I am not being sarcastic, nor critical, but I have some dificulty believing that a Cab Forward would have its crown sheet compromised on a 2% grade mainly because of the grade itself! If we suppose that its total boiler length was approx. 35’, then 2% over that length is merely 8 1/2", hardly a catastrophic change in level. Am I missing something…what do I not understand?
Again, I am interested in this subject, and just want to understand.
Have a look at Figs. 2 & 3 in this document
It shows that the crownsheet is towards the top of the boiler (and hence near the surface of the water), so an 8.5" change in water level is significant. On our preserved Pacifics the water glass tube is only about 6" long and at half glass on level track the water is about a foot above the crownsheet.
btw, a 35’ boiler sounds a bit short for a Cab forwrd, I’d say they were a lot longer than that, given that they were big articulated locos. Perhaps someone can provide the actual boiler length (barrel + firebox)
Did it make a difference if the locomotive had a Belpaire firebox ?
Wow,
Thanks everybody for a wonderful education, especially Overmod—not to dimini***he significance of other contributors.
Just a few comments:
(1) In case there is someone associated with this operation, I am not going to name it and enrage them. But, once I was in a stopped light Mikado that was in a siding for the night with its fire lit for an excursion on the following day. They had a 12-year old watching it for the night. Granted, there might be 100 reasons why this is perfectly acceptable and causes no need for concern that my limited technical knowledge can’t comprehend. But, like I say, I am a lawyer, and my first instinct is to look for liability. Overmod’s “intelligent” fireman doesn’t seem to be always available. Not to knock the 12-year old either, and I am sure he knows more about steam than me; but that scared the hell out of me.
(2) Dropping the fire does happen occasionally. I remember reading a story about the mechanism that greases the driving rods failed on a Hiawatha (at 100mph!). The driving rod froze and literally lifted the Pacific off the ground with each revolution. Remarkably, the locomotive stayed on the tracks, but the first thing the engineer did was dump the fire.
Thanks everyone,
Great discussion.
Gabe
Nanaimo brings up a point I’ve been wondering about: what is the difference between a Belpaire firebox and the ordinary kind? I know it is distinguishable from the outside by the “shoulders” at the top, but what are they caused by?
Got it, Hugh, and thanks. It all makes sense…scary sense.
Didn’t the “Standard Railroad Of The World” adopt the Belpaire firebox to get away from using flexible radial stay bolts? I’ve never studied the the actual engineering aspects of the Belpaire but I believe the advantage was to avoid the use of the leaky staybolt caps and resulting maintenance hassles that the more common conical connection boiler had? All of this discussion is fascinating and the one thing that has to be considered in locomotive boiler design is that the firebox necessitated using FLAT sheets. Like the crushing egg theory, a cylindrical enclosure is able to withstand much greater pressure than a flat surface… hence the staybolt.
G’day, Y’all,
I always heard that firemen started to get indigestion when the water level got down to half full. They knew the consequences of an empty tank. What I don’t understand is why it took management until nearly the end of steam operations to realize how much simpler life was when they coupled a tank car behind the tender and pumped water forward to the tender. It meant that the train did not have to stop at every water tower to give firemen indigestion relief. Some of the later steamers went through 10,000 gallons in about an hour.
Jock Ellis
Cumming, GA US of A
Mr. Ellis,
I am far from an expert in such matters, but my bet would be the reason it took so long for railroads to do this is the lack of power of early steam locomotives.
A tank full of water is a lot of weight–probably several times more than your average reveune loaded car of the time. When you were dealing with underpowered steam locomotives to begin with, one could understand the reluctance to reduce the revenue tons a locomotive would be capable of carrying by attaching the such a heavy car.
As super-power steam came on the scene, a tank load of water represented a lower percentage of the locomotive’s revenue pulling capabilities and made it more acceptable.
That is just my bet, good question.
Gabe
…As a youngster I rode my bike about 4 plus miles to see the results of a boiler explosion on the B&O on the S&C branch {Somerset, Co., Pennsylvania near Listie. Time frame was about 1943…The remaining parts of the sizeable locomotive were the frame, steam cylinders, wheels and rods…and not much else…! The cab and boiler were non existent. In remembering I believe it was still on the rails.