Dr DTo pump up pressure on 100 train cars in order to move or to release the same air pressure - well the air would move through the long train slowly because air takes time.
This is an old wives' tale that keeps cropping up. The two compressors are to handle the larger mass of air intake that is needed to fill all the trainlines and car reservoirs; the actual difference in charge pressure from end to end is not that much of an issue when pumping up a long cut of cars. A far more important source of slow charging comes when it's cold outside and all the little seals at the gladhands, etc. are blowing by. (I remember an article in Trains, many years ago, about a dead trainload of beets...)
The added economy of cross-compound compression deserves a full discussion: how the transfer of pressure from the steam to the air is done so effectively.
STEAM ENGINE ANATOMY 101 -
There is no "mechanical blower", with a "blower fan" and "blower motor" on a railroad steam locomotive in the traditional sense!
Its just a valve and nozzle that blows some steam up the smokestack to create a draft! - called a blower because it blows air.
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The purpose of an "brake system air compressor" or better a "cross compound air compressor" is to fill the large steel air tanks with compressed air for releasing the train brakes. The compressor only runs when it is needed. Any engine designer would use as little of this steam as possible to pump air because it is a parasitic appliance and wastes steam created and used to drive the locomotive. Consequently the exhaust steam pulses out in the well known cross compound air compressor - "ka-thunk.... ka- thunk" of steam - well likely it wouldn't do more than blow the hat off your head.
Really big steam locomotives like UP 4014 and UP 844 and N&W 611 etc. had two - "cross compound air compressors" - one on each side of the locomotive - this allowed them to pump up air pressure quickly to release the train brakes. Consider on a large 100 car train doing this quickly - releasing the brakes to move the train - was important to maintain schedule.
To pump up pressure on 100 train cars in order to move or to release the same air pressure - well the air would move through the long train slowly because air takes time.
Two "cross compound" locomotive air compressors became fairly standard equipment. You can identify them because of their shape. Two pistons and cylinders pumping up and down into two parallel air cylinders - giving in effect a machine of four round chambers mounted vertically about 3 feet tall with a tiny steam engine in the middle. Check any steam locomotive photograph and look for the compressors often found under the engine forward running board ladders.
Air compressors were occasionally mounted on the side of the locomotive and early 1910 era the "single stage air compressors" were small with only one piston and cylinder. These were usually mounted on the side of the boiler above the running board. As the designs became better they eventually found their way to the front of the locomotive - usually one on each side where the "cross compound compressors" were covered with sheet metal guards to protect them from damage in the event of a collision.
Some railroads like C&O and Great Northern prefered to mount these two "cross compound air compressors" - in the "flying" position! Thats right - "flying cross compound air compressors" - even sounds racy - mounted on the front of the smokebox right ahead of the smokestack - It gave the steam locomotive a rather sporting look!
I don't think "cross compound air compressor" exhaust was ever of volume sufficient enough to bother venting up the engine stack. It was. however, one of the signiture SOUNDS or NOISES that the living and breathing operating steam locomotive made. A constant sound of "ka-thunk ka-thunk ka-thunk........ka thunk" that let you know the train brake system was being kept up to pressure to run. "ka thunk....ka thunk...ka thunk!"
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It might also be worth noting that the railroad steam locomotive was not a kitchen appliance. Considering the ban on tobacco smoking in America the breathing of coal smoke and or oil fired locomotive exhaust by the steam locomotive crew was and is a health concern. Likewise food prepared in the presence of the burning of heavy metal laden fuels was also not particularly condusive to the palate or health either.
Poison laden creasote or copper napthate preserved railroad "cross tie" campfires are also a no-no for eating and breathing.
Doc
BoydLet's say if a person theoretically emptied a 50 pound bag of popcorn into the firebox of a steamed up locomotive. I'm sure it would be a mess but would popcorn come out of the smokestack?
Boyd, you can answer this yourself. What is the temperature in a working firebox, and what is the time-of-flight of a particle (dumped in at the firedoor, in this example) through it? And thence through the flue or tube, in relatively highly turbulent flow, then a reversal through the Master Mechanic front end and contact with the 'self-cleaning' screens -- remembering what it is they do.
