Paul,
right, I forget the T1. The other one I knew was the Western Maryland Potomac. I meant for freight service in first order. Anyway, they were all dual-purpose engines, even the Niagara pulled freight in their last years.
Again, stupidy by me, steamlocomotive.com has a fine complete list, do not need another list here.
For speeds: The NW J reached 110Mph (with 70" drivers / Sad, never have seen a Brass model of the J unskirted, they looked awsome) under tests with a 11 car consist, I think.
I am not aware of recorded speeds of other engines.
Generally, the 4-8-4s pulled trains of 1000tons or so, more than the fast Hiawathas. The later ones were also pulled by F7 Hudsons (Alco) with 84"wheels. See GP-40-2 comment, too: 25-26 cars at 80Mph or more? This must be 2000 tons plus somewhat, really impressive.
Lars
Freight 4-8-4's:
Western Maryland J-1s (1400's), Baldwin 1947
Rock Island R-67s
Milw S2's and possibly S3's (e.g.261)
Lehigh Valley T classes
Wabash O1
Frisco 4500's
C&NW H
MP 2100's, 2200's
RDG T1
Soo O20
TP&W 80-85
DL&W Q classes, except for Q4
N&W 610 reached 109 mph with 13 cars, 110 mph with 15 cars and 111 mph with 11 cars on PRR, Dec 7 & 8 1944. Locomotive was being tested for comparison with the two T1 prototypes. Speeds and consists documented by test report data and both N&W and PRR road foremen reports surviving at Hagley Library and N&WHS archives. Full story in N&WHS mag, The Arrow, Vol.24, #2 and PRRT&HS mag The Keystone Vol 41, #4. Not too bad for 70" drivers.
Not 'alf shabby 't'all! It makes me wonder what upgrades to the Jubilee class could have accomplished. A Canadian Pacific Jubilee holds the Canadian steam speed record.
At the same time, as a bit of a diversion from the topic (but discussed already), I can't help but wonder what the T1 Duplex would have been able to do if it had been kept and modified/tweaked for another 6-10 years.
Or, the Northern class, for that matter.
-Crandell
Lars LocoPaul, right, I forget the T1. The other one I knew was the Western Maryland Potomac. I meant for freight service in first order. Anyway, they were all dual-purpose engines, even the Niagara pulled freight in their last years. Again, stupidy by me, steamlocomotive.com has a fine complete list, do not need another list here. For speeds: The NW J reached 110Mph (with 70" drivers / Sad, never have seen a Brass model of the J unskirted, they looked awsome) under tests with a 11 car consist, I think. I am not aware of recorded speeds of other engines. Generally, the 4-8-4s pulled trains of 1000tons or so, more than the fast Hiawathas. The later ones were also pulled by F7 Hudsons (Alco) with 84"wheels. See GP-40-2 comment, too: 25-26 cars at 80Mph or more? This must be 2000 tons plus somewhat, really impressive. Lars
Reminds me of another what might have been;
"Unfortunately, the Chessie was put off by this shift in ACE's corporate design philosophy, and a sharp drop in the price of diesel fuel greatly reduced their interest in converting to coal fuel, reducing their interest in financing the ACE prototype. While they had already contributed significant funding, (all of which was spent to pay the bills generated from the 614T test runs), Chessie withdrew their support for the project. There were high hopes that the U.S. government, who had set aside millions for projects to produce liquid fuels from coal, would back the ACE project. One of the chief aims of the January 1985 tests was to gain publicity for the project. Unfortunately no federal funds were ever released to ACE."
_Ultimate Steam Page
Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has.
