Paul_D_North_Jr Hump duty, as I recall from that DPM essay - pushing cuts of 100 to 150 cars at a time up the lead to the yard hump, at a very slow and steady speed - where the more constant torque added by the 3rd cylinder would be a decided advantage over a 2-cylinder locomotive. I'll try to remember to take a look at that issue tonight and confirm or add to this as appropriate.
I'll try to remember to take a look at that issue tonight and confirm or add to this as appropriate.
Thought I'd posted this before, but apparently not:
The grandest 0-8-0 of all Trains, January 1968 page 18 Indiana Harbor Belt 3-cylinder 0-8-0 ( 0-8-0, FRONTISPIECE, IHB, "MORGAN, DAVID P.", STEAM, SWITCHER, ENGINE, LOCOMOTIVE, TRN )
Something-I-Never-Knew Before Dept. -
At that http://steamlocomotive.com website, there's a page devoted to 3-cylinder steam locomotives - http://www.steamlocomotive.com/3cylinder/
There, it notes that Baldwin No. 60000 - which has been on display in the 'Railroad Hall' at the Franklin Institute of Science in Philadelphia, PA since 1932(just a short distance from the Philadelphia Museum of Art, where Sylvester Stallone as 'Rocky' ran up the steps during his training) - is also a 3-cylinder ! Interestingly, it was also built in 1926. Despite my having seen it there something like 8 or 10 times - including its perpetual back-and-forth trip of about 20 feet - I never knew that before, nor do I recall any signs or other mention of that feature. For more details, see -
http://www.steamlocomotive.com/3cylinder/#60000
That 'webpage' has a couple of other links, the most valuable of which for this group would be this one -
THIS PUBLICATION CONTAINS, ON PAGES 2 TO 59, A REPRINT OF A BOOKLET ISSUED IN 1927, GIVING A DESCRIPTION OF THE LOCOMOTIVE AND RESULTS OF TESTS MADE ON THE PENNSYLVANIA RAILROAD STATIONARY PLANT AT ALTOONA. THESE TESTS WERE CONDUCTED DURING THE MONTHS OF AUGUST AND SEPTEMBER, 1926. DURING THE PERIOD OCTOBER, 1926, TO FEBRUARY, 1928, THE LOCOMOTIVE WAS OPERATED IN ROAD TESTS ON THE PENNSYLVANIA RAILROAD, THE BALTIMORE & OHIO RAILROAD, THE ERIE RAILROAD, THE CHICAGO, BURLINGTON & QUINCY RAILROAD, THE ATCHISON, TOPEKA & SANTA FE RAILWAY, THE SOUTHERN PACIFIC LINES, AND THE GREAT NORTHERN RAILWAY. THE GENERAL RESULTS OF THESE TESTS, AS FAR AS THEY HAVE BEEN MADE AVAILABLE BY THE RAILROAD COMPANIES MENTIONED, ARE PRESENTED ON PAGES 60 TO 80 OF THE PRESENT PUBLICATION.
at - http://www.cwrr.com/Lounge/Reference/baldwin/baldwin.html
And then this one, which includes an extensive descriptions and commentary by a man who was familiar with their construction, including a couple of the photos of the partially assembled mechanism -
at - http://www.cwrr.com/Lounge/Reference/baldwin/part01.html
Another unusual aspect of this locomotive is that it was a compound - the center cylinder was the high-pressure cylinder, and the outer 2 were the low-pressure ones.
See in particular the following photos of the mechanism, after paragraph 16. -
Cylinders:This is a rear view of the one-piece cylinder casting completely finished and drilled, with the truck center-pin in place.
http://www.cwrr.com/Lounge/Reference/baldwin/fig7.jpg
Guides and Crossheads:This view shows the light design of crosshead used, also the method of supporting the outside guides on bearers at each end.
http://www.cwrr.com/Lounge/Reference/baldwin/fig8.jpg
And the following after paragraph 19. -
Crank Axle and Wheels Assembled:This is the second pair of driving wheels, the outside cylinders being connected to the third pair. The axle is built up of five pieces.
http://www.cwrr.com/Lounge/Reference/baldwin/fig10.jpg
End View of the Completed Crank Axle:The crank cheeks are of cast steel, each made in one piece with a counter- balance weight which is cored hollow and filled with lead.
