[#offtopic] I hope the ‘purists’ in the crowd will forgive me! [:-,] The last couple of days; The Beyer-Garrett Locomotive thingy has been driving me crazy [swg]
The appearance of the NSWGR #6029 really ‘kicked it off’ for me. My comparison Thread between the afor-mentioned, Australian Big [4-8-4+4-8-4 ] Garratt Locomotive ,and UPRR BIG BOY [4-8-4]. Got my research brain cells to working. [Thanks to my friend Mike-Wanswheel!].
That tale of a Garratt locomotive in Texas really got me into it! I knew I had seen it, only WHERE? The following link is to a photo of it. [credited on photo]
It is a metre gauge Garratt from South Africa [ClassNGG13-#50 ] a 2-6-2+2-6-2
Operating on the PRIVATE ESTATE At Hempstead,Tx. [Special Note: Owner wants no uninvited visitors, and is known to tote a shotgun to greet those ignoring his privacy!]
A Garratt in a private collection in Texas? You know, I’m really not too surprised. There was a Texas oil millionaire named Connie Edwards who had a hanger full of Spanish-built Messerschmitts, if you’ve seen the movie “Battle of Britain” you’ve seen the planes. Whatever became of them I don’t know as I believe Connie’s passed on by now.
Who knows what else is hiding in barns and hangars down there? [^o)]
Good luck to that Texan who owns the Garratt, whether he allows visitors or not!
But you know, time keeps marching on. It’ll surface on the used locomotive market someday.
Getting back to Connie Edwards, while making “Battle of Britain” he was asked by an aviation reporter what it was like flying one of those Spanish Me-109’s. His answer floored the reporter:
“Well, it’s kind of like making love to a gorgeous redhead, while your wife is watching you!”
New horizons: Sam misspells ‘Garratt’ and then has the temerity to criticize misspelling it later in the same post. [:-,][:-,]
Alco of course wouldn’t have proposed a ‘Mallet-Garratt’ because that would imply compound working; in any case that was Beyer-Peacock’s idea in the mid-Thirties (which I remembered being covered in Trains, with a very funny cartoon later in the issue showing the thing negotiating double crossovers). About the largest thing they contemplated was the equivalent of double ‘Mikado-and-a-half’ or 2-6+6-2 (as Le Massena would quote Wiener) -
Note that this is very likely as much single-unit power in a scaled-up simple-articulated version as a single boiler ought to be made to produce; compare the actual HP curve of the Big Boy with its Challenger-style firebox to that of an Allegheny. You would use some conbination of antislip systems in practice but those are trivial to implement.
For a large standard-gauge engine the boiler dimensions involve the ‘best’ of three worlds within typical Eastern loading-gage limits: a deep firebox without truck structure under the grate and involving ash handling; a greater number of tubes and flues in the larger convection-section diameter but still limited in length to ~20’; good vertical steam separation to permit higher filling of the convection boiler and higher mass flow of generated steam without priming and carryover problems. I think it is likely that a large ‘North American’ Garratt would have extensive economization a la Franco-Crosti, probably carried in the cradle structure under the convection section, together with Cunningham-like circulation and some form of combustion-air preheat.
The principal issue with a weaponized double-Big-Boy (which you will notice is already ‘overkill’ for North American practice, 2-8+8-2 with high-speed pony trucks doing the necessary guiding jobs just fine, weight management becoming a criti
New horizons: Sam misspells ‘Garratt’ and then has the temerity to criticize misspelling it later in the same post.
Alco of course wouldn’t have proposed a ‘Mallet-Garratt’ because that would imply compound working; in any case that was Beyer-Peacock’s idea in the mid-Thirties (which I remembered being covered in Trains, with a very funny cartoon later in the issue showing the thing negotiating double crossovers). About the largest thing they contemplated was the equivalent of double ‘Mikado-and-a-half’ or 2-6+6-2 (as Le Massena would quote Wiener) -
Note that this is very likely as much single-unit power in a scaled-up simple-articulated version as a single boiler ought to be made to produce; compare the actual HP curve of the Big Boy with its Challenger-style firebox to that of an Allegheny. You would use some conbination of antislip systems in practice but those are trivial to implement.
