Biggest U.S. built diesel?

[Anonymous]

Good Evening American Railfans, (although I believe that it is still afternoon where you are).

I am a British railway enthusiast, but one with an interest in the railways of Continental Europe as well. I frequently look at, and occasionally contribute to, a German forum similar to this one.

Today, one of the German readers posed the question "which is the largest U.S. built diesel locomotive ever built, and does anyone make a model of it?"

I do not know the answer to this question, but have no doubt that someone 'over there' does!

I look forward to your responses, which I shall pass on to the German gentleman who posed the question.

Ron Fisher.

[Anonymous]

WIthout being american I'll answer :)

The biggest diesel ever built in terms of horsepower (6600 hp), weight (247 tons) and length (98 feet) was DDA40X Centennial. The biggest in terms of pulling power is SD90MAC/AC6000 - both around 890 kN (200000 lb) of starting tractive effort (DDA40X was around 600 kN - 135000 lb)

[gabe]

Is this counting diesle turbines?

[Anonymous]

I would have to agree on the EMD DD40AX for being the largest single unit locomotive but what about F-units? Some railroads considered an A-B-B-A lashup one locomotive. Such a lashup would be about 215' long and would weigh roughly 470 tons (940,000 lbs.)

[Sterling1]

I believe there were Bunker C fuel oil gas turbines, bulit by General Electric in the 1950s and used up to around 1969 when they were replaced by DDA40X Centennials. These gas turbines were rated between 4500, 8500 and 10000 horsepower.

[oskar]

well,it's the DD40AX there is only one left. I was talking to somebody in Folkston last monday and he said that the DD40AX got hit by a garbage truck so it is in the shops but I think that was a SD70 that got hit

any more questions





kevin

[feltonhill]

This is probably cheating, but the Pennsylvania Railroad had permanently coupled (drawbar, not couplers), 2-unit sets of Baldwin "Centipedes." They were considered one "locomotive". They were about 92' long per unit, roughly 185' or so for the pair, and were 2-D+D-2 each. They had four 1500 HP engines for a total as-built of 6000 hp. They were later derated to 5000 HP and consigned to helper service. Built around 1947, retired about 1962-1963. Models are available in both HO and O gage. Now how about a pair of these beasts in 1/32 G-scale.....

[Overmod]

IIRC KCS had 6000 or 8000hp "locomotives" that were Erie-built sets.

Many early railroads tried this approach (using letters to denote the units in a single 'locomotive', e.g. Santa Fe practice). It wasn't long before motive power people saw the relative pointlessness of leaving some units of a 'locomotive' idle while one was being repaired -- or of letting the 'rest' of the locomotive roam far from the shop by the time the one was fixed. So much easier just to take building blocks and make a consist...

Baldwin had a single-unit 6000hp prototype in the late Forties, slated to use modular V-8 engine-generator sets in racks, over an undercarriage similar to that used on the Centipedes. Rather interesting alternative to a 4-unit F3 set... although I can't conceive of it working right without much more sophisticated wheelslip control than was available then...

[M636C]

I wonder if the "6000", had it ever got all eight engines, would have been heavier than a DDA40X? Those frame castings wouldn't be light! The frame was used on one of Seaboard's Centipedes when even Baldwin realised that nobody wanted it. It wasn't as long as a "Centennial", of course, which is a major criterion of "Biggest".

Peter

[Overmod]

I'm almost certain you'd be right. Centennials only had eight axles, Centipedes 12, with substantially greater frame strength as well as weight. I've been trying for many years to find out exactly what the weight of one of the engine modules was -- I honestly can't say whether four gensets equals one big 645 with traction generator...

Of course, for many services you still need more than eight traction motors -- what I would expect from the 'modular' would be two semipermanently-coupled units a la Pennsylvania, with the desired number of gensets in each carbody. Note that this would still be fewer traction motors than 3 C-C locomotives, albeit with better cooling arrangements possible. Presumably it would be practical to start up and shut down the relatively small engines as needed to 'trim' the amount of available power for fuel conservation -- I proposed something similar (with modular gas-turbine generators) in the early '70s.

By the way -- there is a picture in Clessie Cummins' book of a "Zephyr" carbody with multiple gensets installed. I have never seen an organized discussion of this, or how it worked in practice. There's a certain bean-counting appeal to using only the amount of engine needed hour by hour to run the train effectively...

