Hello again!
In this next part of the quiz, we move up from the running gear and into the heart of the locomotive: the firebox and boiler.
We all know that the firebox is the core of any steam engine, but do you know all the various parts that make up a firebox? They are a bit more complicated than they appear!
1.: What are the "Backhead", "Mudring", "Crownsheet" and "Neck", and where are they located in the firebox?
2.: What is a "Syphon" and a "Circulator"? How do they work, and how do they differ?
3.: What exactly are grates? What do they look like and how do they work?
4.: What 3 functions does the "Brick Arch" in a firebox perform?
5.: How are oil burning fireboxes different from coal burning fireboxes?
6.: What are "Watertube Boilers"?
Bonus: We tend to think that the various auxiliary parts of a locomotive were all made by the main builder of the engine (BLW, ALCO, Lima), but this isn't actually the case. Scores of small specialized companies developed and manufactured many of the smaller components of a locomotive (actually not just the small parts, but almost everything except for the cab and boiler shell!). One good example is the automatic coal stokers. There were a couple of competeing manufactures who built and sold their own brand of stoker. Can you name them?
That's it for this part of the quiz right now. I got a lot mre to add to it though, and I'll add more questions as these get answered. (I told you the firebox was a lot more complicated than it appears to be! Just wait until I get to boilers and front end arrangements!!!)
Good Luck!
Matthew Imbrogno-Mechanical Vollenteer, Arizona Railway Museumwww.azrymuseum.org
I almost forgot to toss my ante into the fire! It aint fair if I make you answer all these questions if I don't give one myself! I won't answer one of your's though, I don't want to take your fun away!
The subject is Staybolts: Staybolts are the houndreds of bolts that hold the inner firebox and the boiler shell together. Because a waterspace has to exist around the firebox, between it and the outer boiler shell, some sort of spacer is needed to keep everything together in proper alignment. Also, because of the pressure in a boiler, and because the firebox plate needs to be as thin as possible to conduct heat to the water efficently, the firebox needs to be supported and held against the pressure to keep from buckling inward. Staybolts act like a suspension system, litereally 'hanging' the firebox from the boiler shell. When you view the outside of a firebox, and see all those bolts and nuts on the side, those are the crownbolts. They pass through holes drilled through the boiler shell and firebox.
Staybolts have two or three parts: a seat in the boilershell which is custom fitted to the contour of the plate, a threaded rod or "bolt", and another seat on the inside of the firebox. The seats are specially drilled and tapped into the plates to ensure a pressure-tight seal. Many of the later staybolts have sealed caps with bolt ends fully contained inside them, so that there is no gap or crack to let steam escape. Some staybolts have only one cap or seat, with the other end of the bolt being riveted straight to the boiler plate. These are prone to leakage however, and fell out of favor in the thirtys.
There are two types of staybolts: Static and flexible or Radial-Stayed bolts. Static bolts are generally used on the lower part of the firebox, where the firebox and boiler shell plates are perfectly parallel and not subject to much flexing or sheer. Flexible staybolts are used on the upper, curved sections of the firebox, where changes in pressure will cause the sheets to expand or contract, distending them out of their usual alignment. This puts such stresses on the bolt that if it were of the standard "fixed" variety, it would pry the seats loose with the sideways forces. The Radial staybolt has a ball joint in the seats, much like the joint of your shoulder, so that the bolt can pivot and sway with the plates without being sheered out of it's seats.
Staybolts are the most crucial part of a firebox. The hold the firebox and keep it from imploding under the pressure. The firebox is the waekest part of a boiler, as it is subject to the most heat, and it isn't the strong round shape of the boiler tube. It is further weakend by the houndreds of holes drilled into it for the staybolts. Added to this is the way of how when steam boils, it creates a swirling rolling force of water that pushes against the plates. When you take all that into account, you begin to see just how strong the boiler needs to be!
When a staybolt is weakened and breaks, it can cause a shockwave that puts extra strain on the surrounding bolts, snapping them also. This sets of a chain reaction, and all the staybolts of a boiler can blow in a fraction of a second. Without any support, the thin firebox sheet is blown through by the tremendous steam pressure, causing a boiler explosion. It is in this type of explosion that the boiler gets ripped off of the locomotive frame, and driven like a rocket by the hole in the end of it, it can land up to a mile away.