Paul_D_North_JrI agree with you on classifying the T-1 as not a 4-8-4, but just wanted to see what others thought on that as well. My recollection is that the T-1 was designed not so much to outperform the diesel, but to provide a modern steam locomotive - the K4 design dated to what, 1910 or so ? - and even at that wasn't all that modern, hence it was pretty much obsolete. Listed below are the several articles on the T-1's from Trains. I recall that Vern Smith's August 1967 article felt that they were under-rated - I beleive he credited them with routinely doing the 120 to 125 MPH runs, and concluding one section by writing something like, "What can you say about an engine where the crews complained that they were dirty [from coal dust from the tender swirling into the cab] at 125 MPH ?" Evidently, that was a legitimate problem, too. Riding the Pennsy T1 Trains, July 1943 page 32 Pittsburgh to Harrisburg ( 4-4-4-4, "DAVIS, RUSS", PRR, STEAM, T1, ENGINE, LOCOMOTIVE, TRN )
I agree with you on classifying the T-1 as not a 4-8-4, but just wanted to see what others thought on that as well. My recollection is that the T-1 was designed not so much to outperform the diesel, but to provide a modern steam locomotive - the K4 design dated to what, 1910 or so ? - and even at that wasn't all that modern, hence it was pretty much obsolete. Listed below are the several articles on the T-1's from Trains. I recall that Vern Smith's August 1967 article felt that they were under-rated - I beleive he credited them with routinely doing the 120 to 125 MPH runs, and concluding one section by writing something like, "What can you say about an engine where the crews complained that they were dirty [from coal dust from the tender swirling into the cab] at 125 MPH ?" Evidently, that was a legitimate problem, too.
My first thought on seeing the July 1943 date was who would have a copy of that issue lying around... then realized I had my father-in-law's first three volumes of Trains (bound) sitting right next to me...
Looked up the article and it was pretty light on details, with the emphasis on relating what it was like riding in the cab - it was pretty much the most futuristic looking steam locomotive in the US at the time. The top speed on that run was 75 MPH. A couple of design specs were mentioned, the first being able to haul 880 tons of train at 100 MPH, the second in being able to run from Harrisburg to Chicago with one fueling stop.
At the time the article was written, only two T-1's were in existence, 6110 and 6111. 6111 was equipped with a booster, but not 6110.
erikem - That's funny ! I almost deleted the references to the 2 earliest issues that I don't have, but then I thought, "Well, someone might have those issues, or want to get them, so I'll leave those citations in anyway for completeness." Glad I did ! Thanks for filling us in with what it said.
Lars - To follow-up on our posts of yesterday, here's a summary of what Brian Reed wrote in the Locomotives in Profile article on "The American 4-8-4" (Volume Two, published by Doubleday & Company, Inc., New York, 1972, and Profile Publications Limited, Windsor, Berkshire, England, 1972, pp. 169 - 192):
On freight service: Not much - mainly: "A theoretical defect was the small proportion - usually 58 to 62 % - of the adhesion weight to the total loco weight. Thus the 4-8-4 was not effective for drag freight; . . . the extra power at speed permitted substantial accelerations of passenger and freight trains of any weight the locomotive could start; and this outweighed any theoretical disadvantage." [pg. 170, right column, middle] Other than that, he only states generally that they were used in dual service or for fast heavy freight service.
On 100+ MPH speeds: Mainly that: "After the A.A.R. tests of 1938 already mentioned*, the Union Pacific made modifications for its next batch of 4-8-4s, nos. 820-34, which were intended specifically to run up to 100 m.p.h. whenever needed and to meet a design specification of 110 m.p.h. top." [pg. 183, right col.]
* - The "A.A.R. investigations of 1938 to determine what output and layout were needed to accelerate 1000 tons of passenger stock to 100 m.p.h. and keep it at that rate along the level. No locomotive of the handful tried could rise to that performance. Nearest was the U.P. 4-8-4 no. 815, which with a 16-car consist of 1005 tons reached 89 m.p.h. up 0.15% (1 in 660), and a peak of 102.4 m.p.h. down 0.2% (1 in 500). This was a 77-in. wheel engine with 300 lb. boiler pressure that could develop over 4000 d.b.h.p. . . . the A.A.R. trials themselves set the pace for new fast passenger developments which, apart from the Pennsy duplex classes, culminated in the 1940s in such machines as U.P. nos. 820-844, the S.P. classes GS4 to GS6, and the N.Y.C. Niagaras - 4-8-4s that could get up to 6000 i.h.p." [pp. 173, lower right col. - 174, top left col.]
