There was a Union Pacific proposed 4-10-4 locomotive. Does anyone know where i could any info on this locomotive. Gary
Union Pacific rostered ten 4-10-2 locomotives that were three-cylindered machines developing 77,917 lbs of tractive effort on 63" drivers.
They were a precursor to the 4-12-2 Union Pacific type, which was developed as a fast freight locomotive with 67-inch drivers and three cylinders, with a long shallow firebox supported by the training truck and drivers, similar to the firebox configuaraton later seen on the 4-6-6-4 and 4-8-8-4 locomotives.
The 4-10-2 locomotives were later converted to two cylinders and 72,391 lbs of tractive effort.
That is the closest they ever got to a 4-10-4.
http://steamlocomotive.com/locobase.php?country=USA&wheel=4-10-2&railroad=up
https://www.deviantart.com/edjack14/art/Union-Pacific-5091-4-10-2-696668823
You’re going to have to give the reference on where this was proposed. I knew nothing about it, and have subsequently been able to find precisely nothing.
It would be logical for UP to look at something like a conjugated PRR Q2 for the parts of its heavy service to support the invasion of the Japanese home islands not suited to Challengers and 4000s. That would give you single-unit horsepower right up to water-rate range limitation, without the extreme firebox weight of, say, a double-Belpaire or other Lima-style fancy-circulation-at-substantial-mass construction. It might be highly interesting to see if modern balancing could be extended to an 8000hp 2-cylinder simple… as Bugs Bunny said, “naaaaah … could be”.
I would NOT sit around thinking of ways to optimize this to run on that silly subbituminous fuel burned in the articulateds. Although I suppose you could get it to work after a fashion…
The “proposal” was revealed in the August 1924 issue of Union Pacific Magazine. It was to be three-cylinder, with 73" drivers.
Ed
Strange that two years later and one driver pair larger they retained the 2-wheel trailing truck.
Was this a follow-on to the 1923 4-8-4 design we’ve discussed?
The locomotive was in Union Pacific magazine Aug 1924 and the drawing was in the Aug 1927 magazine. The locomotive was a 3 cylinder 73 inch drivers and 240 lbs boiler pressure. Gary
Can someone scan and post these two items? I don’t see any digitized version on the Web, the accessible copies mentioned by Don Strack are not near me, and I believe both issues are out of copyright…
1924 issue is out of copyright (more that 95 years), but the 1927 issue remains in copyright till 2022 or 2023.
I’d prefer an 80 year term…
On the design drawing I was looking at, they put 60,000 pounds on the trailing truck. Why would they need a two axle truck?
I made my post with information from “somewhere else”. Not from the UP magazine.
Ed
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That is the point. This is only a couple of years after ATSF put the experimental 4-wheel truck on a ‘heavy Mountain’ and perhaps is a response to that experiment. ALCO certainly thought the larger Nines did not need more than a two-wheel trailer, a year after the introduction of the Super-Power Berkshires.
I believe 73" was UP’s standard passenger driver size in 1924. And that size would be easily balanced on a three-cylinder engine…
Note that the 4-12-2 firebox was above some of the drivers. GN did this, too, on all their articulateds.
Some thought it necessary to have a tall capacious firebox, and so used a trailing truck that was substantially lower than the drivers. Somehow, the 2-6-6-6 comes to mind.
Both approaches seem to have worked pretty well for their respective railroads.
The big difference is that when you have a trailing truck, it takes weight off the drivers. And the bigger the trailing truck, the less weight on the drivers.
The one version quite possibly could generate more steam so the locomotive could go faster. The other pulled more.
I’m not sure of the timing, but I do wonder if the 4-10-4 wasn’t a move to make the 4-10-2 more of a passenger engine, which service it did perform. I note that the 4-10-2 did not have its firebox over any drivers. If you wanted more steam out of that engine so as to go faster, a 4-wheel trailer under a lengthed firebox is reasonable. So is enlarging the drivers.
And, of course, if you enlarge the drivers, you interfere more with the firebox, if it happens to extend over the drivers.
I believe the locomotive COULD have been successful.
Ed
It’s more complicated than that with big power. There is a minimum weight per axle that gives stable guiding – I think that was something around 30,000lb for big steam – but in most cases the lead and trailing wheels were given substantially more. Where the fun comes in at the ‘rear end’ is in weight distribution behind the engine equalization, the thing that was NOT perfected in the first iteration of the Delta truck circa 1918 or so, but so well in the later one.