http://www.cwrr.com/Lounge/Reference/baldwin/fig11.jpg
After paragraph 21. - Plan Elevation of Valve Motion, at -
http://www.cwrr.com/Lounge/Reference/baldwin/fig13.gif
and Side Elevation of Valve Motion, at -
http://www.cwrr.com/Lounge/Reference/baldwin/fig13a.gif
Finally, here's the link to the Franklin Institute's webpage for its 'Train Factory' permanent exhibit = the modern version of the Railroad Hall.
http://www2.fi.edu/exhibits/permanent/train-factory.php
Since I haven't seen that in person yet, I can't comment on whether it's good, bad, or indifferent, etc. - although it seems that No. 60000 still has a starring role.
Hope you find this to be of interest.
- Paul North.
Kootenay Central Back in the Sixties? in Trains Magazine, there was an article on Mexican Steam. Therein was a roster of various locomotives and they had several 3-Cylinder locomotives. Three 3 Pacifics of Alco design were built in Canada at Montreal Locomotive Works for Mexico and they had operated into the Sixties, possibly the last 3-Cylinder rod locomotives in service on North America? [snip]
Back in the Sixties? in Trains Magazine, there was an article on Mexican Steam.
Therein was a roster of various locomotives and they had several 3-Cylinder locomotives.
Three 3 Pacifics of Alco design were built in Canada at Montreal Locomotive Works for Mexico and they had operated into the Sixties, possibly the last 3-Cylinder rod locomotives in service on North America? [snip]
CSSHEGEWISCH As long as we're on the topic, why did the IHB buy the U-4a's? Three cylinders and their sheer size seem to be a bit much even for a heavy switcher.
Yep - as I surmised, DPM's essay says pushing 6000 tons up the 2.2 % grade at the Gibson (Ind.) yard hump at a relentless 2 MPH - 89,500 lbs. of tractive effort with the booster cut in.
I suppose they'd be pretty good at 'creeping' a modern unit coal train under a 'flood' loader, too . . .
BNSFwatcher [snip] It has a 'booster' engine on the lead tender truck. Q #1: what kind of noise did those booster engines make? Q #2: were any of the U4a's ever lettered "New York Central". Tnx for any info. Hays
Hays
#1. I've never heard one in real-life - not even a recording - but I'd say it's likely not much noise that you could discern. Probably depends on/ varies with the design/ manufacturer of the booster - Bethehem ? Franklin ? others ? Also, whether it is 1 or 2-cylinders - both of which had to be fairly small to fit into the tender truck, hence small exhaust volume, hence less noise. Finally - does the booster exhaust at the tender - which might be audible if you were standing there/ riding on it, or back up through the main stack - which would be more plumbin but would assist the draft - and likely be drowned out by the 2 or 3 larger main cylinders.
#2. I'm not an authority, but - As far as I know, only on models and in the ads in the magazines.
Ok, wow, appears I opened a can of worms there...
Yes, much of what we read today, 50 years after the fact, written by folks who likely were not there and perhaps were unable to interview the survivors who actually were there, can be of questionable accuracy.
I think it is true that there were cases when the individual railroads were so proud of "the way we do things" that they failed to notice when a competitor had a great motive power solution to the same problem they faced.
Perhaps much of Mr. King's article was then just his personal opinion?
One interesting point that Kratville and Bush make is that Otto Jabelmann wanted diesels--but he also knew the UP wasn't going to get them--and only once it became very clear that there would not be enough diesels allocated to Union Pacific (Santa Fe got the lion's share of the FT's with zero going to Union Pacific or Southern Pacific) did they move ahead with the Big Boy design.
If GM had the ability or government authorization to deliver more FT's there most certainly would have been no Big Boys at all and no improved (second 3930 and up) Warbaby Challengers.
Edit: UP management above Jabelmann was not sufficiently impressed with the FT, so likely didn't press to acquire any. Jabelmann realized it would be years before diesels acceptable to UP management would be available in sufficient quantities to take over mainline duties--so he had no choice but to go ahead with his personal "Plan B"--design and build Big Boys, etc. UP management above Jabelmann was so enamored with steam power (in 1939 and 1940) that they directed him to come up with a sketch plan and estimate to rebuild the 4-12-2 into a modern articulated (a 4-6-6-2 concept resulted). The estimated cost was $166,600--too high relative to the cost of a new Challenger--and only the 10 4-12-2's that had developed significant frame cracking issues by 1939 were planned for conversion.