Other than this, he mentions only that one of the N&W J's had touched 110 MPH on a special test, and that "these passenger engines had a higher starting tractive effort than any other 4-8-4; and their peak drawbar output must have been close to that of the N.Y.C. Niagaras". [pp. 188, bottom right col. - 189, top left col.],
He also mentions that one "subsidiary" reason for the duplexes was a concern that a 4-8-4 with 27-in. diam. cylinders could not exhaust steam fast enough through 12-in. piston valves, but he points out that such engines ran up to 85 - 90 m.p.h. with 600 to 1000 ton trains - others had 14-in. valves, and 1 batch on the Santa Fe even had 15-in. valves. [pg. 173, middle left col.]
I also note that the U.P. 800s had Walschaerts valve motions, while the NYC Niagaras used Baker. ["TABLE III, - VALVE MOTIONS OF 4-8-4 LOCOMOTIVES", pg. 177, top]
On NYC Niagara's HP: - From "TABLE VIII - OUTPUTS OF N.Y.C. NIAGARA 4-8-4 LOCOS" [ pg. 191, top]:
Class & Road No. Wheel Dia. Pressure Max. i.h.p. Max d.b.h.p. Act. Start T.E.
S-1a 6000* 79 290 6800 @ 85* 5290 @ 62* ?
S-1b 6023 75 275 6600 @ 77 5100 @ 58 65,800
S-1b 6023 79 275 6610 @ 85 5050 @ 62 62,500
S-2a 5500 79 275 6625 @ 90 5000 @ 65 62,500
* - On Selkirk test plant [this one only].
Hope this is informative.
- Paul North.
hi, good choices but a little correction--two os southern pacific's 4-8-4's...GS5 CLASS..did have full rollerbearing axles--same as GS4 CLASS-- which did not have roller bearings
Hello all 4-8-4 enthusiasts!
Feltonhill:
Thank you for the list, looked at steamlocomotive.com with a glance, these are more classes than expected. ( twelve 4-8-4 for freight service? Must be the dirty dozen )
Wallyworld:
the ACE is a nightmare, neither fish nor flesh.
Paul:
Great references you list here.
the statement...
On freight service: Not much - mainly: "A theoretical defect was the small proportion - usually 58 to 62 % - of the adhesion weight to the total loco weight. Thus the 4-8-4 was not effective for drag freight; . . . the extra power at speed permitted substantial accelerations of passenger and freight trains of any weight the locomotive could start;
is really negliable in my point of view. Any x-8-x of same adhesive weight will pull same. Someone may think a 2-8-2 for example is better drag-suited, because its smaller (and more "effective"), therefore?But horsepower pulls the trains, and the 4-8-4 could carry bigger boilers. Anyway, never load a steamlocomotive of any type towards its lower boiler capabilities, as effectiness goes hell. For drag, use diesels or electrics ;-)
On 100+ MPH speeds:
maybe some 4-8-4 were handicapped by their gear or so. I think for most US railroads 100mph was good enough, as I wrote before, they pulled pretty heavy trains over long distances.Have a look at http://files.asme.org/ASMEORG/Communities/History/Landmarks/5609.pdf : there it is stated, that the N&W J drivers and rods were balanced up to 140mph, and for sure, the SP's UP's, C&O's, ATFS's or Niagaras ones were equally good. Just Imagine what a 4-8-4 could do with a light 5-7 car train and a big coffee pot next to the engineer.
Class & Road No. Wheel Dia. Pressure Max. i.h.p. Max d.b.h.p. Act. Start T.E.S-1a 6000* 79 290 6800 @ 85* 5290 @ 62* ?S-1b 6023 75 275 6600 @ 77 5100 @ 58 65,800S-1b 6023 79 275 6610 @ 85 5050 @ 62 62,500S-2a 5500 79 275 6625 @ 90 5000 @ 65 62,500
Fellows,I get suspicious, a test-plant result again in the first row, but could the Niagara really produce so much IHP? Just think about it, the Big Boy's cylinder horspower was 6680~40mph. Nevertheless, if the dbhp is correct, these engines (in addition the N&W J, have a look at my link above) produced same horsepower as a Class A or Big Boy at speeds ~60mph, to put some perspective here.