For a large standard-gauge engine the boiler dimensions involve the ‘best’ of three worlds within typical Eastern loading-gage limits: a deep firebox without truck structure under the grate and involving ash handling; a greater number of tubes and flues in the larger convection-section diameter but still limited in length to ~20’; good vertical steam separation to permit higher filling of the convection boiler and higher mass flow of generated steam without priming and carryover problems. I think it is likely that a large ‘North American’ Garratt would have extensive economization a la Franco-Crosti, probably carried in the cradle structure under the convection section, together with Cunningham-like circulation and some form of combustion-air preheat.
The principal issue with a weaponized double-Big-Boy (which you will notice is already ‘overkill’ for
It’s only 70 bucks and change from Betexa, too. Buy two and you can make your own ‘Mallet-Garratt’ for display… if you have a wall long enough!
We on the steam_tech group took a leaf from the Spartacist playbook and made it a point to ALWAYS correct misspellings of Herb Garratt’s name. It is a matter of principle, not Writing-to-Read local option. I got one former poster here upset by making the claim a bit too forcefully, thinking that he would recognize the tongue-in-cheekiness of it… thinking wrongly, as it turned out.
Keep in mind that Garrett is a famous name in United Stated practice in a number of respects, turbocharging in particular, so there is little surprise the spelling looks familiar. It’s just not the right spelling of the locomotive inventor, just as the spelling of the hamburger chain isn’t correct for wanswheel’s IRL identity…
I chuckle at this very-large-Garratt business in part because I designed one of the things, complete with the necessary alternate history that would justify building and operating a fleet of them. The elevation drawing occupied pride of place in my high school’s English AP classroom… until it was STOLEN a couple of years later; it is interesting to think that someone out there still has all 14-odd feet of it for potential rediscovery.
We need to preface the discussion by noting that the Triplexes were not exactly ‘failures’ of necessity; even had they been given an appropriately-proportioned deep firebox and chamber, and a proper multinozzle front-end arrangement, they would have succeeded in sustaining ‘drag’ operations greater than the draft gear of the day would likely have tolerated for long. Even adapting a Challenger-style arrangement would likely have worked. The arrangements for water distribut
This 2-8-8-6 configuration I’ve seen mentioned in other topics before. The 6 wheel trailing truck implies the firebox is situated entirely over the trailing axles much like the C&O H-8 2-6-6-6 (correct me if I’m wrong), and is thus situated further back compared to a firebox partially situated on top of the drivers. So in this imagined “2-8-8-6” design, how long are the tubes and flues meant to be? (given that the H-8 was already at the upper end with 23’ long tubes). I’d expect the length to be made up with a very long combustion chamber, but how long? Now I know both Ralph Johnson’s The Steam Locomotive and a Mechanical Advisory Committee report of 1935 praises the combustion chamber and offer few caveats (it lowers the surface to volume ratio of the firebox, increases direct heating surface area and can be used to make up extra boiler length to permit practical tube lengths). However, as Ralph Johnson also mentions, the more heat absorbed in the firebox, the less is available for superheating in the tubes. Therefore, just how long can a combustion chamber practically be?
I believe the Baltimore & Ohio EM-1 had the longest combustion chamber (I could be wrong), although I don’t know its precise length. Does anyone know what The B&O EM-1 maximum outer boiler diameter and tube length were?
That would be correct. You could have a Challenger with similar wheel arrangement, but that is comparatively unlikely; we have to look for a moment at some constructional differences to appreciate why.
In large firebox design you want to increase the length of the radiant section, which is one of the ‘secrets’ of the deep firebox with arch (and arch circulators). Remember this is luminous carbon flame, not just hot transparent gas, so emitted black body radiation can be absorbed by the (black at saturation temp for boiler pressure) inner box and chamber liner at the 4th power of temperature. This implies that average TOF from above the grate through to the rear tubesheet gives complete combustion right down to a couple inches into the tubes… at which point the gas will be at less than atmospheric pressure.
Note that the ‘six wheel truck’ does not necessarily give you ‘higher horsepower’. There is a fairly hard limit of under 8000hp on a practical single-unit locomotive, and it is set by water rate and useful range; you may note that both the PRR Q2 boiler and its development on the V1 turbine were quite happy with 4-wheel support trucks on a railroad with lower permissible axle load than C&O, both these engines producing more horsepower at peak than an Allegheny, so we look a bit ‘elsewhere’ to account for the three axles. In my opinion they bear the extra weight of the syphons, etc., in the enlarged grate area, rather than permit a “larger” grate that makes more steam from water you can’t economically carry. (The extra axle messes with the ashpan
[quote user=“Flintlock76”]
There was a Texas oil millionaire named Connie Edwards who had a hanger full of Spanish-built Messerschmitts, if you’ve seen the movie “Battle of Britain” you’ve seen the planes.