I have a postcard of a boiler that had landed in the lawn of a small house. The boiler tube was intact, but the firebox was blown apart. It was a smaller engine, probably of 150-200psi, and it landed a full 1/4 mile away from the nearest railroad track.
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Ok now! SDR_North knows a lot about fireboxes! There are still a few openings for the rest of you though!
SDR_North got #1 absolutly right, and #2 half right; we're still looking for the definition of a "Circulator". Thank's also for your very thorough description of Grates, although I'd like to add a little to that.Grates are not only triangular, but they can also be eliptical or flat rectangular. Grates are hollow on the inside, and have slits in the top to let air through. They were more like a grid mesh, literally a "grate" or "grating".
For #4, Deflecting heat is only one job that the brick arch does. What are the other two?
Number 5 and 6 are both good answers, but a little elaboration on the arrangment of a watertube boiler could be usefull.
Now for some additional questions:
#7: what are "Drop Plugs", How do they work?
#8: The accumulation of soot and ash is not a critical problem, but it plagues engines by blocking the transfer of heat from the fire to the water. How do crews clean the soot off of a boiler while on the road? While in the shop?
#9 What are you doing if you are "Wabashing" an engine?
And another bonus: For those of you who have read "Rio Grande Glory Days", what happons if you try to burn Gilsonite in a locomotive? I've also read about burning tires and other non-standard fuels in an engine during an emergancy. Have you heard of any similar experiances?
Feel free to add any questions you'd like to if you have any! I've been looking for a real stumper!Matthew Imbrogno-Mechanical Vollenteer, Arizona Railway Museumwww.azrymuseum.org
Mimbrogno wrote: Ok now! SDR_North knows a lot about fireboxes! There are still a few openings for the rest of you though! SDR_North got #1 absolutly right, and #2 half right; we're still looking for the definition of a "Circulator". Thank's also for your very thorough description of Grates, although I'd like to add a little to that.Grates are not only triangular, but they can also be eliptical or flat rectangular. Grates are hollow on the inside, and have slits in the top to let air through. They were more like a grid mesh, literally a "grate" or "grating".For #4, Deflecting heat is only one job that the brick arch does. What are the other two?Number 5 and 6 are both good answers, but a little elaboration on the arrangment of a watertube boiler could be usefull. Now for some additional questions:#7: what are "Drop Plugs", How do they work?#8: The accumulation of soot and ash is not a critical problem, but it plagues engines by blocking the transfer of heat from the fire to the water. How do crews clean the soot off of a boiler while on the road? While in the shop? #9 What are you doing if you are "Wabashing" an engine?And another bonus: For those of you who have read "Rio Grande Glory Days", what happons if you try to burn Gilsonite in a locomotive? I've also read about burning tires and other non-standard fuels in an engine during an emergancy. Have you heard of any similar experiances?Feel free to add any questions you'd like to if you have any! I've been looking for a real stumper!Matthew Imbrogno-Mechanical Vollenteer, Arizona Railway Museumwww.azrymuseum.org
4. The brick arch also increases the length of the combustion chamber, allowing more complete combustion of the gasses released from the coal.
5 & 6. Water tube boilers are constructed essentially backwards from a fire tube boiler, which was the most common on a steam locomotive. Because of their construction (and methods available at the time) they weren't as rugged as the fire tube type. Not sure what other elaboration you're looking for.
7. Drop plugs (AKA fusible plugs) are mounted in the crown sheet and made of a metal that will melt before the steel of the crown sheet. In the event the the crown sheet does run dry, these will melt out and blow the steam into the firebox which will blow out the fire, and hopefully this will all happen before the boiler explodes. Also, you hope the firebox door isn't open and noone is standing in line with it when this happens.
8. Soot on the boiler isn't a problem, it just makes the locomotive look dirty, but it is when it is inside the boiler tubes (flues) and starts to reduce the size of the opening. It not only insulates the tube, restricting heat transfer, it also inhibits air flow through the tubes, cutting back on the draft for the fire.
Instead of a stumper, how about an easy one: Where would you find a petticoat pipe?
