I think most smokebox doors can be (theoretically) opened and closed by one person. On American locos, there's the two-pin hinge and a ring of dogs. On the common British version I showed above, it's the two-handle T-bar thingy--just undo it. So I don't think the French version is especially noteworthy on that account.
Looking at the design of the Y in the above photo, I do see what looks like a pressure plate behind the center of the Y. I wonder if this design isn't a hybrid of the British and the American versions. The center of the "dome" would be pressed in via the strap metal of the Y when you tightened the single clamp over on the left side, at the base of the horizontal Y. Then you tighten the remaining dogs. I note that there are fewer of them than on a typical American version.
I went over and looked at how the Germans do it. There are a goodly number that do it the American way, though it seems with fewer dogs. BUT. There are also many that have both the dogs and an obvious center draw-down reminiscent of the French method.
Ed
Doesn’t the ‘sideways Y’ allow a single mecanicien or whoever to open the door and then close and align it by himself, before flipping those bails or crabs or whatever you call them around the outside that clamp the edge of the door down? That’s kinda what I thought it was for, anyway.
I think describing Ed's youthful recollection as a "French system" is going a bit too far. If one goes online and examines examples of French steam, the "system" that is most common would appear to be one similar to ours. That is, there is a hinged door with external dogs.
Below is an example of a typical installation. The French, wanting to be French, added a "sideways Y" to many of their designs, as can be seen in the photo.
Here is the thing: a smoke box door, particularly on a non-self-cleaning smokebox, HAS to seal reasonably tightly or some of the induced draft will be wasted or spoiled, and unwanted heat developed where it will not benefit anything.
North American practice does this with the ‘plurality’ of lugs or crabs secured by bolts; you see this even in something like a Selkirk or Y6b-with-oval-door where the actual “door” is very small. Part of this choice might relate to the layout of a Master Mechanic-style gas path which is much more aerodynamically (technically ‘gasdynamic’ but we’re all friends here) complex than most realize, instead of what the normal British engine will have.
Approximating this seal with the T-style locking bar and nutted wheel or lever appears to me to be using the ‘doming’ of the door as a kind of Belleville-like spring so the outer edge self-locates and warps into contact as it is loaded down. That is a reasonable approach IF you design your door and edge seat, and perhaps more importantly the seat at the center of the door where the clamping pressure comes on. It can in theory also provide some preload against heating expansion, and of course it weighs less than having an outer plate on hinges and secured to the smoke box wrapper with a ring of bolts, to access tubes and headers, suitably strong to hold all the lugs for the inner door.
The French system is for designs that can’t or should’t provide a strut right in the gas path for a MM type box, but lock to the inside of the rim with extending bars. That system would provide dubious sealing at best unless you have an acting fulcrum on the bars so you can force the outer ends or dogs against the inner rim and thereby force the door into seal. Look for fun when heat warps the bars or linkage while they are screw-clamped and you expect easy retraction when clamping pressure is relieved! Obviously the more bars, the better the seal that can be made and the lighter the door can be (this of much more potential value in a world with 16t or lower permissible axle load even for large express steam locomotives) but also the more bars, the more complexity and first cost and weight. Hence the number of bars vs. door thickness will be something worked out by the designer and then tweaked as necessary by the shed people.
I have always thought that the combination of evolved MM principle and self-cleaning in this country largely relieved the need for a quick way into the smokebox. (As a historical note, the “predecessor” approach was to provide a pocket or hopper under the front of the smokebox, which you can see in many drawings of turn-of-the-20th-century power, and if self-cleaning arrangements become infeasible for use in future (e.g. excessive ‘particulate emission’ onto the wayside in general) some sort of front-end dumpable containment may again become desirable.). England was also the happy home of many locomotives with fixed grates, which required someone wriggling into the often cramped firebox through the firehole door and then passing ash out the door by hand (!). In a world where that is SOP, it isn’t surprising that frequent manual shoveling-out of cinders would also be done, and a door arrangement facilitating it desirable. But on North American power it was largely an affectation, and not particularly well-suited to what was going on just inside them...
7j43kThe French tend to get carried away with their engineering.
Oui.
Speaking of looks funny, I just noticed the bell yoke turned 90° to the boiler on the 5600. Now, how often do you see that?
The French tend to get carried away with their engineering. And sometimes they pull it off beautifully. See: Eiffel Tower, for example.
7j43kI fully admit I could be wrong about the internal dogs. I'd love to see how they pulled it off. And I still think it a stupid idea if they did it.
IF, and that's a big if... I recall, I saw it years ago on a small tank locomotive that was in a museum near Akron, Ohio. I was very young at the time. I now also recall someone mentioning that the engine was French.
The inner lever was attached to a disk inside the smokebox door. Around this disk at 90° intervals were rods which extended to four points around the circumference of the door. When the door closed and this disk rotated the four rods extended to engage the inner lip of the smokebox front.
When the second, outer wheel was turned it (again IF I recall) extended the disk IN toward the flue-sheet which had the effect of tightening where the rods engaged the lip of the smokebox front.
