Pneumatic Locomotives! Think they are safe to model?

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dorin
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Pneumatic Locomotives! Think they are safe to model?

Post by dorin »

All Things Pneumatic contains a lot of interesting topics.

Look at this website of air powered locomotives!

http://www.douglas-self.com/MUSEUM/LOCO ... irloco.htm

Just out of curiosity, any thoughts on how practical something like these would be to model?

Suppose you used a CO2 tank for pain ball...Might you have enough compressed in there to make a spin around the track?
Would it be too dangerous??

Thoughts?
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Harold_V
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Re: Pneumatic Locomotives! Think they are safe to model?

Post by Harold_V »

Judging from the comments in that link, I expect that the problems of using air for propulsion in a loco wouldn't be a great idea. It will work, of course, but I don't think you could store enough to make a trip around the track unless it was under extreme pressure, much like oxygen in a cylinder. Then you'd have the problem of refilling at high pressure. Most compressors have a ceiling pressure under 200 psi.

Like you, I'm open to comments. I do not profess to know much about pneumatics, so there may be something I'm missing.

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Glenn Lyford
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Re: Pneumatic Locomotives! Think they are safe to model?

Post by Glenn Lyford »

Well, Scuba tanks can run 3k psi or more. Not sure what that equates to in volume at atmospheric, or in total energy of the common sizes (or its equivalent in lbs. of coal or propane). Nor do I know what most dive shops charge for a refill, but I suppose Google knows all. I can see this being an option if one lives within easy driving distance of a dive shop, or are willing to invest in a scuba compressor.

Never been involved with diving/firefighting, so not sure what it would take to change a scuba regulator over to running at 100 psi typical of model engines rather than typical breathing pressures. Could be complicated, could be trivial. I suspect there's a few out on the board who may have been involved in both hobbies...?
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Re: Pneumatic Locomotives! Think they are safe to model?

Post by redneckalbertan »

You can get oxygen and other gas cylinders in a high pressure bottle, 3000ish PSI, if memory serves me. Regulators should be available to step it down to a good pressure for us. One could always make the cylinders a little larger to cope with lower pressure.

I can't remember where I heard it, but I was told some compressed air engines ran with an airline hooked up to the tank with a check valve so all the tank was used for was if the air supply quit. If that's the case one could run around with a line from a compressor hooked up... Assuming there aren't obstacles in the way.
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warmstrong1955
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Re: Pneumatic Locomotives! Think they are safe to model?

Post by warmstrong1955 »

In mines, it can be a pain, and slow, to change a flat tire in the drift somewhere by hand, so we copied the NASCAR pit guys, and got some nitrogen bottles to power the impact wrenches. Used a regular nitrogen regulator we also picked up from the welding supplier. One 280 cu/ft bottle was good for one tire change. That included jacking the thing up with a 20 ton air over hydraulic jack, and R&R-ing generally 23, depending on the machine, 3/4"NF lug nuts with a 3/4" drive impact. The regulator was set to 120-150 psi. More than that, and a full bottle might not finish the job.

I'd think a nitrogen style regulator could be adapted to a scuba tank.

Years ago, Eimco in SLC used to build some small air powered loci's for underground. (Harold??) They were mostly a tank, powered by an axial piston air motor.
I have no idea what kind of range the critters had.

I have a manual for the Eimco 401 I found on the web some years ago, but it's too large a file to download on the site. I can email it if anyone is interested.

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Rick
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Re: Pneumatic Locomotives! Think they are safe to model?

Post by Rick »

Pressurized air is not a very efficient means of doing work. Scuba tanks and most other high pressure tanks are designed and purposed just to supply gas not to have the gas do any work. Since air has to abide by the laws of nature the Ideal Gas law P=nRT/V comes into play. Assuming r(gas constant), T (temp) are n (moles/mass) are constant then the ideal gas law become Boyle's Law, P=1/V. this shows that pressure and volume of air have a linear relationship. Double the volume and pressure is halved, P=1/2V. Pressurized air carries no other energy in it other than the portion of the work (efficiency of the compressor) to create the pressure within the container (back to ideal gas law, add mass(n) to a fixed volume then pressure increases). Steam carries heat energy which changes thing drastically. You can look it up, I did, 1 gram of water turned into saturated steam will occupy about 1700 times the original volume of the water at atmospheric pressure. We use air in industry extensively because its a free, clean, convenient, easily controlled source and if you have a leak it doesn't puddle on the floor, ruin your clothes or cause some governmental agency to get excited.
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Re: Pneumatic Locomotives! Think they are safe to model?