Mike WSOR engineer | HO scale since 1988 | Visit our club www.WCGandyDancers.com
We got some more good answers!
We had several good swings at #4, and we got some of it, but let me fill in what else I was looking for. In addition to difflecting the heat and spreading it more evenly around the firebox, the brick arch acts as a bottleneck, forcing the draft into a smaller opening, and accelorating the smoke and used air off of the fire. That helps boost the draft volume and hence the fire temperature. Another, more subtle thing that the brick arch does is it helps control cinders and ash. After the air passes through the narrow opening at the rear of the firebox, it enters the larger space in the upper forward part as it passes through the neck and enters the tubes. Because the arch is built on a downward sloping angle, the heavier cinders and ash fall into the bottom front corner of the firebox, where it is collected and removed. That helps to reduce the amount of wear on the tubes and flues.
You guys got #7 dead on. Locomotives usually have 3 to 7 fusable drop plugs running down the middle of the crownsheet. Each successive plug melts at a slightly higher temperature, so that if one plug doesn't reduce the heat enough, additional plugs will fall out to ensure the boiler won't fail (hopefully).
On number 8 I'm glad you guys mentioned the locomotive's soot blower. I don't know how well known it is, but in the 30's an automatic soot blower was developed that cleaned the firebox while the engine was on the road. It took the form of an articulated arm with a steam nozzle on the inside of the firebox. It would run back and forth along the sheets, knocking of the soot to keep the boiler in top form.
Wabashing may be a local term, the reference I heard it for was on the Rio Grand Southern.
Now then, I'm glad to get some questions on my side of the fence! The answer for what a pettycoat pipe is the inside part of the smoke stack, which extends down around the exhaust nozzle of the cylinders. It is an induction hood that is responsible for creating the draft for the fire.
HydroKineter; boy that's a term I don't hear very often! That's a circulating pump in the boiler that stirs the water up when the boiler is 'idling'. It keeps the water moving so the water at the bottom of the front of the boiler doesn't cool off.
Now then, I got a really tough one for you guys here, so lets see what you're really made of!In the late 1800's many builders, especially Baldwin, began experimenting with Soda powered locomotives. Just how in the heck does a soda powered locomotive work? Why was there so much interest in them during that time? Why was the technology abandoned?
Got any other tricky questions?Matthew Imbrogno-Mechanical Vollenteer, Arizona Railway Museumwww.azrymuseum.orgBelieve it or not, I've never worked on steam engines, I've really only worked on diesel engines!
Mimbrogno wrote: Now then, I got a really tough one for you guys here, so lets see what you're really made of!In the late 1800's many builders, especially Baldwin, began experimenting with Soda powered locomotives. Just how in the heck does a soda powered locomotive work? Why was there so much interest in them during that time? Why was the technology abandoned?
Middleton's "The Time of the Trolley" mentions work on the soda motors. These relied on the exothermic reaction of adding water to a concentrated sodium hydroxide solution to create heat for the boiler. The intent was to have a fireless steam locomotive to replace horse power for street railway operations. These were being developed about the same time that Sprague was perfecting his system of electric traction and electric operation turned out to be the better ay to go.
As for water tube boilers, the D&H experimentals had a pair of drums on each side of the boiler, the upper one was for collecting steam and the lower was a reservoir for the water tubes. There were two rows of tubes on each side of the firebox, the inside one received most of the radiant heat and thus geneated the steam, the outer ones served as downcomers.
We have an excellent response from Erikem on both Soda motors and D&H's watertube boilers.
Soda motors were indeed intended for street railway service because they had one very significant feature, they had no exhaust of any kind. As far as operating a Soda motor is concerned, it is just like a fireless steam engine but with a much longer endurance. The "boiler" is really two pressure vessels, one inside the other. The inner tank held pure Sodium Hydroxide, while the outer 'main' tank held water and steam. To begin operation, the main tank was charged with superheated water and steam from a stationary boiler. The inner tank was partially filled with 'dry' Sodium Hydroxide, also known as "Caustic Soda; hence the name of the engine. As the engine ran and used up the stored steam, the used steam was discharged into the inner vessel filled with the caustic soda. Conventional fireless steam engines on the other hand, simply discharge the used steam into the atmosphere. When the used steam, which by now has cooled to the point where it is only water vapor, meets the soda it causes a chemical reaction in which the soda combines with the water, generating heat. Enough heat is made in the innor tank that it continues to boil the water in the main tank, producing more steam to power the engine. The sodium hydroxide solution also boils at a lower temperature than water, which means that the heat of the reaction won't generate pressure in the inner tank to counteract the pressure of the main tank at the pistons. The end result is that the engine will keep running as long as there is enough sodium hydroxid left to absorb the water from the exhaust, and it is not solely reliant on the pressure of the initial charge.