Now look at a piece of popped popcorn, and consider what it consists of -- its composition and its mass-to-surface-area. If you like, test a piece with a propane torch to see how long it takes to be something other than the kind of popcorn you expect to see come out of the stack. Or whether or not when it 'melts back' under the sustained heat (in the reducing conditions prevailing) it will be glowing nicely when it emerges...
That Viscose popper ... now, that's interesting. My guess is that it's acting like a giant version of a hot-air popper, with the seeds circulating in the blower draft and the popped kernels with their larger surface area being selectively ejected.
S. ConnorAn air pump would not work well as a form of draft stimulant, mostly because it does not exhaust a great enough volume of steam. You wouldn't want pulses for a draft anyways; steady and even is what you want, and the blower does just that. The blower is much easier to maintain anyways. The air-pump exhausting through the smokebox is just a point of convenience.
A Westinghouse cross-compound air compressor (which is what I presume is being meant by 'air pump' here) is intentionally designed to use the bare minimum of steam, exhausted to the lowest pressure (and hence lowest remaining heat content) to achieve the desired reservoir pressure. It does this more efficiently than most rotating pumps can. But, as noted, not only is the mass flow greatly limited even for 'banked' firing, the actual exhaust pulses are too separate and weak to provide much, if any, actual draft energy.
Note that many roads used separate external booster exhaust tracts rather than 'siamese' them into the stack for added draft, and at least some roads that started with them 'combined' subsequently separated them -- probably because the draft increased too violently with speed and started causing the usual sorts of problems with staybolts and such. There is FAR more reason to try using booster exhaust for draft than air-compressor exhaust...
The 'ideal' thing to do with compressor exhaust would probably be to condense it into feedwater, either in the tender tank or the cold-water side of a feedwater heater. That would recover the enthalpy in the exhaust steam as well as the water mass, and have the effect of reducing the effective back pressure on the LP side to marine levels. But be sure to read the various Angus Sinclair comments about 'patent' thermodynamic improvements from these types of auxiliaries...
Makes perfect sense.
An air pump would not work well as a form of draft stimulant, mostly because it does not exhaust a great enough volume of steam. You wouldn't want pulses for a draft anyways; steady and even is what you want, and the blower does just that.
The blower is much easier to maintain anyways. The air-pump exhausting through the smokebox is just a point of convenience.
Big Bill OK, probably a dumb question, but what makes the chuf-chuf on the tank engine? There's no piston movement, so it's not from the cylinders. Does the air pump exhaust through the smokebox?
OK, probably a dumb question, but what makes the chuf-chuf on the tank engine? There's no piston movement, so it's not from the cylinders. Does the air pump exhaust through the smokebox?
That would be my guess, the "chuff-chuff" seems to have the same timing that an air compressor would. Venting compressor exhaust through the smokebox would have the same effect as a blower in keeping the fire hot, at least on a small engine.
Trains, trains, wonderful trains. The more you get, the more you toot!
54light15 Down the engine room of my ship guys would heat up cans of C-rations as the food from the galley was often inedible. Put a vent hole in the top of the can and put it on a steam line and you had hot grub in a few minutes. One guy put a can of beans on and didn't put a vent in the can. BAM! It was like an episode of the Three Stooges!
Down the engine room of my ship guys would heat up cans of C-rations as the food from the galley was often inedible. Put a vent hole in the top of the can and put it on a steam line and you had hot grub in a few minutes. One guy put a can of beans on and didn't put a vent in the can. BAM! It was like an episode of the Three Stooges!
Man, that chow must have REALLY been bad if you preferred C-Rats to it!
Interesting, a friend who's retired engineer from BNSF and worked for them going back to Q days tells a story about hitting a truck filled with corn. The heat from motor popped it and their cab smelled like a movie theater for weeks.
cefinkjr Reminds me of making coffee on the exhaust manifold of an M-48 tank. (Hey, we had to let the engine run to keep the batteries charged anyway so we weren't wasting Uncle's gasoline.) SOP was to have a coffee pot on an exhust manifold if we were going to be stopped for more than 15 minutes. Irritated the heck out of nearby Infantry units.