Kind regards
lars
Lars-
You were right to be a bit suspicious regarding the high IHP figure for the 290psi Niagara. However, it's probably close to a possible max figure at that pressure. I'll have to see if I have any confirmation of this, but I believe most of the 290 psi Niagara figures developed by NYC were calculated, not actual. Oh., BTW, NYC did not have a test plant like PRR did at Altoona. That statement is misleading. NYC frequently did stationary testing at Selkirk, which is a perfectly valid testing methodology, but it is not the same as the dynamometer test done by PRR. I'll try to track down how NYC came up with the 290 psi figures. The maximum IHP figure can be found in Paul Kiefer's book, A Practical Evaluation of Railroad Motive Power, pg13. According to a data table, the S1 at 290 psi developed 6900 IHP at 85 mph.
Be careful when using the ASME booklet. The 300 psi DBHP curve for the J is extremely suspect. It was calculated using an unknown method. This was discussed at some length in NRHS Bulletin Vol.57, #5, 1992, which contained an article on 611 by Arthur Bixby. There was also some commentary in Bulletins following the initial article. Because the shape of the curve is different with the only change being the increase in BP, I have serious doubts that it was anywhere near reasonable (as did others far more knowledgeable than I am, when the graph appeared). There was talk at the time that Bixby may have been misled by someone presenting himself as knowledgeable and arguing that the N&W DBHP curve for 300 psi calculated in 1945 was too conservative. IMO, the curve tests out to be similar to a Baldwin IHP curve (not DBHP), which bears no resemblance to actual IHP curves developed either on test stands like Altoona or over-the-road.
As I've written here before, analyzing and comparing steam locomotive performance is a very difficult process, if it's possible at all.
Feltonhill,
'tip my hat again about your superiour knowledge and helping us to put some data into right order.
feltonhill As I've written here before, analyzing and comparing steam locomotive performance is a very difficult process, if it's possible at all.
Yes, as before another member at a different thread pointed out preciesly "to sad, they did not do tests like "Road & Track" on steamlocomotives...
It is even more frustrating with books, many figures must be carefully examined and revised with other sources. Often numbers are out of whack (es. German books featuring US engines, aarghhh!); you think you are lucky to gain some drawbar tests, only to be got teached to forget all about this again... its a natural learning process in general.
Great, here are very well informed members on this forum, willing to grant some knowledge.
BTW: looked at J's technical drawing at the ASME booklet, dated 1982, the rated max. drawbar hp is 4400. Hmmm, maybe nobody told the J about that, itseld did not care about it and put additional 600hp?
Since you mention it......The 4400 horsepower figure for the N&W J was first used in a specification list dated March 11, 1941, seven months before the first J was completed Oct 20, 1941. It is a Rated Maximum Horsepower figure, and is apparently based on a maximum evaporative capacity (N&W's words) of 11,500 gallons/hr, or about 95,833 lbs/hr total evaporation, BP of 275 psi. I ran this through the Baldwin estimating method that was favored by N&W in that era, and came up with a calculated drawbar HP of 4410 at 35 mph, using an evaporation rate of 74.4 lbs water/SF of DHS/hr, producing a total figure including FWH of 95,833 lbs/hr. These figures are too close to be coincidental, so I believe I correctly used N&W's method of estimating. Moving ahead to 1982, I found NW Mechanical Dept Drawing for 611, no number but the date is 7-28-82, initialled by M.D.B. This drawing replicates exactly the Nominal Top Speed - 85 mph and Rated Maximum Horsepower - 4400 words and figures from the March 1941 specification sheet. This is virtually the same drawing as published in the ASME booklet.
Based on the above I have to assume that (1) 4400 is not an actual rating, and (2) it is based on a 275 psi J, not 300.