John
UP 4-12-2as either Trains or Classic Trains documented a year or so ago, many times the builders sold engines to the railroads that perhaps were more than what the railroad really needed for a given task--engines that sometimes made the builder much more money to build.
In fairness to Mr King, we should recognize that he had moved a step beyond earlier Trains writers-- he had realized that the railroads' obvious stupidity did call for an explanation, which he tried to supply.
2 Qs here: I have an 'O-scale' model (IHM? Rivarossi?) of IHB U4a 0-8-0 #102. I built it while stationed in the Canal Zone and painted it with purloined GI truck spray paint. It looks really cool. I just wish I had motorized it, but... It has a 'booster' engine on the lead tender truck. Q #1: what kind of noise did those booster engines make? Q #2: were any of the U4a's ever lettered "New York Central". Tnx for any info.
UP 4-12-2 a table that was allegedly supposed to be in the book that described changes to the gresley gear over time, but I found no such table.
yeah--the one great advantage of 3-cylinder power is the smoother application of torque and the greater ability to get power to the rail while still keeping axle loadings within reasonable limits.
Otherwise, the high speed simple articulateds that came later were an improvement for mainline uses.
Also, as either Trains or Classic Trains documented a year or so ago, many times the builders sold engines to the railroads that perhaps were more than what the railroad really needed for a given task--engines that sometimes made the builder much more money to build. There was the whole male ego issue of building and selling large steam power...which made it easy to sell the next big monster/latest greatest thing. Also, many times the builders' sales people wined and dined the railroad personnel to get the sales.
It has been suggested by some that the 2-6-6-6 as designed by Lima was really more than what C&O needed--or perhaps that more 2-10-4's or better utilization of the power they had might have been a better monetary investment. The 2-6-6-6 was a marvelous engine in so many respects--but was more than what C&O needed for many of the assignments. They found out rather late what a truly magnificent machine they had--which they had somewhat under-utilized.
Hump duty, as I recall from that DPM essay - pushing cuts of 100 to 150 cars at a time up the lead to the yard hump, at a very slow and steady speed - where the more constant torque added by the 3rd cylinder would be a decided advantage over a 2-cylinder locomotive.
As long as we're on the topic, why did the IHB buy the U-4a's? Three cylinders and their sheer size seem to be a bit much even for a heavy switcher.
timzIf it's a "three count", how can it be even? If it's even, what makes it three instead of five or nine or twenty-nine?
Even in that every beat is of similar strength and duration. Additionally, the 3 cylinder design would have more of a 6 part beat because there's 2 exhausts per cylinder, so more like 1-2-3-4-5-6. But, as 4-12-2 mentioned, the 9000s had differences in time and strength to their beats. It was more like 1--2-3--4--5-6.Beats 1 and 4 weren't in time with beats 2,3,5 and 6.
-ChrisWest Chicago, ILChristopher May Fine Art Photography"In wisdom gathered over time I have found that every experience is a form of exploration." ~Ansel Adams
CopCarSSA three count can be very, very even.
My guess is a three-cyl engine was supposed to be even, all exhausts at equal intervals, no cyclic sound at all. Question is, how often did they achieve that? Maybe not often at all, in the US, but maybe they did manage it in England or Europe?
In music the beat has to be the same regardless of where the measure line is placed otherwise the group will not be able to play or sing together.
In jazz some beats or fractions of a beat are "stretched" while others are "shortened"--which gives the "swing" feel--but the overall beat usually remains the same speed within a section of a song.
A waltz has a different feel because the primary beat (one of any measure) is made of muliples of 3 rather than 4, but the underlying speed has to be consistent or the group will self-destruct.
UP 4-12-2But the real 9009 was suffering from significant wear at the time of the recording which made it sound worse than the "typical" offbeat exhaust.
Ah ha...this makes more sense to me. It'd be the same as if valve wear was affecting a conventional 2 cylinder loco. What threw me was the "even 1-2-3 1-2-3" beat described on steamlocomotive.com.
Thanks for the clarification.
timz CopCarSS "a very even 1-2-3, 1-2-3 beat." 1-2-3 1-2-3 1-2-3 sounds like a description of an uneven beat. Hard to figure what they meant.