Now guiding with a Delta is fairly simple: you arrange the pivot and length to the axle with the Bissel formula, run the equalizers either from a cross yoke or individually up the angle beams, and support the frame as far to the rear and outboard as you can with progressive loading cams or gear segments for centering. What this does not do, however, is support stuff the frame is bearing, notably the weight of the forward firebox structure. In some cases (the French 242 A1 is an example) two axles are used even though one could do the job with high axle load; the truck has a remarkably short wheelbase because it is ‘morally’ a two-wheel truck that has to use two axles. I have noted already that some of the articulated American Arch trailing trucks needed a laterally-floating second axle to allow the rear axle, too far back along a full drop firebox (in order to guide properly) to support the full of the weight.
An interesting question for discussion is whether a locomotive like a Fetter Challenger really needs a four-wheel instead of two-wheel truck at the rear. It clearly would if that firebox were a deep-drop design (as on any of the 2-10-4s built) but it could be argued that even a short-swing trailing truck like the one on a N&W Y cla
And then we have this trailing truck design:
None.
There were 25 of them in GN’s class N-3; they were built in 1941, and retired in '55-'57. I believe they were viewed as successful.
There was no weight on nor guidance from a trailing truck.
Ed
Actually they were extensive rebuilds of the 25 N-1 class 2-8-8-0 locomotives built by Baldwin in 1912. The N-1s were used extensively on the Iron Range in Northern MN hauling heavy iron ore trains to the ore docks at Superior, WI.
Supposedly after the rebuild they could do 60 mph with troop trains.
Great Northern for the most part operated with a philosophy of maximum weight on drivers, save for their two rather small 4-8-4 classes that were built primarily for passenger service, although they later aquitted themselves well on freight later in their careeers.
The 25 GN N-1’s were built by Baldwin in 1912. The N-1’s were rebuilt to N-2’s by GN between 1924 and 1926.
Regarding the N-3’s, “Steam Locomotives of the Great Northern Railway” says:
“This would be an entirely new locomotive, using an insignificant amount of material from the N-2.”
“Those that were used included the original journals and axles, driving wheel centers, sandboxes, turbo generators and while not stated, probably the whistle, bell and headlight.”
“The N-3 was considered an entirely new engine and received a new group number (Group 55) in the Unit Record of Property Changes.”
“It was to be able to be run at 50 mph, and it would have to negotiate a 16-degree curve.” (50" radius in HO)
All three classes used the same number series (2000-2024). So there was certainly no overlapping existence. Well, that’s not ENTIRELY true. Yes, there was always only a max of 25 locomotives. But. The first N-3 (2024) was delivered February 10, 1940. The LAST N-2 (2008) was brought in for “rebuild” October 11, 1941. So there was a time when there were both N-2’s and N-3’s. About a year and a half.
Another fun fact: The N-3’s produced 4200 horsepower. The NP Z-6 Challengers produced 4050. R-2 2-8-8-2 = 5193 HP.
Ed
Edward Sutorik
I have that book also. One thing that was not clear to me in that chapter was if they reused the frame or had new frames as part of the rebuild. I keep looking for brass 2-rail O scale models of both the N-3 and the R-2. Hard to find.
I do have a question on the proposed UP 4-10-4. Was the intent for it to be a fast freight hauler, or to be a passenger engine on mountainous terrain, taking over from the 7000-class 4-8-2 locomotives at Cheyenne or maybe Ogden and perhaps running on the LA&SL, where oil-fired Challengers held sway for a period of time on varnish?
“Commonwealth cast steel one-piece frames with integral cylinders were part of the design from the start.”
I had to go look up to see if the N-3 and R-2 were made in brass. I see they were. I wonder how many. Good luck on your search–either/both would be magnificent.
Ed
Hopefully, the article(s) in the magazine will reveal UP’s intent concerning usage.
Ed
While we’re waiting, though, I think 73" was a passenger driver diameter right through the late '20s. ATSF would famously use higher drivers on a ten-coupled without a four-wheel lead truck, but aside from that I think 69" to 70" was the maximum freight or dual-service diameter, including the NYC high-pressure 4-8-4 which should have been a high-speed design.
To me this is an attempt to take a consist from ‘the East’ of a certain length and work it over, say, at least some of the ensuing grades without helpers. This before the rediscovery first of simple articulateds and then the N&W/Alco independent discovery of how high-speed articulateds need no vertical hinging.
Theoretically even ignoring the smoother torque and reduced augment force from a balanced three-cylinder drive, the reduction in wheelrim mass alone would put the effective diameter speed of the engine above a conventional quartered engine with 80".