I found a video of Connie and his Spanish Messerschmitts. Very interesting if you’re into Warbirds, if not, don’t bother.
So this 4-8-8-4+4-8-8-4 Garratt Big Boy that was proposed, in simple articulated form in order to supply eight 24” x 32” big boy cylinders, you’re going to be needing a boiler with an evaporative capacity of around 200,000 lbs/hr of steam. If we take Ralph Johnson’s suggested value of 80lbs of steam evaporated per sq ft of direct heating surface, and apply a corrected indirect heating surface factor accounting for tube length (in this case 22 ft), you end up with the Union Pacific 4884-1 Big Boy boiler having an evaporative capacity of ~ 101,000 lbs/hr. Also this 4-8-8-4+4-8-8-4 big boy Garratt would then require a water capacity of perhaps 45,000 - 50,000 gallons, unless the engine is intended to stop for water more frequently.
But you didn’t start with that boiler, or any other similar pathetic compromise. Even a relatively unmodified Q2 boiler would get well north of that mass flow… even assuming that ‘stock’ Big Boy cylinder dimensions were conserved with the higher available pressure, which is not the likeliest design decision. (Before you ask, yes, people in North America knew how to make Beyer-Garratt steampipe joints tight at 300psi on typical track.)
In practice, you would use what I said: a boiler with lagged shell right out to the applicable clearance, set low enough in the cradle to permit proper steam separation with the whole of the convection boiler full of tubes/flies like a HRSG. We could niggle about what proportion of the space under the cradle is devoted to water tankage (a la Union Garratt) vs. economizer and air preheaters vs. practical ‘ashaveying’ – the point being that you aren’t limited to the silly dimensional and design restrictions of a high-firebox engine essentially using partial pulverized-fuel firing of low average heat content.
Read my points above concerning water rate and range, then look at why the PRR V1 turbine was cancelled (and not revived after the Bowes drive made it practical to operate). The situation becomes worse rather than better if you try to ameliorate this with some form of condensing: you’re basically having to dissipate some large proportion of the heat from that fire on your grates at similar rate to its generation. Even net of all (considerable!) losses this is a losing exercise. The ‘best’ solution is to use greywater
Incidentally you should at least consider better circulation systems than Johnson was assuming --ideally combined with more positive steam separation. The Cunningham system alone is supposed to be good for ~12% greater effective mass flow through reduction of critical DNB even in an otherwise-unmodified Stephenson firebox; the more logical solution has (for a long time) been to adapt the Lamont forced-circulation water construction (where the water is circulated through the tubes at something like 6x the demanded mass flow of steam, for a nearly-trivial pumping power since there is little pressure-head difference from hot well through to steam-separator input, perhaps on the order of 10hp for one this size). The entire circulating mass goes through baffled centrifugal separation (the power for which is provided ‘free’ as part of the circulation pump operation) – steam goes up, water goes down, very little ‘priming’ action is in a vector that would produce, let alone facilitate, carryover. It is much easier to size and package a steam generator like this on a cradle essentially offering the clearances of a depressed-center flatcar than to try it atop a fixed or hinged set of equalized drivers…
The 1925 Super-Garratt Patent 230,888 design for standard gauge gives a taste of what might have been had a Garratt design been able to take advantage of the more generous American loading gauge clearences and axle loads. I say taste because even this design is certainly not stretching the limits of what could be done with a Garratt on US railroads. Nevertheless, it’s an impressive engine.
It’s a 2-6-6-2+2-6-6-2 with 160 sq ft grate, 585 sq ft firebox heating surface, 7482 q ft of combined evaporative heating surface and 1818 sq ft of superheating surface. Boiler pressure is somewhat low at ~177 psi. It’s eight 19" x 26" cylinders look very manageble relative to the mass flow of the boiler.
Another Garratt I would have like to have seen would have been some the of express passanger 4-6-2+2-6-4 proposals in Britain. One was a six cylinder compound with 81 inch drivers. In Britain the Garratt locomotives that did exist on the standard gauge system such as the LNER U1 2-8-0+0-8-2 and LMS 2-6-0+0-6-2 certainly had among the largest boilers on the network, having boiler dimensions that would be difficult to achieve with any conventional stephensonian design on the British loading gauge.