More information about Soda Motors can be found on this very informative and fascinating webpage:
http://www.dself.dsl.pipex.com/MUSEUM/LOCOLOCO/soda/soda.htm
It is interesting to note that while Soda motors had been all but abandoned by 1900, the technology would still intrigue inventors for decades. As late as 1945, the German navy had been seriosly persuing a "Soda Turbine" powerplant for use in it's high speed U-Boats. The Type-XIX (Type 19) class submarines were fitted with a Walthers steam turbine that used Hydrogen Peroxide in the same manor that the Soda Motors used Sodium Hydroxide. The experiments led to several disasterous results when the tanks ruptured and Hydrogen Peroxide scalded the crew. In the end, the same fate that befell the soda motor came to the peroxide turbine, it was abandoned in favor of the Type XXI, which had newly developed and improved batteries and motors. Electricity won out in the end.
Although the Soda Motor is an elegant system, one in which the exhaust heat is captured an reused, it is surprisingly inefficient. True, when simply using the soda to reabsorb the heat, it is many times more efficient than a conventional engine, it is when you go to get the soda back out of the water that you loose all of your efficiency. The only way to remove the water is by distilation, which means boiling the solution until all the water steams out. This takes far more fuel and heat than boiling the water did in the first place, so that after the whole cycle, you burn one and a quarter times the amount of fuel than you would in a conventional engine. Thus, without a specialized application for it, the soda motor could not compete with other forms of power.
The D&H experimental boilers are another interesting subject. They aren't really pure watertube boilers, but a hybrid of watertube firebox and firetube boiler. The engines that were equiped with them were built in D&H's own shops, because they were of a specialized design that other manufacturors were not interested in at the time. The firebox was a radical departure from the standard design. There was no crown sheet or side sheets, and no staybolts were used except for the backhead, which was of a conventional style. The front of the firebox had a normal boiler neck with a bulkhead supporting the firetubes. The sides and top of the firebox were lined with tightly packed rows of pipes with headers on the top and bottoms. The watertubes were in two curved banks, having a wishbone shape. All three headers were plumbed right into the forward bulkhead to connect with the rest of the boiler. The firebox had the grates, ashpan, and mudring of a normal firebox, and in that respect wasn't much different form any other boiler.
The watertubes in the boiler had many advatages to them, and the engines were relativly easy to maintain on the short run. With the use of tubes instead of plates and staybolts, assembly time was much shorter and with less obstrcution from the absence of staybolts, circulation was better. The round contours of the tubes also offered more surface area than the flat plates did. Because the tubes were in a virtical alignment, and had such strong circulation, they did not suffer from scale buildup nearly as much as regular fireboxes did. The top header, however was in a horizontal alignment, and it was especially prone to scaling. Other problems were also discovered quickly. With the absence of a crown sheet, the bottom of the upper header became the minimum water level. If water wasn't maintained in the header pipe, it would soon melt from it's exposed position high and dead center of the firebox, with a natural arch directing the heat straight for it. As the header pipe was position at about the highest point of the whole boiler, there wasn't much tolerance between overfilling and having to little water in the boiler. Another issue stemmed from the fact that since there was no crown sheet, they didn't think of putting fusible drop plugs in them at first. they did have them soon after their first experiments though, probably realizing that they needed them if they scorched the tubes once. Because they were subjected to such heat, pressure, and especially vibration and pounding of locomotive use, the joints were the pipes and headers connected often developed leaks and would regularly need to be replaced. The result was that the whole pipe assembly was pulled and re-milled just like the tubes and flues. The pipework is the most expensive and time consuming part of boiler work, and dirty watertubes weren't always a welcome delivery at the flue shop.