Just by way of a tickler, the maximum DBHP for a Class J is not 5,028 at 41 mph. N&W never said it was. The often cited DBHP curve was calculated using the Baldwin method. It was neither actual nor maximum at 300 psi. N&W so stated and cited its estimating method.
Hope this helps
For passenger service, I'd like to put in a vote for the Rio Grande's 1800-series 4-8-4's. They could pull an 18-car train up a 1.4% grade at 40mph. They were the first Rio Grande steamers with a one-piece cast steel frame, and had roller bearings on all engine and tender wheels. And they were mighty handsome devils, too, perhaps the best-looking of all 4-8-4's.
feltonhill Since you mention it......The 4400 horsepower figure for the N&W J was first used in a specification list dated March 11, 1941, seven months before the first J was completed Oct 20, 1941. It is a Rated Maximum Horsepower figure, and is apparently based on a maximum evaporative capacity (N&W's words) of 11,500 gallons/hr, or about 95,833 lbs/hr total evaporation, BP of 275 psi. I ran this through the Baldwin estimating method that was favored by N&W in that era, and came up with a calculated drawbar HP of 4410 at 35 mph, using an evaporation rate of 74.4 lbs water/SF of DHS/hr, producing a total figure including FWH of 95,833 lbs/hr. These figures are too close to be coincidental, so I believe I correctly used N&W's method of estimating. Moving ahead to 1982, I found NW Mechanical Dept Drawing for 611, no number but the date is 7-28-82, initialled by M.D.B. This drawing replicates exactly the Nominal Top Speed - 85 mph and Rated Maximum Horsepower - 4400 words and figures from the March 1941 specification sheet. This is virtually the same drawing as published in the ASME booklet. Based on the above I have to assume that (1) 4400 is not an actual rating, and (2) it is based on a 275 psi J, not 300. Just by way of a tickler, the maximum DBHP for a Class J is not 5,028 at 41 mph. N&W never said it was. The often cited DBHP curve was calculated using the Baldwin method. It was neither actual nor maximum at 300 psi. N&W so stated and cited its estimating method. Hope this helps
feltonhill,
thank you for your correction and clearing this,
I am new to this forum, and just came across this thread from years ago about which was the "best" 4-8-4. So I am not sure anyone initially involved is even still participating in tihs forum. However, after reading the comments I did have one thought I wanted to offer. While the participants made a number of very valid points to defend their choice, I expect most of them were - like me - more involved with railroads as a hobby rather than a vocation. Moreover, no one seems to have much actual experience with steam locomotives - not surprising given how much time has passed since they were actually used in revenue service. Therefore I felt it worth mentioning that a well known writer who actually had first hand experience riding many railroads' steam locomotives - and could therefore knowledgeably draw comparisons - was very clear in several of his books about which 4-8-4 was the best one in the nation. The writer was S. Kip Farrington, Jr., and his clear choice was the Santa Fe 3776 class engines.
Hi, Chuck, and welcome. I am still here, some have moved on one way or another.
As I said in my original reply in 2009, the topic has to be 'managed' with a strict adherence to criteria or it becomes a fan-boy discussion and little else. What criteria did Farrington feel were the most salient ones, why, and what were his various conclusions based on something more than his senses when in the cab of a wide variety of 4-8-4 steamers? Did he account for the confounds of driver skills, terrain, trailing tonnages, state of the tracks, proper valve adjustments, the lengths of runs between stops, whether the engine had roller bearings throughout, whether engines had been very recently shopped or were due to be shopped, and so on. Two engines of the same type operating with the same tonnages on separate days, but with different hogheads or firemen, would very likely offer different experiences and impressions to observers who managed cab rides both days. So, I wonder what published and verifiable data Farrington used to draw his conclusions, and if they would be widely supported by other experts in the industry.
As Feltonhill said later in the thread, many is the quicksand hole to be found in attempting to calculate the performance impetus in steam locomotives.
aboard!
Trains, trains, wonderful trains. The more you get, the more you toot!