[jchnhtfd]

The GE gas turbines used on the UP were just that -- not diesels. The DDA40X is it, and yes there are a number of models of it. They straighten model track almost as well as the real one straightens real track.

The Centipede was a fascinating idea... always an interesting engineering choice: do you use a number of smaller modular units to do a certain job, or one (or a few -- e.g. the EMD E units with two) bigger ones. As overmod says, there is a certain bean-counting appeal to the modular idea, but there were some rather sticky control problems... which are all solvable, but...

[Anonymous]

The first three DDA40X were manufactured at 7000 hp and later detuned to 6600 hp
by changing injectors.

More info and pictures may be found at

http://www.steamlocomotive.com/centennials/

[Anonymous]

Thank you, gentlemen, for the information. These DDA40Xs sound pretty impressive beasties. I shall pass this on in my best German to the enquirer as this seems to answer his query. I am assuming that he means biggest in terms of a single unit, rather than two/three units permanently or semi-permanently joined together.

Can anyone say which manufactures offer, or have offered, models of these things?

Ron Fisher.

[railman]

Athearn (did) offer a model of the DD40/35?- a close cousin but it would take some work to get it to detailed standards.

[rrnut282]

I think it was also available in brass, but had a price tag proportional to the prototype (it made my heart skip a beat, but I didn't have a job at the time I asked). You have to search e-bay or estate sales to find one now. The Athern model is a DD40. The major difference would be that the DD40, if it was every built, would have had a standard EMD cab and the DD40AX had a verson of the wide cab. These are for HO scale, I can't tell you about other scales.

[Anonymous]

Not to be stupid or nothing but what year are we talking about!

[Anonymous]

Bachmann Spectrum has made a DD40AX in HO and N scale.

[espeefoamer]

There are 11 DD40AXs in museums,10 in the USA and one in Mexico.The UP keeps one in thier historic collection,and uses it occasionally when they are short of power.I am pretty sure the Bachmann DD40AX is out of production.

[Overmod]

DDA40 Centennial: Built 1969, many ran until 1986, quite a few preserved.

DD35 (5000hp two-engine precursor, cabless only) UP 1963, SP 1964

Centipede: starting 1945

[M636C]

Overmod,

Could you expand on your earlier Zephyr comment?

Apart from the "Silver Charger" with the single 12-567, the previous units were twin engined, 1800 HP, mechanically basically similar to ATSF 1A and 1B, and effectively E units, without idler axles (since thy didn't need steam generators). These were each coupled to a B unit with a 16-201A of 1200HP.

I'm not sure what multiple generators you are talking about, unless you are including the hotel power sets that were fitted in some Zephyrs?

Peter

[Anonymous]

QUOTE: Originally posted by Overmod

DD35 (5000hp two-engine precursor, cabless only) UP 1963, SP 1964

Cabless only? In 1965, there were 15 DD35A's built. A total of 30 DD35B's were built from 1963-1964.

[Overmod]

M636C -- you have neatly put your finger on something I dearly want somebody to answer. I keep hinting, but no one will 'bite'...

The reference is in Clessie Cummins' book about his life with diesels -- there's a somewhat grainy picture of the inside of the forward end of a motor train. Caption says something either about Zephyr or Burlington (don't remember, but can look it up next time I'm in the U of M library). Area normally occupied by a longitudinal prime mover/generator is taken up with a fair number of smaller Cummins diesels -- far more than would be needed for hotel power in the '30s. Cummins himself talks quite a bit about his efforts to interest railroads in light diesel -- he notes, for example, that PRR would have gone into dieselization in a big way in the late '20s, but a key motive-power figure supporting the idea died, and his replacement discarded diesels as toys. I found nothing about this CB&Q locomotive... perhaps this indicates the idea was less than a howling success...

[Overmod]

BTW, Mike is quite right about DD35As. (I particularly like the canted radiators on these)

In a sense, the DD35 ought to be considered along with a pair of 'sandwiching' units as a single locomotive, as the idea was always to run them that way. Supposedly EMD intended to sell DD35s with a GP35 on either end -- that would make the resulting "locomotive" 10,000hp. With a cab on each end...

[Overmod]

But were they actually sold that way to any road -- in 'sets' of three?

[Overmod]

See what I learn from these posts?

OK, if the demonstrator counts as a 'locomotive' -- it's 15,000hp (which if I recall correctly isn't far off some of the substantial MUed consists UP was running at about that time). Be interesting to know how many consists included two of the DDs together with other units...