CopCarSS "a very even 1-2-3, 1-2-3 beat."
The description given on Steamlocomotive.com sounds very "waltzy" to me. A three count can be very, very even. It's just that I've never heard of 9000s described that way.
There is a reach rod from the gresley lever.
No diagram was shown illustrating what changed.
I was responding to comments above that the timing of the middle cylinders did indeed change over the years--though apparently not by all that much.
I was looking for a table that was allegedly supposed to be in the book that described changes to the gresley gear over time, but I found no such table. (that doesn't mean it's not there--some drawings were reproduced at a very small scale).
The types of bearings used with the gresley gear did change, as well as the shape of the lever itself, over time. It appears most changes were minimal, and drawings of all changes were not prepared by the UP mechanical staff--only documentation exists that there were changes.
There were many changes to the engines the authors did not intend to document or would never be able to document because records are scarce.
The "reach rod" is the thing outside, on the engineer's side, connecting the reverse lever in the cab to the right-side valve gear-- right? You can't alter just the middle cylinder events by changing the reach rod, can you?
Come to think of it, seems like changing just the reach rod wouldn't change the outside-cylinder events either. They didn't say what they meant by "reach rod"?
And they didn't say what angle changed by 2 degrees?
I was quoting from Kratville and Bush.
As I said above--it was the middle cylinder, and it was the valve event that changed by 2 degrees. Changing the length of a reach rod or the bearing position/type of bearing is going to affect the valve timing. There were changes over the lives of the engines. Not all are documented.
I'm not a mechanical engineer, and it would be helpful to actually be one to understand the highly technical nature of the books (and small scale drawings).
I'm a dumb civil engineer--we only design things that do not move or rotate (excepting certain movable bridges).
Forgive my ignorance.
UP 4-12-2 the length of the reach rods was changed
UP 4-12-2It is not 2 degrees of driver rotation
UP 4-12-21-2-3 can be "even" just as much so as 1-2-3-4.
I'm not a mechanical engineer, but the length of the reach rods was changed, among other things that also changed--all of which affected valve timing.
It is not 2 degrees of driver rotation--the valve events do not exactly correspond to degrees of driver rotation--there are other levers, etc. in between.
Uh, I play trumpet as a hobby and sometimes even get paid to do it!
1-2-3 can be "even" just as much so as 1-2-3-4. "Even" would mean equal spaces of time between beats.
However, even MTH's HO model of the 4-12-2 has an uneven 1--2-3 4--5-6 beat, where the beats 1 and 4 are stronger, and 2/3 and 5/6 are faster/closer to each other--out of sync. At higher speeds the exhaust becomes more regular--perhaps due to sound distortion/blurring.
But the real 9009 was suffering from significant wear at the time of the recording which made it sound worse than the "typical" offbeat exhaust.
At low speeds the sound is quite interesting and enjoyable as something different on the train layout.
UP 4-12-2The final 25 engines...had different middle cylinder valve events by 2 degrees than the previous 4 groups
If they did have the usual levers, how could the valve events have been changed?
Chris and Paul--
There allegedly are other recordings of the 4-12-2, including apparently another one on the same Howard Fogg album as the link above, but I've never heard them and do not know if they are available on cd.
I've found 3 dvd's that have 4-12-2's on them, but none have sound, and 2 of them only show a couple scenes with 4-12-2's. The best dvd by far is Greg Scholl's Union Pacific Steam Classics, Vol. 1, which includes several minutes of footage with plenty of runbys in Kansas and Nebraska (all with a tasteful music soundtrack as no sound is or was available at the time the video was being edited).
During the last 2 nights I searched through more than 100 pages devoted just to major changes during their service lives on the 4-12-2's in the UP Type, Vol. 2, and the changes to the Gresley gear were mentioned only in passing. The final 25 engines which were built with complete one piece cast frames and integral cylinders had different middle cylinder valve events by 2 degrees than the previous 4 groups of 4-12-2's--but the authors could find no solid evidence that definitively explained the reason(s) why. It is also unknown why 5078, 5080, and 5086 had their valve events changed to match the previous 4 groups of 4-12-2's.
Of course, during the steam era, running changes and improvements were constant. Not all 88 engines ever received all the improvements.
