This is by far the weirdest preserved steam locomotive I have ever seen. I am honestly surprised that it even made it into preservation. Does anyone have an idea of what its purpose was? I imagine the re arranged exhaust was to help in long tunnels?

https://www.youtube.com/watch?v=PghVeJw4xHw

I'm kind of at a loss to comment on this. Oddball is a good name for it. Sounds like a steam engine anyway.
Where is it? France? Italy?

My guess was Italian, but it is possible that it is either French or Swiss?

Italian! And if you look close in the old Frank Sinatra movie "Von Ryan's Express", you can see one of these engines involved in the chase.

Les

This is what is known as a Franco-Crosti boiler. There's a nice article on Wikipedia about it, including photos of the 741.120. Link is here: http://en.wikipedia.org/wiki/Franco-Crosti_boiler

I wonder how many other Locomotives of this boiler design made it into preservation? And I also wonder about the engine used in Von Ryan's Express; is it safely preserved somewhere?

More then one. This one is at the railway museum in Pietrarsa, just south of Naples.

Definitely an interesting design for sure! I am guessing that it has problems ejecting the ash from the boiler, hence the new location of the stack and the longer path it has to travel. Would this make the second door beneath the smoke box door specifically for removing the ash that collects in some special ash hopper?

Just as an aside, I have NEVER seen so many people step on the rail head in such a short period of time... I counted ten, but a couple in the turntable scene might get a pass because it appears the track may have been filled with ballast to railhead height, it was hard to tell. The crew seemed to be the worst offenders... maybe they wear magnetic boots in Italy?

The UK tried the Crosti boiler on a standard class 9F too...

http://en.wikipedia.org/wiki/Franco-Crosti_boiler

Mike Pannell

This video warrants 5 comments (some to the folks who shot this):

1. The Crosti looks odd, but sounds awesome.
2. Is there a chiropractor on board for the peeps in those two axle bus bodies?
3. Thank you for using a tripod
4. Thank you for not molesting the zoom button
5. Thank you for not panning like a madman.

Nice work

Rob

This reinforces the saying among modelers (of which I'm not one): "Whatever you want to do, there is probably a prototype for it somewhere".

A friend offered a better explanation of these engines and asked me to post it here. This is a summary of our conversation:

The large chamber under the boiler is a big feedwater heater. The exhaust boiler gases passed through 2 sets of tube before being ejected out the side mounted stack. The exhaust comes out of the front tube sheet (of the boiler proper), then gets sucked down the smokebox, into the heater below the boiler. The back of the heater contained another open space, similar to the smokebox, that was connected to the stack on the side.

The Crosti Boiler was also applied to locomotives used in France as well as the UK, where this system was applied to a few British 9F 2-10-0's but was quickly removed because they proved too high maintenance.

The last stage set of tubes corroded very quickly depending on the coal. Coal with a high sulphur content was murder on the last pass of tubes.

The problem is that with the extra heat exchanger, enough heat is extracted from the exhaust gases to cool them to the point that the moisture in them begins to condense. This condensing moisture transfers additional heat to the incoming water, but it also combines with the sulfur in the gases to form sulfuric acid. I recall reading that some of the engines with Franco-Crosti boilers used enameled tubes in the heat exchanger to try to combat this.

Modern "condensing" boilers gain efficiency in the same way. They deliberately cool the exhaust gases enough to cause condensation, allowing additional heat to be extracted and allowing 90%+ thermal efficiencies to be obtained. Of course, most of these boilers burn natural gas which is a relatively clean fuel, so only a little sulfuric acid is formed. Even so, these boilers are at least partially equipped with stainless steel tubes to prevent corrosion and have devices to neutralize the acid before the condensed water is discharged to the building's sanitary sewer system.