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Compressed air/Steam locomotive

8K views 37 replies 18 participants last post by  East Broad Top 
#1 ·
Here is the thread clip from where it all started.

Jason - How about one of those old compressed air locos. Always thought that would be interesting to make one and have a air tank on it. Need to fill up at least 120psi do decent run time if a few mins id guess depending on the cylinders.

Henner - Jason,
we have thought about building such a compressed air loco. Unfortunately it seems almost impossible. 120PSi would give you probably just a couple of seconds of run time (120PSi expanded to say 12PSi = 10 times the volume of the boiler). Even 1200PSi would not cut it.
We also thought about dry ice (CO2), but here you run into two problems: Either the sublimation rate is too low or if the loco sits for a while, it creates dangerously high pressures. There have been attempts to sell dry ice powered locos, but they disappeared rapidly from the market...
Regards

Jason - Henner what about using the cans from a paintball gun? Of course refilling is the issue then.

Dan -
Real fireless engines were charged with steam. Unlike compressed air, as it was used it would still expand. The exhaust was reused, I don't know how. Most of them were small 0-4-0's and would run a full 8 hour shift and have enough pressure to make it back to their "charging" station. Many years ago there was one in Ft. Steel, BC that still ran, it's doesn't now.

Henner - We should not hijack Bill's thread. We could open a new one.
A fireless loco charged with steam would not work due to the rapid heat loss in a model. A paint ball tank might work. I just made a quick calculation and the range would be close to a mile (67cubic inches at about 3000PSi -> 6700 cubic inches at 30PSi). But you need to integrate the tank into a loco and also find space for the pressure regulators (probably two step). And then of course refilling the tanks.
Regards
 
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#33 ·
Interesting, I wouldn't have thought compounding would work on a compressed air locomotive because you don't get the same expansive properties on air that you do with steam, so at first I thought maybe they used four cylinders of equal size to get more piston area in a limited loading gauge. On closer inspection though, that does indeed look like a Vauclain Compound, with the smaller high-pressure cylinder on the bottom and the larger low-pressure cylinder on top. Definitely an air lokie too, with the uninsulated tank and radiator fins on the cylinders.

The one in the third photo is interesting too. It was a fireless steam locomotive built by Baldwin for the Minneapolis Lyndale & Minnetonka Railway, which used a chemical reaction of caustic soda and water to generate the heat to boil water into steam (rather than simply use the gas from the soda reaction). The unit in this photo would have been enclosed in a wooden streetcar-style "steam dummy" carbody in service. More info on the "soda motors" here: http://streets.mn/2012/05/18/the-motor-line-and-its-fireless-soda-locomotives/
 
#35 ·
In testing my compound Heisler, I found that it ran just fine on air, probably better than on steam as you don't have the condensation problem you do with steam.
On the expansion of steam, It expands because it is under pressure. Compressed air )or any gas) will do the same thing.
The power for the low pressure cylinder comes from two things:
the remaining pressure in the high pressure cylinder when the exhaust port opens and
the air compressor action of the high pressure cylinder as it is exhausting.
 
#38 ·
If you're ever in Cripple Creek, CO, take the Molly Kathleen mine tour. Besides being a really cool tour in its own right, it includes a ride behind an air-powered mine loco.It looks similar to the one shown above, but if memory serves, the ones used in this mine were home-built.

Definitely an interesting idea using paint-ball canisters.

Later,

K
 
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