Which brings me to the next point:
Paul, there were 88 UP 4-12-2's and only 10 TOTAL 4-10-2's. After rebuilding to 2-cylinder configuration during the 1940's, they were renumbered into the higher end of the 2-10-2 number series as engines 5090 to 5099, and were generally considered comparable to a 2-10-2 in future assignments, etc.
The maximum horsepower of a 4-12-2 was nominally 4900 horsepower (4917 at 37 mph as tested on the original engine number 9000 during 1926). This was nominally the same as the first group of Challengers. UP tonnage ratings for 4-12-2's and the first group of challengers were the same. Otto Jabelmann hated the 4-12-2's due to the maintenance issues, but the operating department and officials in New York loved them because they slashed overall costs and schedules (even though maintenance was higher)--and they ultimately were too big of a group of engines to rebuild or scrap (even though Jabelmann wanted to get rid of them as early as 1940, they were essential--they would have needed 88 more Challengers to replace them).
1926 was the watershed year for 3-cylinder power because it quickly became known within the railroad design industry that superpower designs such as 4-8-4's or even 4-6-6-4's would be a less maintenance-intensive solution to the need to speed up freight schedules. As Kratville and Bush said, the 4-12-2's were a bridge between the slow drag freight era and the superpower era that came after them. Had they received roller bearings, their performance and durability would most certainly have been greatly improved.
By the late 20's the 3-cylinder solution had been eclipsed--only UP's operating department was so happy with them that they kept buying more through 1930.
UP 4-12-2 [snip] William Kratville and John Bush wrote two excellent books on the UP 4-12-2 that also include much information on the UP 4-10-2 (both as built and as later rebuilt). They are among the finest books ever written on any locomotive type, and are filled with lots of drawings and engineering data, and interviews with the men who designed, built, and maintained them. [snip]
From the Union Pacific Historical Society's ''Library'' webpage, at - http://www.uphs.org/library/engines/ -
Vol I - ASIN: B0006EV8Y2 - was apparently published in 1990 - it appears to be available for about $220 to $370 from Amazon.com today.
Vol. II - ASIN: B000TXPA26 - was apparently published in 1995 - it appears to be available for about $65 to $85 and up from some booksellers.
EDIT - Somewhat surprisingly, at least 1 Pennsylvania library has this book. Here's the catalog data on it, in case it will help anyone else find it
[Omaha, Neb. : AutoLiner], c1990-c1995.
Alt Author Bush, John E.
J V Brown Lib Williamsprt - Call Number/Serial Holdings - 625.261 KRA V.2
Three Barrels of SteamJames E. BoyntonGregg Glenwood Publishers, Felton, Ca. Hardbound 160 pages Information on the three cylinder 4-10-2 locomotive UP/LA&SL 8800's
UP 4-12-2 The middle cylinder had a different length of stroke than the outside cylinders, so this would have contributed to the off-beat rhythm. Also--there is a lot of misinformation about the 4-12-2's even quoted in usually fairly reputable online sources like www.steamlocomotive.com. For example, the middle cylinder on the UP 4-12-2's was inclined at 9.5 degrees and not 8 degrees as often reported. (Kratville and Bush, UP Type, Vol. 1) William Kratville and John Bush wrote two excellent books on the UP 4-12-2 that also include much information on the UP 4-10-2 (both as built and as later rebuilt). They are among the finest books ever written on any locomotive type, and are filled with lots of drawings and engineering data, and interviews with the men who designed, built, and maintained them. Kratville and Bush discuss the offbeat exhaust. In addition to having a shorter stroke (31" versus 32" of the outside cylinders), they say the valve events were different--which also contributed to the offbeat sound. The UP wanted much faster locomotives able to pull a much longer train much farther distances. Alco believed the 4-12-2 should be only a 35 mph standard operating speed locomotive. UP, as well documented by Kratville and Bush, had absolutely no intention of operating 4-12-2's at 35 mph, but planned from the outset to operate at significantly higher speeds--regardless of what Alco's recommendations were--they were trying to slash schedules and speed up trains as Santa Fe was already doing. Additionally, the UP was facing a traffic crunch and somewhat rushed the testing period of the "demonstrator" 4-12-2, number 9000. The operating department was absolutely thrilled with the dramatic cost savings and speed/tonnage increases of the 9000 relative to all previous motive power--so any and all concerns about increased maintenance costs were greatly outweighed by the overall freight schedule improvements. Unfortunately, the 4-12-2's were not designed with as much consideration to long term maintenance as perhaps they should have been, and there was much pressure within the UP operating department to keep them on the move--such that maintenance of the middle cylinder often suffered. The UP 4-12-2's lasted till very nearly the end of all steam on the UP, and even as late as 1952, the engineering department planned to keep the last 25 4-12-2's (which had one piece cast frames) operating through the targeted end of steam, estimated to occur during 1965. Subsequent events (nationwide recession) and diesel deliveries moved the end up by several years. John
Also--there is a lot of misinformation about the 4-12-2's even quoted in usually fairly reputable online sources like www.steamlocomotive.com. For example, the middle cylinder on the UP 4-12-2's was inclined at 9.5 degrees and not 8 degrees as often reported. (Kratville and Bush, UP Type, Vol. 1)
William Kratville and John Bush wrote two excellent books on the UP 4-12-2 that also include much information on the UP 4-10-2 (both as built and as later rebuilt). They are among the finest books ever written on any locomotive type, and are filled with lots of drawings and engineering data, and interviews with the men who designed, built, and maintained them.
