| Railway Preservation News https://www.rypn.org/forums/ |
|
| Locomotive Boiler Capacity - US vs. German https://www.rypn.org/forums/viewtopic.php?f=1&t=32871 |
Page 1 of 2 |
| Author: | M Austin [ Sun Feb 12, 2012 3:22 am ] |
| Post subject: | Locomotive Boiler Capacity - US vs. German |
Much ado is made about the work of Professor Tross to limit pandemic staybolt breakage in German steam locomotives. Perspective as to the relative size of the boilers is revealing. It is important to note that US locomotives are typically radially stayed, whereas German locomotives have square fireboxes with flat crown sheets. Historically the boilers were designed for copper fireboxes and steel was supplanted due to scarcity, due to war, etc., without significant design changes. Design attributes of German boilers, identified by Prof. Tross, not applicable to most US locomotive boilers: Crownsheet Sagging Side Sheet Cracking Firebox Bulging The most prolific class in Germany is the 50 & 52 of which over 10,000 were produced. The steaming capacity of the boiler is approximately that of a Rio Grande narrow gauge K-36. The closest thing to SuperPower in Germany is the Class 44 3-cylinder 2-10-0. The boiler however, has a steaming capacity closest to the Union Pacific P-77 series 4-6-2 such as #3202 (vintage 1905) in Portland, OR. Class______ Wheel_________Quantity____Grate_____Evaporative_______Boiler __________Arrangement______________Area______Heating Surface____Pressure ___________________________________(Sq. Ft.)___(Sq. Ft.) GR 50 ........ 2-10-0 ........... 3000+ ....... 41.9 ......... 1,914 ................ 235 GR 52 ........ 2-10-0 ........... 7000+ ....... 41.9 ......... 1,914 ................ 235 US K-36 ...... 2-8-2 ............ 10 ............ 40.0 ......... 2,120 ................ 195 GR 44 ........ 2-10-0 ........... 2000+/- ..... 49.0 ........ 2,558 ................ 235 3-cylinder US P-77(UP) .4-6-2 ............. 133 .......... 49.5 ........ 2,567 ................ 200 UP #3202 Class 50 Information Class 52 Information Class 44 Information |
|
| Author: | Frisco1522 [ Sun Feb 12, 2012 8:42 pm ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
Matt has posted what I've always thought. The European engines compared to ours is like comparing a watch to Big Ben. I never thought their engines were built for the heavy service that American engines were. I've often said that some of our tenders were as heavy as some of the trains they hauled. I'm going to go hide under the desk now. |
|
| Author: | whodom [ Mon Feb 13, 2012 10:00 am ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
OK, but how does that relate to the ability of Tross staybolts to reduce staybolt breakage in typical U.S. large locomotive boilers? |
|
| Author: | Frisco1522 [ Mon Feb 13, 2012 10:47 am ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
I thought Matt covered that pretty well in his post about the design of the boilers vs ours. |
|
| Author: | G. P. Bensman [ Mon Feb 13, 2012 12:27 pm ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
To quote Cousin Vinny - " Sooooo have the laws of physics been suspended in your (U.S.) boiler and apply only in a German boiler?" U.S. boilers are much larger and move more - but in the same directions in the same amounts per inch. Really? What? Let's try to learn why the Flannery Bolt Company translated all of Mr. Tross' work to English in 1952 and presented it to the Master Boiler Maker's Association. Come out Don! |
|
| Author: | Doug Debs 2472 [ Mon Feb 13, 2012 3:14 pm ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
European steam locomotive boilers were often worked very hard. But European maximum allowable axle loads were and are much lower than in the USA. 15 to 20 metric tons (about 33,000 to 44,000 lbs) is common for mainline steam power built 1920s-1960s. Comparable engines in the USA ranged from 55,000 to 75,000+ lbs per driving axle. So the largest European steam loco boilers tend to be about the same capacity as medium-sized American ones. For example, the 1,340 2-8-2 locomotives built in 1945-1947 by Baldwin, Alco, Lima, Montreal, & Canadian Locomotive Works to rebuild the war-devastated French national railways (SNCF 141R class) are a compact tight-clearance design based on an updated USRA 2-8-2A (light Mikado), especially the Green Bay & Western 2-8-2s. Driving axle load is 20 long tons (about 44,000 lbs). The later 141R deliveries had roller bearings. They're impressive mainline excursion engines. See http://en.wikipedia.org/wiki/SNCF_Class_141R and http://www.martynbane.co.uk/france/lemistral07/141r.html - Doug Debs |
|
| Author: | filmteknik [ Mon Feb 13, 2012 7:29 pm ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
So there's 17 141R's on the bottom of the ocean off Newfoundland. Hmm. LOL Steve |
|
| Author: | Frisco1522 [ Mon Feb 13, 2012 8:41 pm ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
Hey, I just said it was my opinion. Your mileage may vary. German boilers grow in MM. 8!) I'm back under the desk now. |
|
| Author: | Robby Peartree [ Tue Feb 14, 2012 2:08 am ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