Regarding Farrington's choice, I see no reason to question his choice of the last of the pre-WWII Ripley-designed 4-8-4's. The wartime engines had to make do without certain lightweight steel products that the last prewar engines had. My personal choice in 4-8-4's had always been the Norfolk and Western J, but this is a persoal choice, and would not question anyone choosing the Ripley AT&SF, the Central's Niagras, the SP's Daylights, the second group of Lackawanna's Pocanos, the C&O Greenbiars, CN-GTW, etc. All great locomotives, but all subject to who is running them, who is firing, what the trailing load is on a particular day, coal quality, even weather. An should be throw in the PRR T1 as well?
The 2900's have to be right up there from the Santa Fe. They were designed to run 90+ MPH with a 20 car passenger train and did haul those during the war. They also grabbed freight trains and hauled them all over the system. They got run hard 2926 in her 13 years of active service reached 1.5 million miles. They were underrated on TE also Santa Fe rated them at 66K when they actually had well over 75K lbs of power. The engineers and roadmasters knew it so they used the power in the hills.
Top 5:
C&NW H-1
CMStP&P S-3
CB&Q O5-B
UP FEF-3
CRI&P R-67
If I remember correctly, the one thing that stuck out in my mind reading Farrington's book was that he wasn't happy that he had to stand up while riding on the N&W J. Poor guy! I wonder how much that affected his rating?
.
It pays to remember that Farrington was something of an amateur enthusiast, more a duck hunter than a technologist. I remain unsure whether his coverage of the WM M-1 (in 'Riding the Locomotive Cabs') actually represents a superior design of late 4-8-4 otherwise rather pathetically underdocumented or just the presence at hand of good comparative data for the 4-8-4 and 4-6-6-4.
All this discussion and no mention of the seminal 242 A1.
And what's wrong with the Q4s?
Farrington may not have been an engineer, but I have to hand it to him for getting his hands on real engineering test data from the Santa Fe and then publishing it. If most decent-size railroads possessed test data on their steam locomotives at one time, very little has found its way into the hands of latter day students of steam locomotion.
Here is my top 5:
N&W J (Huge boiler, clever and unorthodox approach to running gear design)
ATSF 3765 class (Perhaps the only other 4-8-4 that could match the N&W J's physical specifications and peak output)
NYC S1a (The 4-8-4 optimized for very constrained Northeast loading gauge and NYC track pans)
UP FEF2 (Best of the UP 4-8-4's by virtue of its higher performing Type E superheater)
Milwaukee Road S2 (Seldom-mentioned type, fully qualified based on boiler & running gear specifications)
Seeing as there has been a resurgence, here is my top list:
SAR Class 25 (Condensor) such as 3511 “FREIDA”. What other Locomotive can attain speeds of 65-70 MPH whilst reusing the steam multiple times to avoid water stops? Oh, and did I mention it sounds like a jet engine rather than a steam engine. For a cape gauge engine, their 234 ton weight was massive. They ran at 225 PSI with a tracktive effort slightly over 45,000 (compare that to a D&RGW K-36 which can hit maybe 30 MPH with 36,000 pounds of tracktive effort).
SAR Class 26 RED DEVIL, literally a Class 25 (non condensing) rebuilt by Wardale in the style of the famous L.D. Porta, to be even more effective. It features a Gas Producer system, lempor exahust, Power reverse, and many other improvements and modifications, however the South African Steam age was already drawing to a close. Fast forward to 2018, and 3450 has just been returned to working order in signature red paint.
Of course one must then agnowledge at least 1 of the “traditional classics”,
SP GS-4 4-8-4, such as the famous No 4449, all that glory and power, and the other usual reasons.
Canadian Pacific K-1-a, everyone knows the CP H Class ”Royal Hudson’s”, but few are familiar with the big brother, the 4-8-4 variants, No 3100 and 3101, both of which spent time semi streamlined, and streamlined with smoke deflectors. They have 75” drivers and 60,798 pounds if tracktive effort, operating at 275 PSI (sure it isn’t 300, but this was 1928). They weighed in at more than 350 tons, sadly too much for some CP Rails, which limited their operational availability.
