In the pre-electric days, how did they operate the huge fans at the top of the vertical shafts that exhausted smoke and gasses from long tunnels? I’d assume steam power for lack of anything else, yes?
So then did they have 24-hour, 7-day crews up there on duty? How did they move fuel and water up the mountain to operate the steam engines? Or did they use a system of belts and pulleys from steam engines at track level? Did the fans operate only when a train came through?
The shafts on the tunnels at Gallitzin, Pa., and Gray Summit, Mo, have been sealed since the steam era. Do any old vent shafts still exist, in operation?
I could be wrong, but I don’t remember reading about any “tunnel tender” jobs on the railroads. I thought most tunnels of that era used Mother Nature to clear the air. That’s why crews hated them on busy lines (more than 4 trains a day). I believe mechanical ventilation of RR tunnels didn’t become popular/desirable until after the means to acheive it cheaply were available.
A video I have about the Norfolk Southern says the tunnel ventilator fans were controlled by the dispatchers. Some tunnels had doors at each end that could also be remotely opened and closed by a dispatch center.
This assumption from a man who keeps learning how little he knows, but I would have thought the very trains, themselves, would do a passable job of running cleansing air through the tunnels when the locomotive had passed in the lead. Each car front acts like a mini-impeller blade as it enters the lead portal and encourages a bowshock of air to move ahead of it as it makes its passage along the tube. Or, so it would seem natural to hope. So, why doesn’t it?
I can see that a hard-pulling Class Y, or two of them, struggling to yank 8000 tons at just over 10 mph might not get that result as the cars aren’t generating much of a front, but after 30 mph they ought to do much better…or…what?
I vaguely remember a story of a tunnel in Switzerland where some number of passengers died due to smoke left by the previous train. I don’t remember the details, except that a law was passed that required a person to be stationed at each end of the tunnel and no train would be allowed to enter until they could look through the tunnel and see each other.
Have you ever seen the photo of the SP’s “breather apparatus” for engine crews… right out of a 1930’s “space” movie.
…But aren’t those entrance “doors” on some tunnels there to keep the air from moving as a train makes it’s way thru the tunnel…so the engine has “new” air to cool the coolant in the engine cooling system.
In other words if the train was “pushing” the tunnel air ahead of it all the way thru…the radiator would be trying to remove heat from the cooling system with already warmed air since it is stagnant, and riding along with the train…
The NP tunnel at Mullan Pass had a siding for coal cars which dumped their loads to feed a steam plant at the east side of the tunnel. There were two fans which may have been belt powered at first but were eventually electified. I do not know if the steam plant generated electricity for that or not.
No way.The idea forthe vertical ventilation was to keep train crews and passengers from being asphyxiated while the train was in the tunnel, not to clear the tunnel behibnd the train, which is what your piston effect would do in a very short tunnel not in one over an eighth mile long. In long tunnels it would cause a mild compression at the locomotive and a mild lowpressure turbulence just behind it that wouldactually drive the smoke and gasses into the cars. Chimneys breathe because the air moving horizontally across the stack creates negative (low) pressure which pulls air up the flue. Same principle of lift on an airplane wing.So your one portal higher than the other idea would not work – can you find examples?; I doubt it.And don’t try to say the tunnel was built on a grade to get one portal higher than the other, the last thing they needed was to work a steam engine harder in an enclosed space.
#1 DO a google for “piston effect tunnel ventilation” and you’ll see for yourself
#2 Really? so then if there is no outside wind, one better not light a fire in the fireplace? The effect you cite may apply to moving smokestacks, but when contemplating CHIMNEYS (which is what I said, not “smokestack”) heat naturally rises, forming a draft as warmer air passes
#1 DO a google for “piston effect tunnel ventilation” and you’ll see for yourself
No need. First, the pitson effect works in short tunnels of singletrack with tight tolerances betwen tunnel walls and train cars on high speed trains.But theoriginal question was about pre-electric days when the steam trains moved at slower speeds through long tunnels which didn’t move as much air.There was no piston effect if the train had to make an emergency stop in a tunnel.And if the tunnel was double track like at Altoona there was no pitson effect at all. You should read the finest book of the era Practical Railroad Engineering by Clifford F. Bonnet (start on page 173).
#2 Really? so then if there is no outside wind, one better not light a fire in the fireplace?