Reminds me of making coffee on the exhaust manifold of an M-48 tank. (Hey, we had to let the engine run to keep the batteries charged anyway so we weren't wasting Uncle's gasoline.) SOP was to have a coffee pot on an exhust manifold if we were going to be stopped for more than 15 minutes. Irritated the heck out of nearby Infantry units.
Why, because they could smell the coffee and you didn't offer them any?
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
You know, I just remembered that I have a cartoon on DVD somewhere that claims popcorn was invented in a manner similar to the original question. I believe it was a stationary mill engine but the toon clearly showed popcorn coming out of the stack! And it was one of those educational cartoons too!
ChuckAllen, TX
As to burning bagasse, that was the fuel used on sugar plantations to heat the juice of the cane to condense it to the point that it would granulate. You would press the juice out of the cane, and then use the fiber that was left to heat the juice. I do not doubt that the smell of burnt sugar pervaded the operation.
Johnny
Any thread you start will be under "Your Discussions".
BoydWhy can't I subscribe to my own thread?
OK I logged in and now get replies.
Modeling the "Fargo Area Rapid Transit" in O scale 3 rail.
When I was a kid we used to pop corn in the coal furnace. We had a special covered steel pan with a very long handle that was made just to pop corn in a fire.
Saw a video of the Nevada Northern doing just that, minus the foil.
pajrrWhen I was growing up I would visit a favorite tourist railroad. The crew would be making breakfast in the firebox. Wrap bacon in foil, place on coal scoop, insert coal scoop into firebox for about 30 - 45 seconds and the result was great bacon. The crew had it down to a science.
A real crew wouldn't bother with the foil.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.
There's a scene in the Disney film "The Great Locomotive Chase" where the "Generals" engineer and fireman (engineer played by Slim Pickens) are frying bacon on the backhead!
I'm sure old-time head-end crews really did that, and I'm sure the grease was good for putting a nice polish on the iron!
Watching it made me hungry...
Well then, that's the trick! It has to be done very quickly!
When I was growing up I would visit a favorite tourist railroad. The crew would be making breakfast in the firebox. Wrap bacon in foil, place on coal scoop, insert coal scoop into firebox for about 30 - 45 seconds and the result was great bacon. The crew had it down to a science.
Sugar cane waste is officially called "Bagasse." When I started working for The Hartford Steam Boiler Inspection and Insurance Company in 1991 as an inspector, we had a form that asked what the fuel was for the boiler in question and there was oil, gas, wood, coal and bagasse. I had to ask my boss what that was. Not a lot of sugar cane waste in the Northeastern U.S. I suppose.
I was once at a beach party on Long Island with a big bonfire and someone tried to do a Jiffy-pop in it. The fire burnt it up instantly. All that was left was the wire ring and handle. Oh well. No popcorn that night!
David Wardale in "Red Devil" writes of his mentor L. D. Porta working a steam locomotive for Cuba (Porta was from Argentina, and I guess they didn't have restrictions as in the U.S. regarding commerce with Cuba, but don't everyone start getting all political on me, Porta was going to build an improved steam locomotive for Cuba).
The locomotive was supposed to burn a "biofuel" in the form of sugar cane waste, that they have a lot of in Cuba. This is not a very good locomotive fuel, and Porta needed some way to stir the charge of fuel on the firebed without requiring the fireman to constantly go at it with the fire irons. His idea was small explosive charges -- stoking the locomotive with the sugar cane waste mixed with firecrackers.
I got it, popcorn! You feed the boiler with a biofuel with popcorn kernels mixed in, and as the stoker feed contacts the firebed, you get the stirring action from popping.
Penny Trains You'd be better off doing it Jiffy-Pop style in a sealed container to prevent your corn from tasting sulfur-ish. Hey Firelock! Why are we always online at the same time?
You'd be better off doing it Jiffy-Pop style in a sealed container to prevent your corn from tasting sulfur-ish.
Hey Firelock! Why are we always online at the same time?
I dunno, spooky ain't it?
This is where I come to unwind, although sometimes I get wound up!
Anyway, Lady Firestorm's got the remote tonight and is doing some exploring. 350 channels and nuthin's on! Isn't progress wonderful?
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