Although the solviet railway operated a 4-14-4 for a while, the 4-14-4 had
a 33 foot wheel base causing this engine to damage curves. Because of this
the locomotive was scrapped in less than half a decade after it was built.
I also know that used a 4-12-2 for a while, but there isn,t much history on it.
Luckily one is preserved in Pomona CA, along with a 4-8-8-4, a DD40X, & a
4-6-4.
Do Duplexes count?
Their success, or lack of it is probably arguable, but what about engines like the T1 4-4-4-4, or the Q2 4-4-6-4?
The UP 4-12-2’s make a strang argument though, and probably could be thought of as quite successful.
The UP’s 9000 class 4-12-2s were definitely successful. They replaced the railroad’s previous fleet of slow, compound Mallets and allowed a substantial increase in speed and tonnage.
They were not without their problems, but the UP was willing to live with the problems on account of their performance. They were hard on the track, of course, given the huge rigid wheelbase, and were restricted in where they could go. The worst problem, though, was the inside cylinder. The 4-12-2s were too big to be 2-cylinder locomotives, most likely, so they had a third cylinder driving a crank axle. Inside cylinders have always proven a pain in the rear, especially on freight locomotives that don’t get pampered. It’s harder to maintain them.
At least the 9000 class did not have an inside set of valve gear. They were all built with Gresley-Holcroft derived motion - this British invented gear used the motion of the two outside valve gears with a set of levers to derive a motion for the inside cylinder. The lever assembly sat in front of the valve chests under the smokebox, and can be seen if you look carefully.
The problem with the derived motion is that wear in the pivots is very amplified and they need constant maintenance to work well. For this reason, some but not all of the UP 9000 class were fitted with a third set of outside Walschaert gear.
The 9000s were largely replaced in their original roles by the Challengers, which gave the articulated locomotive extra rigidity in the vertical and twisting planes, making it more stable at speed.
The PRR’s Q2 4-4-6-4s were somewhat successful. The problem was that they were not enough better than the J1 2-10-4s to justify the extra complexity and maintenance requirements, and with the diesel coming, there was little incentive to try and fix any problems. They were exceedingly powerful and fast, though. One achieved the highest recorded steam locomotive horsepower ever, though few large articulateds were ever
Good choice, although I wouldnt say duplexes & jubilees exatly fit the category
“non articulated” .
Probably as a class the 4-8-4 Notherns were the most successful non-articulated locomotives. A case could be made for the 2-10-4 Selkirks as well although they were only used in the mountains between BC and Alberta where the Northerns were used everywhere in North America.
Duplexes weren’t articulated. The drivers formed one rigid wheelbase. Two sets of cylinders, yes. But no articulation.
Jubilees? That term means a 4-4-4. Hardly the largest.
passengerfan: you’re considering arrangements, not individual types. The 4-8-4 was overall quite a successful arrangement, though it was possibly less good for fast freight than some railroads seemed to think.
Odd that you consider all 4-8-4s of various designs yet you seem to restrict the 2-10-4 to CP’s Selkirks only. 2-10-4 was a very popular arrangement, though the passenger use of the CP’s units was unusual. Many 2-10-4s were highly successful.
Actually, although the Soviet AA class 4-14-4 was impractical, I understand that it remained intact until the late 1960s at least, outlasting most succesful US steam locomotives.
In general, the big 2-10-4s, like the ATSF 5011 class, were probably the most successful big rigid locomotives.
Peter
If one measures “success” in terms of “contribution to profit,” UP 4-12-2s were the worst locomotives ever made, according to the mechanical officers responsible for maintaining them. See Klein, Union Pacific, Vol. 2.
Railroads measure in profit.
OS
True that’s why the 4-6-6-4 replaced the 4-12-2.
I have to say the PRR J1 stood up to the wartime traffic very well.
Again, the C&O 2-10-4’s were better than the PRR’s because they had rear-truck boosters. But certainly, 2-10-4’s originally called Texas types because the first were on the Texas Pacific, were a widely applied long-wheel-base non-articulated, used by more than a few railroads, and used on mountains and on the level in a wide variety of freight service, and many lasted well into the diesel era, not being the first to be scrapped, like the duplexes.
Um, the PRR’s J1 locomotives DID have boosters. Look at any picture; they have the steam pipes leading back there.
The differences between C&O and PRR locomotives were, as far as I can remember, pilot, cab, tender, and fittings.
And that the C&O 2-10-4’s were the inspriation and guidiance for the PRR’s own J1. I believe that while both engines were very similar the more recent build of the J1 incorperated improvements in steam up to that time. The J1 fufilled the PRR’s need for the wartime traffic in a time when no new engines were allowed to be built. Existing designs had to be considered.
Therefore I nominate the J1 as the winner of the thread.
I see a certain bias here 
The thread calls for “world’s” most succesful, yet gets only locos from the USA ^^
The most succesful of non-articulated big steam locos would be Kriegslok BR 52 2-10-0 with just below 7000 examples built (not includng about 1000 derivatives). First built in 1942 by nazi germany these locos became widespread all over europe and after the war served anywhere from france to USSR with many having 50 years of service (the las were taken out of service about 1990).
If the sheer size is to be taken into account then bulgarian class 46 - 2-12-4 tank locomotives used for the steepest coal routes (sometimes triple headed). They also served several problem-free years.
And the aforementioned T&P 600’s lasted until they had enough diesels to replace them.
BTW, the class was designed to provide a replacement for the 2-10-2’s that could not negotiate Baird Hill (out by Abilene–a long hard pull–sort of the T&P version of Sherman) without either a helper or doubling. The 600’s were very successful at it and wound up all over the length of the line. There’s a post-WW2 AAR film that was reproduced on video a few years back showing a 600 rounding the curve off the Trinity River bridge onto Dallas UTCo trackage; look closely and you’ll see it’s the 610–the only one left, which pulled the AFT in TX, spent some time on the SOU, and now resides preserved on the Texas State RR in Palestine., where it can’t operate because it’s too heavy for the bridges.
the Chines QJ 2-10-2 are very successful too, and most likely to see out steam in the PRC. They still operate on the Ji-Tong-Railway
Don’t forget Brithish Rails last steam engines. You could use those decapods for fast passenger trains too.
Did any of these big locomotives use blind (flangeless) drivers?
Or some other technique (like slightly narrower gauge on the end wheelsets?)