If this is the extent of your knowledge you better stay away from matches.[(-D]
The effect you cite may apply to moving smokestacks, but when contemplating CHIMNEYS (which is what I said, not “smokestack”) heat naturally rises, forming a draft as warmer air passes
A proper vertical chimney without a fire will pull a slight draft (lookup ambient chimney draft), and moreso if there is a wind blowing across its top. You answer your own question - a chimneuy with wind moving air across the top is no different than a smokestack on a moving traion pulling some degree of draft. Same as putting a lighted cigarette into a bottle and blowing across the opening will create the same type of lift present in proper aiprplane wing designs. Wind moving at speed hotizontally across the top of a wing or across the opening of a chimney will cause a low pressure condition which results in lift. While heat from a fire will also mov
I’ve run them, and theres not much draft pulled on moving smokestacks on steam locomotives, not at all. The pressure on a steamer smokestack is from the inside of the smokebox out - the exhausted low-pressure steam is directed forcefully upwards through the smokebox and out the stack which really causes a suction causing a negative pull back in the firebox. It sucks in more air through the flue pipes from the firebox pulling air into the firebox and making the fire hotter and the fireman shovel harder. The faster the loco goes the more exhausted steam and the stronger the draft and the better the fire burns.Locos stored outdoors woth banked fires overnight on very windy nights often had the hostkler put a stack cover on so the coals would slowly smoulder all night instead of burning away.
The reason that all long tunnels are sloped is for drainage, not air movement. Sand Patch Tunnel on CSX has a ventilating shaft in the middle, in steam days there was a chimney on top to enhance the movement of air up and out of the tunnel. Piston effect works well for faster moving passenger trains, but poorly for slow moving freights. I have ridden the Empire Builder through both Flathead and Cascade Tunnels, the air quality is much better in Flathead than in Cascade, although train speed is higher in Flathead Tunnel. A picture of a westbound freight coming out of Mullen Tunnel on the MRL is something to behold, the tunnel doesn’t have mechanical ventilation and train speeds are low with 4 or 5 locomotives on the head end, the smoke boiling out of the tunnel just ahead of the train and then swirling around the locomotives and cars. Respirators are required to be on board, in case the train stalled or had to stop, strong winds out of the west also cause extra problems. On tunnels with doors, the door is always located on the uphill end, and air is forced in from the end with the door. Mt. MacDonald Tunnel, on the CP, has two doors and two sets of fans.
I have a history book on Swiss railways and there is no mention of a diaster of a passenger train in a tunnel. The book is published by the SBB Historical Foundation.
Beaulieu is right. The accident in the Rickentunnel on the Bodensee-Toggenburg-Railway did not concern a passenger-train. I found the following text in wikipedia. It was a freight train, hauled by a Swiss-Federal-Railways mogul. The accident happend on 4-10-1926. The tunnel (5+ miles) lacked ventilation and had a bad reputation among crews. It was in a 1,5 % grade. The engine was fired with a kind of coal that generated high quantities of CO and less steam than the coal previously used. The train stalled in the tunnel, and the crew died, while trying to start the train. A first rescue-attempt ended dramatically with three rescuers dying, too. Only a second rescue-attempt was successful. In 1927, Swiss Federal Railways electrified the tunnel and banned steam-engines from it.
By the way, the Arlberg-tunnel on the namesake mountain-railroad in Austria was known for the center-section being often very sticky. It was one of the first mainline-electrifications in Austria.
Here is a little pistion effect being demonstrated by a coal train coming out of Mullan Tunnel as beaulieu mentioned. I posted this once before in another thread on smoke, but it fits here and is fun to watch (unless you are Al Gore).
…Interesting video…Alarming, if there would be crew in the following engines…{I’m assuming there was not}.
Under this specific situation, I’m even wondering how the following engines have enough oxygen to continue to run…?? And these weren’t even steam engines…! {Smoke…}. One would think smoke would be minimal. But realizing if it is upgrade, they probably are in notch 8 and by the appearance, some seem to be “over rich in fuel”, or whatever causes all that black smoke.
It is a lack of oxygen in the tunnel that causes the smoke. The oxygen is reduced while the fuel delivery remains the same, so the condtion is “over rich in fuel” as you say. The last engine seems to be smoking more than the others, but I think they are all clearing up as they get further away from the tunnel.
Is this a more or less routine occurrance with such trains coming through this tunnel? If it is, it sure would seem to be an attractive photo shoot location, and I would expect to see more videos of the performance.