I could probably make a sketch if my written recollection does not suffice.
Maybe it was a one-of-a-kind apparatus. Maybe it was done to correct a poor-fitting smokebox door. This locomotive was very small, the door was perhaps 24" in diameter. I only mentioned it so the OP could have a broader understanding of steam locomotive construction and the many variables involved.
Hope that helps.
Regards, Ed
Overmod Probably better said: when the engine came ‘off shed’ from overhaul both handles would be set to point down.
Probably better said: when the engine came ‘off shed’ from overhaul both handles would be set to point down.
I'm looking at a photo captioned "Front view of No. 70004 WILLIAM SHAKESPEARE in exhibition finish for the Festival of Britain, 1951." I doubt you could get more 'off shed' than that. Only one handle is pointing down.
Now I'm looking at that same engine with the smokebox door open.There are no dogs around the inside edge of the door--it is very plain. There appears to be a rod with a "T" end coming through the center of the smokebox, and there is a post in the smokebox with a horizontal slot that would receive that T. So, with the door open, you place the "inner" handle at 9 or 3 o'clock and shut the door. With proper planning, the T goes through the slot. You turn the inner handle to 6 o'clock. It will be loose. You start turning the outer handle on a threaded shaft. This draws the T tighter, which thus clamps the smokebox door shut. I have seen some photos where this outer handle is replaced by a wheel. More symmetrical, less leverage.
I don't doubt that there MIGHT have been a policy somewhere that said the draw-down handle should be 6 o'clock sometimes. But that would not be best practice, as it would limit the options on how much closing pressure the door should have. It's PR winning over Engineering.
Now to the B&O locomotive. I note that the inner handle is NOT pointing down. Almost surely, the door has been opened at some time during the display period; and it has not been properly secured. Yet. OR. They have a very different system of locking. That looks JUST LIKE the British style. Co-incidentally.
I will disagree with other-Ed's statement that there were multiple internal dogs (I believe that's what he said) because it would expose numerous moving parts to heat and corrosion, when there is a much simpler and more reliable and durable way to do it, as demonstrated by the Brits.
I fully admit I could be wrong about the internal dogs. I'd love to see how they pulled it off. And I still think it a stupid idea if they did it.
Now, most British locomotives don’t, I think, have effective or aggressive self-cleaning screens, so people would be into that smokebox fairly often, probably with things nice and hot. Wouldn’t take much distortion to get the latch binding, or much screwing to seal a distorted door to get the handle off to the side. The thing that queered the last test run of Bulleid’s Leader was reported as the door being left open to the point glowing char was dribbling on the deck; the door being so highly distorted by then the testing was stopped (as it turns out, forever). And at that point who knows what time those two handles would be showing?
So if modeling ‘as intended’ keep ‘em at least close; if in ‘real service’ ... just as Ed sayeth.
Overmod As these were originally intended (and you can see this in many early pictures of this engine and other B&O power with them) both handles would be together pointing straight down.
As these were originally intended (and you can see this in many early pictures of this engine and other B&O power with them) both handles would be together pointing straight down.
Interesting idea. I've just been looking at lots of photos of British locomotives with this locking system, and they rarely both point down. You'd think the Brits would know better.
As these were originally intended (and you can see this in many early pictures of this engine and other B&O power with them) both handles would be together pointing straight down. There will be a story behind that particular trip! It appears to me that the door might not even be correctly dogged, with only the relative smokebox vacuum holding it shut; if that is so air leaking around the edge might be rousing any residual char or ‘sparks’ in the self-cleaning front end to a nice, blistering, warping heat ...
Ohhhh okay, thanks all!
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Many European engines have smokebox latches like this. Not many North American locomotives had these.
Handles for securing the smokebox door.
Dave
Just be glad you don't have to press "2" for English.
http://www.youtube.com/watch?v=zQ_ALEdDUB8
http://www.youtube.com/watch?v=6hqFS1GZL4s
http://s73.photobucket.com/user/steemtrayn/media/MovingcoalontheDCM.mp4.html?sort=3&o=27
Rather than the usual practice of using external dogs with threaded nuts which hold the smoke box door closed, and gas-tight, in this arrangement, the inner lever operated internal dogs which acted something like the lock pins on a bank vault door. Some were a simple "dart" which engaged a slot in a cross-bar.
The outer lever was simply a locking screw which also pulled the dogs tight to form the seal.
B&O had several "experimental" engines designed primarly by George H. Emerson (the name on this 4-4-4-4 in your photo). These had water-tube boilers. Emerson may have been influenced to use the primarily British design to simplify the look for a "cleaner" front end and perhaps got the idea when the locomotive King George V. was displayed at B&O's Fair of the Iron Horse in 1927.
http://www.american-rails.com/n-1.html
Hi, what does the 2 pins on the smokebox front of this B&O 4-4-4-4 do?
They're set to different positions in different pictures.
It looks funny...looks like a clock on the front of the engine!
Thanks!
Charles