[M636C]

One of my great missed opportunities was DD35/35A/DA40X units on UP. I saw one train in 1977, and my recollection was that it had an SD40-2 leading a DD35A and a DD35 on Cajon Pass. I really wanted a shot of a DD35A leading!

The world didn't hate me that much, the next day we went to Colton and got an SP(!) U50+DD35 consist (that's all, two red and grey eight axle 5000HP units). I think the camera was shaking a little as the train rolled under a road overpass!

But I have a thought about the Burlington -didn't they test a Budd rubber tyred (Michelin) railcar a bit before the Zephyr. It might have had multiple small engines - certainly some of the French "Michelines" had multiple Bugatti v-12s, I think.

And Rock Island rebuilt some strange early motor trains - I'll see if I have any references.

There was a "History of Cummins" that I started reading when the sales rep was late for a meeting at their offices. I asked if I could get a copy, but I didn't get one.

Peter

[M636C]

Overmod,

I spent some time fruitlessly checking anything that might have listed a Cummins re-engined EMC or similar gas -electric motor car. In Australia, the Victorian Railways replaced the big Winton with a Detroit "Twin 71" (a pair of 6/71s geared together driving the original GE generator) in the early 1950s.

I thought I'd check a reprint of a Burlington passenger car diagram book, but for some reason, the only motive power included was 9900 herself.

It did show the leading cars of the 9904 and 9905 sets, with their distinctive dome matching the taller locomotive profile. These cars "Venus" (960) and "Apollo" (961) show three transverse diesel generator sets (engine unspecified) driving GE 50kW generators.

It also showed the equivalent cars of the 9906 and 9907 sets, "Silver Herald" 321 and "Silver Courier" 322, (Baggage , Mail and Auxiliary Power cars). These had four transverse generator sets, in this case specifying again 50 kW GE generators driven by "Cummins Motors".

I have no doubt that these cars are those illustrated in the Cummins book. I would have expected Winton engines, but perhaps appropriate engines were not available in late 1936.

The big Joint UP trains, the "Cities of SF/LA", the 1/2/3 and 4/5/6 trains, had big auxiliary cars with a strange mixture of large and small diesels, at least some being Winton.

Anyway, that's my guess about the Cummins engines, and I have drawings to back me up!

Peter

[railman]

QUOTE: Originally posted by espeefoamer

There are 11 DD40AXs in museums,10 in the USA and one in Mexico.The UP keeps one in thier historic collection,and uses it occasionally when they are short of power.I am pretty sure the Bachmann DD40AX is out of production.

In excursion service? Or do they use it when they get short of motive power for "real trains"?

[railman]

QUOTE: Originally posted by M.W. Hemphill

Those are all real trains. Seriously!

Generally the 6936 (the DDA40X UP has in its historic locomotive collection) is used for engineering department inspection trains, and occasionally on excursions. They have occasionally used it in revenue freight service in recent years.

I don't usually say this about the UP, but that's JUST PLAIN COOL!!!!!

BTW, all trains are real trains. You know what I mean.

Next, let's see if they get goofy and plug that big Challenger in front of a double stack hot freight on some cold dark night...

[M636C]

This is getting a bit off topic, but my comment about Joint Train power cars was wrong. After I posted, I pulled out Kratville's "Streamliners" and found that the LA/SF 1,2,3 trains had only twin Winton 8-201As side by side in the centre of the Auxiliary/Baggage car (and of course had porthole windows to pass out the pistons and rods, like E units). But between 1934 and 1937, the size of train had grown so that the "City of LA" had twice the power for hotel services that the "Pioneer Zephyr" had for propulsion.

The trains with messy auxiliary cars were the earlier straight sided cars on the City of Denver and City of Portland, the trains that used the three unit turret cab diesels. These were built (a bit hopefully) with a single Winton 8-201A, but later got three Detroit 6-71s (at 50kW each) and even later this was reduced to two 6-71s.

But to return to the "big" trains. The generators were removed from the 1,2,3 trains. What replaced them? Did the cars get batteries and axle drive generators? Were the big auxiliary sets to provide electric heating, replaced by steam as the "streamliners" merged with the older fleet? I think the E-2s always had steam generators, but perhaps they weren't used initially on the 1,2,3 trains.

(At least we are near topic, discussing the UP)

Peter