Belpaire Fireboxes

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Belpaire Fireboxes
Posted by SPer on Monday, April 23, 2018 1:25 PM

Did Santa Fe ,Southern Pacific,and Union Pacific had large and small steam locomotives built with Belpaire Fireboxes

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Posted by M636C on Monday, April 23, 2018 7:48 PM

In general, no...

Many older SP and UP locomotives were built to "Harriman Standards" which didn't include Belpaire fireboxes.

The main user of Belpaire fireboxes was the Pennsylvania railroad, followed by the Great Northern.

The Brooks Works built a lot of locomotives with Belpaire fireboxes, and they developed a design particularly for Belpaire Fireboxes with narrow grates (between the driving wheels) on 2-8-0s and some 4-4-0s and 4-6-0s.

This design was adopted by the British Great Western Railway and later by the London Midland and Scottish and even later British Railways. (So a design developed in the late Nineteenth Century was still being built up until 1958 or so)

The New York Central had a number of the locomotives from Brooks with these Belpaire fireboxes but never to the extent of the PRR. The B&O had two classes, a 4-4-2 and a 2-8-0 built to PRR designs and these kept their Belpaire fireboxes right to the end of steam.

Of course, the PRR had locomotives without Belpaire fireboxes, the J-1 2-10-4s being the most notable example in the later years.

Peter

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Posted by ruderunner on Saturday, April 28, 2018 7:07 PM

Since I'm not much of a steam guy, what is a Belpaire firebox?

Modeling the Cleveland and Pittsburgh during the PennCentral era starting on the Cleveland lakefront and ending in Mingo junction

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Posted by Overmod on Saturday, April 28, 2018 7:46 PM

ruderunner
Since I'm not much of a steam guy, what is a Belpaire firebox?

The other great steam-locomotive innovation from Belgium (along with Walschaerts valve gear).

Familiar from many classes of PRR power, this is the style of firebox with the 'hip' corners and relatively flat side sheets.  It has the nominal advantage that, unlike the usual kind of radial-stay firebox, most of the staybolts can be of common length, which was a bit more of an advantage in the era that thought of the waterspaces around the firebox as insulation rather than enhanced steam-generation capacity (to optimize the latter, the legs need to taper wider as they approach the crown, to make room for nucleate boiling in the absence of mechanical steam separation)

Wikipedia actually has a pretty good introductory explanation

Lima, toward the end of big steam, extended the general principle to the combustion chamber of a modern boiler, and then made the lower 'legs' of the chamber symmetrical with the upper (giving some additional tube and flue room in the 'corners' thus formed).  This they called the 'double Belpaire' design, and it would likely have been applied to any of the 'long compression' designs Col. Townsend was trying to sell at the end of the '40s.  (As an aside, the design would likely have limited driver diameter to 76" for reasonable East Coast clearances.)

 

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Posted by wjstix on Sunday, April 29, 2018 10:52 PM

ruderunner

Since I'm not much of a steam guy, what is a Belpaire firebox?

 

 
Short answer - the firebox is the area just in front of the cab where the coal or oil is burned to heat the water into steam. On most steam engines, that part of the boiler is round (radial) just like the rest of the boiler. On an engine with a Belpaire firebox, it's squared off and is noticeably different from the rest of the boiler.
 
You can see how the Belpaire firebox sticks up near the cab in this video on Pennsy K-4 Pacifics:
 
 
Stix
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Posted by M636C on Monday, April 30, 2018 7:45 PM

wjstix
 
ruderunner

Since I'm not much of a steam guy, what is a Belpaire firebox?

 

 

 
Short answer - the firebox is the area just in front of the cab where the coal or oil is burned to heat the water into steam. On most steam engines, that part of the boiler is round (radial) just like the rest of the boiler. On an engine with a Belpaire firebox, it's squared off and is noticeably different from the rest of the boiler.
 
You can see how the Belpaire firebox sticks up near the cab in this video on Pennsy K-4 Pacifics:
 
 

 
The word "radial" refers to a pattern of stays between the inner and outer firebox. Many round top fireboxes have direct staying just like a Belpaire. In a round top, all the vertical stays are of different lengths and this imposes varying stresses on the the firebox sheets as the boiler heats and cools.
 
While radial staying works well with all steel boilers, it becomes a big problem with copper inner fireboxes owing to the different coefficents of expansion of copper and steel.
 
Two classes of Australian locomotives, the New South Wales "C36" 4-6-0 of 1925 and the Victorian "S" 4-6-2 of 1928 used radial stayed round top fireboxes with copper inner fireboxes.
 
Interestingly, both systems had used Belpaire fireboxes with direct stayed copper inner fireboxes on most locomotives built during the 20th Century to that time.
 
The Victorians got the message first, and luckily there were only three S class. A fourth was built with a steel inner firebox and the others modified to match. On the other hand, the S class had Gresley conjugated valve gear and remained a maintenance headache for their whole lives (until 1954).
 
New South Wales were slower to change, not least because there were 75 "36 class". Leaving nothing to chance, the fireboxes were all rebuilt with steel inner fireboxes and direct staying from 1934. With such a large class, they painted the rebuilt locomotives green instead of black so that you could tell before putting one on an important train. This design had all the problems of the direct stayed round top, and in the early 1950s, new Belpaire boilers were fitted.
 
Since copper inner fireboxes were common in Europe until the Second World War, the Belpaire firebox proved to be a lower maintenance option than the direct stayed round top, particularly in the UK.
 
Peter
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Posted by wjstix on Sunday, May 13, 2018 10:44 PM

ruderunner

Since I'm not much of a steam guy, what is a Belpaire firebox?

 

 
I forget about this image, right under my nose. Embarrassed Anyway, it's a good pic of a Pennsy engine. Note how the boiler right in front of the cab is kinda 'squared off' instead of round like the rest of it - that's the Belpaire firebox.
 
 
Stix

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