The amount of deflection in the boiler, like most things, is proportional to its size. So what works in a smaller boiler may not work in a larger one. Therefore when comparing standards between Europe and the US one should consider among many issues is the relative boiler size. Is there some more room under the desk? Robby Peartree |
|
| Author: | whodom [ Tue Feb 14, 2012 6:49 am ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
Robby- I follow your logic. But if a Tross stay is less prone to breakage in a small German boiler, shouldn't it make even more sense to apply them to a U.S. boiler that deflects more? |
|
| Author: | Dave [ Tue Feb 14, 2012 10:20 am ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
Let's not lose sight of the forest for the details of the trees. Previous threads have covered the larger design concept differences between common German (balloon boiler)and US practice. The German approach was to accept and absorb deflection as an inherent part of how the overall boiler was considered and built, ours was to control and minimise it, if I am understanding it correctly. So, if we take a US style heavy rigidly mudringed boiler and replace some of the rigid stays with Tross stays instead of flexis in the "breaking zone", are we making a better, more robust rigid boiler or allowing the stresses to just migrate further before being controlled? Sure, the origination of the stresses is the same, but it is the ramifications of the potential differences in the reaction that I'm thinking about. So, is it right to think of Tross stays as simply another rigid stay design that just handles stresses by dispersion rather than concentration, or by doing so do they allow for greater or differently reactive movement in the steel the stays are staying in the first place? dave |
|
| Author: | mjanssen [ Wed Feb 15, 2012 3:28 pm ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
Dave, It is right to think of Tross stays as simply another rigid stay design that just handles [bending] stresses by dispersion [across the staybolt shaft] rather than concentration [at the sheet, or fulcrum of the bending.] The Tross stay does not necessarily make the rear boiler more rigid, but because the staybolts can handle more bending stress before actually permanently bending, the rear boiler tends to return to its original shape when the stresses (fire induced, shrinkage induced) are removed. When the rear boiler can better retain its designed shape, it can better retain its designed pressure. It was more practical for the Germans to engineer lightly-built boilers to handle higher stresses than rebuild the railroad infrastructure for heavier boilers. As we helped rebuild the French infrastructure, certain districts in France could handle the 141R, which Chapelonized, is a very impressive locomotive indeed, and BTW, has a pretty chunky mudring. The quality of heating surface and quality of the combustion and drafting systems have a lot to do with boiler capacity. It is interesting to note that German boilers have a lot of superheater surface and put out some very hot steam. Many locomotives are Lentz poppet valve or nifty piston valve, and have some pretty good steam rates per/hp. There is nothing impressive about a locomotive which is provided so large a boiler it cannot be run out of steam no matter how inefficiently its steam engines are operated. |
|
| Author: | mldeets [ Fri Feb 17, 2012 2:53 am ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
So is it all boiling down to "Size Matters"? Any room left under that desk?......mld |
|
| Author: | whodom [ Fri Feb 17, 2012 9:59 am ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
mldeets wrote: So is it all boiling down to "Size Matters"? Any room left under that desk?......mld I believe that's a reasonably accurate paraphrase of Matt Austin's original post, while a similar paraphrase of Matt Janssen's would be "it's not the size of the ship, it's the motion of the ocean". :-) |
|
| Author: | Dave [ Fri Feb 17, 2012 10:37 am ] |
| Post subject: | Re: Locomotive Boiler Capacity - US vs. German |
From a practical POV, the majority of museum and tourist operators run power that is comparable in size to European standards, so, if we're thinking practically rather than theoretically, for most of us there's not an issue about size as much as construction comparisons to be made. If I'm replacing a firebox on, say, a 50 ton prairie in the US, retaining the heavy mud ring and thick wrapper sheet, I'd want to know if it would make sense for me to spec and engineer Tross rather than straight rigid stays since it takes the same amount of welding to install either. The deciding factor for me would be lifetime economy and robustness, remembering that the most expensive train you sell is the one you can't run because your locomotive is down. If Tross stays reduce the impact of stress cycles on the entire assembly, I'm interested. If they reduce stay breakage but increase knuckle cracking or tube loosening, maybe not so much. dave |
|
| Page 1 of 2 | All times are UTC - 5 hours [ DST ] |
| Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/ |
|