I'd also like to mention another famous watertube boiler, the 900psi Babcock & Wilcox water-tube "flash" boiler that was installed in N&W #2300 John Henry in 1954. This was the highest pressure boiler that I can think of being used in a US locomotive. The highest pressure boiler for a conventional steam engine in the US was also a watertube boiler, and a completely welded one at that. Built for D&H by Alco was #1403, the L. F. Loree; a superheated 4 cylinder compound 4-8-0 with a 500psi boiler and a Dabeg rotary-cam valve gear and Poppet valves. This switcher is the only streamline switch engine I've ever seen. They had to streamline it, for without the elegant shrouds this engine is the most grotesque monstrocity since C&A's "Monster" of 150+ years ago.
Keep up with those answers, we still got a few parts left!Matthew Imbrogno-Mechanical Vollenteer, Arizona Railway Museumhttp://www.azrymuseum.org/
PS: Stay tuned, pictures will be coming up next!
Mimbrogno wrote: It is interesting to note that while Soda motors had been all but abandoned by 1900, the technology would still intrigue inventors for decades. As late as 1945, the German navy had been seriosly persuing a "Soda Turbine" powerplant for use in it's high speed U-Boats. The Type-XIX (Type 19) class submarines were fitted with a Walthers steam turbine that used Hydrogen Peroxide in the same manor that the Soda Motors used Sodium Hydroxide. The experiments led to several disasterous results when the tanks ruptured and Hydrogen Peroxide scalded the crew. In the end, the same fate that befell the soda motor came to the peroxide turbine, it was abandoned in favor of the Type XXI, which had newly developed and improved batteries and motors. Electricity won out in the end.
The peroxide cycle made use of the exothermic reaction of 2(H2O2) -> 2H2O + O2. Additional energy was obtained by burning some diesel oil in the steam-oxygen by-product. These subs were capable of some very impressive underwater speeds, but the hazards of storing concentrated peroxide outweighed the benefits. In addition, a LOT of peroxide was needed to provide useful underwater range.
The Brits built a couple of peroxide subs after WW2, and also came to the conclusion that the problems with peroxide outweighed the benfits. The ultimate answer for submarine propulsion was nuclear.
The GE 'Turbomotives' built in 1939 used steam at 1500PSI, but performance didn't meet up with expectations. Main problem was that locomotives are not conducive to efficient operation of the condensers.
The June 1967 issue of Trains had an article on the D&H high pressure experimentals as the third part of the eveolution of 2-8-0's on the D&H. The 1403 was intended as a road engine, not a switcher.
1.a. mudring.....the base to which the inner and outer sheets would be attatched...... the "base"
b. backhead....... the rear sheets of steel thru which the firebox doors would be as well watercocks and glasses
c. crownsheet.....the upper sheets of the firebox where most "radial stays" would be....this area must be covered with water at all times or "boom"....this area also needs protection from the 2000 to 3000 degree temps....see brick arch
d. neck.....the front sheets that form the square to round shape of the firebox to boiler transition
2.a. syphon...is a bulbulous area of uppers sheets that are filled with boiler water to increase heating surface
b. circulators....forced air jets above the mudring to increase heating eff.
3 grates.....movable pieces of steel that appear "extruded" that allow air to pass thru the firebox and ashes to fall thru to the ashpan
4. brick arch......protechs the crownsheets from the abrasive nature of cinders...forces circulation of the hotgases and i have to cheat to see the third.....
5. burning oil is the obvious answer.........oil burners have no grates...or stokers....most oil burners will have steam lines to the tender to heat the oil
6. the opposite of firetube........the fire surrounds the tubes which are filled with water
bonus.......duplex im sure.....the other not so sure......i want to say worthington but.......
7. drop plug......i would guess a fusable plug in a staybolt that would blow steam or water if to high a temp is reached
8.......to the tune of "spoonfull of sugar".....a scoop of sand helps the soot go away the soot go away......a shovelfull or 2 of sand in a running engine blasts the soot loose........
9. i would guess its a wideopen thing.......johnson in the corner and notched out as far as she'll go
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