I’m not much of a steam fan (born too late…). However, my wife and kids got me a group of steam DVD’s for Father’s day,[:D] with lots of old railroad footage.
Some steam questions:
What is the steam coming out of a stovepipe(or sometimes 2), right above the front of the cab.
What is the big burst of steam, coming straight out from the cylender.
What is the deal with the smoke from the stack? Sometimes black as coal, sometimes pure white, many times a shade of gray, and sometimes nearly invisible?
the thin whisp of steam could be from a turbo generator for electricity…a large gushing plume of steam from the same area would be the safety valve
the big burst from the cylinders would be the cylinder cocks…steam condenses to water in the cylinder in a standing loco…water doesnt compress so it must be removed or it will cause damage
the color of the exhaust depends on many things…how hard the enigine is working…if the fireman is “pouring on the coal” …even the type of coal thats being used… thottle postion…cut-off postion
correct…when a steam locomotive sits…as in a station…the hot cyinders cool and the steam left over condenses to water…if that water in the cylinder isnt removed when the throttle is opened the piston trys to compress the water which doesnt compress…the hydraulic pressures causes serious damage…bent drive rods…bent piston rods…or even blowing the cylinder covers off…so the engineer will open the cocks usually just before opening the throttle and allow steam pressure to blow the standing water out of the cylinders…most times the cocks will be open for just a short time…maybe 3 or 4 revolutions …it makes a pretty picture but it isnt very effiecent…when a steam loco starts off the reverser or “cut-off” will be full forward allowing full boiler pressure in for almost the full piston stroke and all that steam escaping out the cocks isnt helping to move the train
When hand firing a lightly loaded steam engine, the coal burns in several stages - each with a different smoke color. A couple of shovels full of new coal (green fuel in fireman terms) cool the fire a bit so that combustion is not as efficient - contributing to black smoke. As the surface coal dust burns off, the coal heats up and releases any water and volatile gases. These contribute to white smoke. (Note - white smoke in an oil burner may mean your flame has gone out. Oops.) Finally the hot coal starts burning white hot like coke - this gives the hottest flame and a light gray smoke. This is ideal.
A good fireman is contantly adjusting the drafts and loading green fuel to keep most of the firebox burning at the light gray smoke level. Any holes in the fire will cool the flame and lower steam production. Any piles or humps in the fire will smother the coal and can cause clinkers to form. Clinkers in turn prevent good combusion so you want to break up the clinker as soon as you detect it.
I understand the practice and reasoning behind cylinder cocks and the practice of opening them as an engine is started. Are there any circumstances where cylinder cocks are opened while a train is under way, such as when drifting? I have seen photos showinging a lot of steam emanating from around the cylinders on engines that are likely to be under way, rather than just starting. Would it be common for there to be considerable leakage around the cylinder or valve rods?
The cylinder cocks are almost always opened when drifting with a closed throttle to prevent the vacuum in the cylinder from pulling smoke and cinders from the smoke box into the cylinder. I don’t know how common rod leakage was in practice. It is a sign of wear.
Thanks for that information. So, when drifting with the cylinder cocks open, would there be cases where the throttle might be opened slighly to work a little steam?
Or, might an engineer drifting with the cylinder cocks open, end drifting and begine pulling by begining to open the throttle a few seconds before closing the cylinder cocks?
You’ve gotten several good responses. Just to add a little:
The cylinder cocks might be opened with the locomotive is moving for a couple of other reasons. First, having them open allows more a open throttle and/or cut-off for a given amount of speed/pulling (load). This can be beneficial under some circumstances. One engineer I know does this when running through a tight curve at low speed. (Having your cut-off as near 100% as possible can smooth out the piston stroke; otherwise when the steam stops entering and the adiabatic expansion starts, the stoke changes).
Also, of course, often the cylinder cocks are opened to generate more visual excitement for a bystander, photographer, or videographer!
As to the color of what comes out the stack, it is affected by the mix of steam and firebox exhaust gasses. On cold days the steam condenses into billowing white clouds. The exhaust gasses change color depending on variable of combustion. Generally, black smoke means incomplete combustion, i.e., a waste of fuel. The fuel-air mixture and, in a coal burner, coal related variable affect this. But even a good fireman might generate black smoke when the locomotive is working hard, especially with rapidly increasing load.
Again, though, some firemen generate black smoke on purpose at times to appeal to the masses.
Every time the throttle is opened from closed postion - you want to have the cylinder cocks open for at least a couple of minutes to drain any condensation in the lines that occured while the throttle is closed.
The same is also true of steam powered appliances such as the air pump - open the air pump valve - wait a few minutes - close the air pump drain cocks.
The flues get coated with soot and can actually clog up completely. Periodically, the fireman would pour sand into a little hole in the firedoor and the draft over the fire would blow it into the flues and “scour” the soot out. Well, actually, “pour” is not quite it… the draft would suck it right off the scoop when the little door over the hole was moved out of the way. I don’t think this was ever done in a coal fired loco… the coal dust does the job. Oil burners needed it often. Just don’t do it at the station! Greasy sand all over the place! And don’t do it too often, just want to remove the soot, not grind metal off the flues and superheater tubes!
I’m startin to understand why engineers were usually asigned to their own locomotive. It sounds as if each locomotive would act a little differently under differing operating conditions. Perhaps it was best to have an engineer who could feel how his locomotive was operating.
If I recall correctly, “Drifting Throttle” was just a setting on the throttle that allowed just enough steam to flow to carry lubrication to the cylinders while the engine is “coasting”. Not enough steam to cause acceleration, just enough to lubricate things. The Reverser Lever was put in the “Company Notch”, the point closest to neutral yet still set to the direction the engine was moving. This also limited the amount of steam pressure available in the cylinder so as to cause no additional acceleration.
That about sums it up. Here is a video from the Kettle Valley Steam Railway. In the first minute or so, you’ll see a two-truck shay sand out the flues. http://www.youtube.com/watch?v=WqE5Ew-xIKo
Your comment above caused me to think back some 55 years ago to the time when I was a fireman on the ICRR and runs contrary to what I recall. I don’t believe that the cylinder cocks were normally opened when drifting. It seems to me that this was unnecessary because there was a bypass valve which prevented a vacuum in the cylinders. When the throttle was completely closed, as it would be when drifting, this valve would open to provide a direct connection between both sides of the piston thus equalizing the pressure on both sides and prevent the creation of a vacuum. The bypass valve was actuated by either a mechanical linkage with the throttle mechanism or possibly a small air or even steam piston controlled by the throttle position. I’ll hasten to add that I stand open to correction - I’m going from observing and talking to the hoggers I worked with and my recollection of any details has been dimmed by the passage of so many years since that time.
I worked on the Illinois Division of the IC which was had few grades of any length. I can visualize that on a long mountain do