The great SAR 520 Class 4-8-4 (similar to a T1 nose wise), with the original being named SIR MALCOLM BARCLAY HARVEY, and being 1 of 2 preserved, and a noted preservation star,sadly curtailed by diminishing Broad gauge (5ft3) in South Australia. This class of loco even gained entry into the Thomas & Friends Series, as “SHANE”, despite still have the “SIR MALCOLM....” nameplates on the side. These locomotives could actually burn coal and oil. Their 66” drivers were fairly small compared to other American engines, but they were well suited for reasonable speed and climbing in the shallow gradients.
Essentially any 4-8-4 that isn’t N&W 611......
Why 3765 and not 3776 class? Please be specific because the small details here become important (to us motive-power nerds at least!)
I suspect a place should be provided for the Timken 'Four Aces' locomotive, probably far more important than the A-1 Berkshire in the evolution of modern steam -- and far, far better-looking, too. It's certainly the one most regrettably lost to preservation.
I have just joined this discussion as this has always been my favorite class of steam locomotive from when I was too young to understand different classes. First, I would like to say that unless we can line up these locomotives today and have some type of pull of or timed trials we can speculate all we want. That being said we do have a number of examples still left in operating order that some type of steam off could be arranged. More interesting to me is how only one Class I railroad has bothered to maintain its legacy as it was steam that powered the greatest challenge to our democracy has faced during WWII. Personally, I grew up along the North line of the C&NW railroad so I like the H-1s. Also I like FEF, but all the Northern class locomotives were the peak of locomotive engineering and it took a few decades for single unit diesel power to catch up. It was the costs a frequency of maintenance that killed steam power.
sgriggsUP FEF2 (Best of the UP 4-8-4's by virtue of its higher performing Type E superheater) Milwaukee Road S2 (Seldom-mentioned type, fully qualified based on boiler & running gear specifications)
Along the lines of Overmod's question:
Why UP FEF2 rather than FEF3?
Why MILW S2 instead of S3?
Overmod Why 3765 and not 3776 class? Please be specific because the small details here become important (to us motive-power nerds at least!)
Direct heating surface was significantly reduced on the 3776 class, compared to the 3765 class (ref http://steamlocomotive.com/locobase.php?country=USA&wheel=4-8-4&railroad=atsf). In terms of boiler evaporative capacity, direct heating surface (firebox walls and circulators) is approximately 6 times as effective as indirect heating surface (tubes and flues) on a lb evaporation per sq foot basis. The 3765 would be a more capable machine. I suspect the Santa Fe made the change because they felt the performance gain afforded by the additional siphons in the 3765 class did not justify the additional maintenance.
Scott Griggs
Louisville, KY
charlie hebdo sgriggs UP FEF2 (Best of the UP 4-8-4's by virtue of its higher performing Type E superheater) Milwaukee Road S2 (Seldom-mentioned type, fully qualified based on boiler & running gear specifications) Along the lines of Overmod's question: Why UP FEF2 rather than FEF3? Why MILW S2 instead of S3?
sgriggs UP FEF2 (Best of the UP 4-8-4's by virtue of its higher performing Type E superheater) Milwaukee Road S2 (Seldom-mentioned type, fully qualified based on boiler & running gear specifications)
UP FEF2 was built with Type E superheater, rather than Type A as built on FEF1 and FEF3. The Type E superheater was a more advanced design than the Type A, and nearly all late steam designs used the E rather than the A. Although I can't put my hands on it at the moment, I have seen references stating the type E produced higher superheat than type A. Higher superheat translates to more efficient steam use in the cylinders and more power.
If you compare the specifications of the Milwaukee S2 and S3, you will see that the S2 has a much larger boiler, a higher operating pressure (285psi vs 250psi), the same size cylinders, and the same size drivers. The S2's were thoroughly modern engines with cast steel locomotive beds and roller bearings.
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