With the restoration of UP 4014, the weight of the Big Boy at 600 tons has been thrown around an awful lot. I was long under the impression that this was the weight of a fully serviced locomotive (boiler full of water; tender full of fuel and water). If this is true, than 4014 in its current "dry" state would be substantially lighter than that (not to take away from its undoubtedly substantial heft!). Just curious if anyone has any definitive info as I haven't been able to locate any.
You're right, of course, the 600 tons includes the 100+ tons of water and 28? tons of coal on the tender and the water and sand on the engine. Never seen anybody try to calculate the volume of water in the boiler, but seems like you could make a good guess at it.
According to Wikipedia, the boiler is 95 inches in diameter; another site indicates that it is 65' 5" long. That calculates to a volume of a little more than 24,000 gallons (assuming 231 cubic inches per gallon). In other words, just under 100 tons of water in the boiler (assuming 8 lbs. per gallon).
In round numbers then, assuming a fully serviced Big Boy is 600 tons even, if we subtract 200 tons for water in the engine and tender, and 25 tons for coal, it would appear a "dry" Big Boy would weigh in the neighborhood of 375 tons. That still makes its rolling across two-by-x lumber and sheets of plywood in the LA Fairgrounds parking lot pretty darn impressive!
kenotrainnut According to Wikipedia, the boiler is 95 inches in diameter; another site indicates that it is 65' 5" long. That calculates to a volume of a little more than 24,000 gallons (assuming 231 cubic inches per gallon). In other words, just under 100 tons of water in the boiler (assuming 8 lbs. per gallon).
I think there is something wrong with that calculation. The data plate for UP 4023 (the Big Boy at Omaha) indicates water capacity is 25,000 gal. I assume that is the capacity of the tender, and it is in the range of the tenders other large locomotives -- UP 844 is 23,500 gal, MILW 261 is 20,000 gal, CP 2816 is 12,000 gal and NW 611 is 20,000 gal.
I was staying out of this, but:
Relevant measurement for convection section is between front and rear tubeplates (get them off a dimensioned locomotive elevation, not Wikipedia - FedEx Kinko's can print one at large scale if you don't like working from a computer-screen image...) Smokebox does not contain water.
Convection section is full of tubes and flues, is not cylindrical, is not full 'up to the top', and I expect the reported diameter is OD, not ID.
Firebox and chamber water spaces (less volume occupied by staybolting, etc.) including volume over the crown sheet, are included in the water requirement.
I suspect the fill volume for the boiler was empirically determined rather than calculated -- has anyone asked Wes Barris if he has, or can obtain, a number? You might also "deduce" it from the vertical alignment of the axis of the piston rods relative to main-driver centerline (probably about 2") -- this is present for the same kind of mechanical reason the curve of a suspension-bridge deck appears exaggerated before the road decking is applied; with a full boiler the springs will settle 'just enough' to align things...
Overmod Convection section is full of tubes and flues, is not cylindrical, is not full 'up to the top', and I expect the reported diameter is OD, not ID. Firebox and chamber water spaces (less volume occupied by staybolting, etc.) including volume over the crown sheet, are included in the water requirement.
That's an excellent point! I didn't think about the volume "removed" by the tubes and flues, staybolts, etc. It's safe to say that when I made my calculation, I made a lot of assumptions and rounded a lot of numbers.
timz You're right, of course, the 600 tons includes the 100+ tons of water and 28? tons of coal on the tender and the water and sand on the engine. Never seen anybody try to calculate the volume of water in the boiler, but seems like you could make a good guess at it.
The tender capacity was said to be about 34 tons after the coal boards were added in late 1948.
CZ
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