Post by warmstrong1955 »

Here's the site with 401 info:

http://narrowgaugechaos.com/RPC/Materia ... oIndex.htm

Bill
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Harold_V
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Re: Pneumatic Locomotives! Think they are safe to model?

Post by Harold_V »

warmstrong1955 wrote:Years ago, Eimco in SLC used to build some small air powered loci's for underground. (Harold??)
I worked in the loader division, and just two weeks in the filter division before I left Eimco, so I am not familiar with the underground division that used to exist.

To my knowledge, Eimco is no more. They closed down the loader division while I was working there, which is why I ended up in the filter division.

When I started in the filter division, I requested being assigned to the smallest lathe in the facility, as I have greater talent in small work. My request was granted. I was assigned to a 17" American. I hated the job, so I quit.

Of interest to those who like railroading, the filter shop was housed in the old D&RG RR maintenance facility, the one that was once used for shopping steamers.

Harold
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warmstrong1955
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Re: Pneumatic Locomotives! Think they are safe to model?

Post by warmstrong1955 »

Harold_V wrote: To my knowledge, Eimco is no more. They closed down the loader division while I was working there, which is why I ended up in the filter division.

Harold
The underground division merged with Jarvis Clark, and became EJC. The plant in SLC was shuttered, and all manufacturing moved to Ontario.
Then....EJC was bought by Tamrock.
Then.....Tamrock was bought by Sandvik.
Talk about a soap opera.
EJC, Tamrock, and other conquests, have since been rebranded with the Sandvik label, and paint scheme.

Not sure what happened to the Eimco Process Division.....the filter guys. I worked at a mine that had a Eimco filter press, and later we added an Eimco belt press to dry stack the tailings. Don't know if they are still around under another label or what.

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Harold_V
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Re: Pneumatic Locomotives! Think they are safe to model?

Post by Harold_V »

Thanks for the report, Bill. Talk about a merry-go-round!

Damned shame the operations folded. Eimco also had a large foundry, which closed down not too long after the crawler tractor division was closed.

I've been gone from the Salt Lake City area for almost 20 years now, so I don't have a clue what might be left. Haven't been back there since the year 2000. The one thing I have learned by living in Western Washington, however, is that the availability for supplies, machine tools and materials is MUCH better in the Salt Lake area. That came as a complete surprise to me.

Harold
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Re: Pneumatic Locomotives! Think they are safe to model?

Post by steamin10 »

scuba tanks of steel and aluminum run the gammut of 50 to 120 cf and pressure t 3500lb. I have used them for tire filling and air chisel work in remote spots. One of the gas laws explain that the most volume of a gas is stored at the lowest pressure. so as pressure drops fast on the high end, it slows and give up the same volume for lower pressure loss. in general, it is not efficient for locomotion, unless any fire or fume is important, such as chemical plants, munitions, and mines, and where air quality is paramount. I should be noted that early torpedoes were air motor powered, and then battery, and then alcohol engine supplied with oxygen from a flask. (bottle).

In mines, there were air lines everywhere for the drills, so topping up a tank was simple at 200 psi or so. Othewise an energy wasting booster of unequal piston size would pump high pressure air from a low pressure line. This was an early answer for compressed scuba air in the 70's, when the first 3000 lb scuba bottles appeared. Smaller units were home available to run from a shop compressor. The idea never took off well. I used to go to the local fire department on a weekend and fill my tanks on their fire supply, and BS with the guys. I finally got a 3 bottle bank of oxy bottles and made a cascade to fill at home from my booster. Never got a high pressure scuba pump.

IMHO and air engine is neat, but fiddly for a run on tracks, many limits must be observed. I read somewhere out East a gentleman ran an air engine on his rails, with the engine and 1 tank car making the entire round and being recharged for another go.
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Re: Pneumatic Locomotives! Think they are safe to model?

Post by warmstrong1955 »

steamin10 wrote: In mines, there were air lines everywhere for the drills, so topping up a tank was simple at 200 psi or so.
True on the piping. Used to be that most everything in an underground mine was pneumatic.

System pressure though, is and has been a nominal 100 psi, not 200.
Most modern DTH (Down The Hole) drills use 'high pressure' air, 250-350 psi, but they have their own electric powered booster compressors that feed off the existing mine air.

Not sure how often those old air loci's needed to be filled, but yes, it would be easy to slap a hose on it when you were unloading cars at the pocket or on the dump every trip. No experience with those critters....they were used before my time. Air muckers like the 12B, and jackleg or jumbo drills were all designed to run off the 100 psi system pressure, as most all UG equipment.

Trivia....

:)
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