being built around it.
It's a diesel. No spark plugs but I would sure like to see the starter and Bendix gear. :-)
I'm curious, they claim a thermal efficiency of 50%, nearly double that of an automotive diesel. How do they do it? and why can't it be done in the automotive size engine?
Karl
I make no claim to knowledge in thermodynamics - but - I think the increase in efficiency is partly due to the increase in size. Larger objects lose a lesser amount of heat (energy) than smaller ones. Common steam engines are also more efficient in the larger sizes.
More specifically, size and speed. By turning slowly, the combustion gasses have more time to expand and convert heat to mechanical force.
Do they have valves to relieve the compression to allow the thing to rotate more easily?
Best regards, Spehro Pefhany
The redline for the engine is 100 rpm. Not a lot of friction hp loss at that low rpm.
Erich
It might be due to the huge amount of metal involved, keeps the heat around so it can help in the next cycle?
ABS
On the large diesels (look like lawn mower machines next to this one) on the cruiser I was on used high pressure air to start them. This was especially nice for emergency generators since you don't have to worry about batteries...
Brad
Yes, I'm pretty sure they do. Many large Diesels release the compression by locking the exhaust valves open with a little pawl on the rocker arm, and then use a large air motor, like on air tools, to spin the crank up to a speed where compression ignition of a cold engine will suffice. (Some also use air preheating for starts at lower speeds.) The decompression pawl is often engaged before the engine stops turning, to avoid shaking the ship apart during shutdown.
Jon
The most dramatic difference compared to smaller diesels is the cross head.
Yep, a feature that is uncommon except for in double acting steam engines. Great idea to minimize wear, likely to prolong the useful life of the engine threefold.
Harold
Crossheads were very common on LARGE Diesels since the 1930's. Even some smaller ones had them. A few were also 'double acting' just like a steam engine.
Dan Mitchell ==========
Harold & Susan Vordos wrote:
Decompression valves and compressed air start would be guess......
Wow! Must admit that's a new one for me. Thanks for sharing!
Harold
The real reasons they need the crossheads is due to the huge stroke on this engine, 2.58 * the bore. Most unusual on smaller engines, as they need to fit the engine under a vehicle hood (bonnet in the UK). It requires a very long piston, with the pin very low, to do a long stroke without a crosshead. Another way to do this is to use opposed pistons, but that is a much more complicated arrangement (2 cranks, etc.)
Jon
It may have already been posted and I did not see it, but how do you start that sucker? I assume that electric motor in the forground near the large gear is for turning over the crankshaft assembly during assembly.
Hell, a 100 Taliban could hide out in that crankcase.
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The large Sulzers and MANs used compressed air to start the engine. Their was enough compressed air to get a a couple of starts, then you might have to wait to build pressure again. There was a guage on the bridge as I recall that indicated the reserve pressure. The ship used DFM (diesel fuel marine) when manuevering (starting/stopping) and heavy oil when out at sea. I don't remember the grade of bunker fuel. Some diesels can run right off crude oil.
There is no reversing gear I think it was directly coupled to the prop. To go in reverse you stop the engine and restart in the opposite direction. This means the ship had to be moving slowly in order to stop the propeller and reverse it.
I'm sure Dave Meridian is more up on the details than me.
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