Kratville and Bush discuss the offbeat exhaust. In addition to having a shorter stroke (31" versus 32" of the outside cylinders), they say the valve events were different--which also contributed to the offbeat sound.
The UP wanted much faster locomotives able to pull a much longer train much farther distances. Alco believed the 4-12-2 should be only a 35 mph standard operating speed locomotive. UP, as well documented by Kratville and Bush, had absolutely no intention of operating 4-12-2's at 35 mph, but planned from the outset to operate at significantly higher speeds--regardless of what Alco's recommendations were--they were trying to slash schedules and speed up trains as Santa Fe was already doing.
Additionally, the UP was facing a traffic crunch and somewhat rushed the testing period of the "demonstrator" 4-12-2, number 9000. The operating department was absolutely thrilled with the dramatic cost savings and speed/tonnage increases of the 9000 relative to all previous motive power--so any and all concerns about increased maintenance costs were greatly outweighed by the overall freight schedule improvements. Unfortunately, the 4-12-2's were not designed with as much consideration to long term maintenance as perhaps they should have been, and there was much pressure within the UP operating department to keep them on the move--such that maintenance of the middle cylinder often suffered.
The UP 4-12-2's lasted till very nearly the end of all steam on the UP, and even as late as 1952, the engineering department planned to keep the last 25 4-12-2's (which had one piece cast frames) operating through the targeted end of steam, estimated to occur during 1965. Subsequent events (nationwide recession) and diesel deliveries moved the end up by several years.
Brian Reed's article in Vol. 2 of his 1970's Locomotives in Profile series echoes and supports almost everything that UP 4-12-2 wrote above as exactly correct - except that this took about 2 less pages ! Reed's article devoted itself mostly to the novelty and success of this 12-coupled design, that it was the longest rigid wheelbase except for ''a solitary semi-mythical Russian 4-14-4'' as he put it [for more on that strange beast, see - http://home.att.net/~berliner-Ultrasonics/bw-apoc4.html#russki14 ], the lateral motion devices, etc., and less to the 3-cylinder aspect of it. A couple of supplemental comments may be of interest here:
- The inside 3rd cylinder drove a crank axle on the 2nd pair of drivers, while the outside 2 cylinders drove the 3rd pair; hence it was a 'divided drive'. The reason for this arrangement was that for the tractive effort and power that UP wanted from this design for the reasons stated above, all of that driving on 1 axle would have been too much. All of the cylinders were 'simple' = direct from the boiler (no compounding);
- The first axle apparently was not 'offset' or bent or 'cranked' to clear the drive rod to the 2nd axle, as I stated a few posts above - I misread/ misunderstood that. UP and ALCO avoided that by using the 67'' driver size - 63'' was first planned for, the 18'' increase in spacing between the 1st and 2nd pair of drivers to 88'', and the slight shortening of the inside cylinder stroke from 32'' to 31'' as noted above;
- The primary reason for the 6 axles was UP was limited to a 59,000 lb. axle loading. Despite that, the pilot and trailing trucks carried 60,000 lbs. ;
- 1926 must have been a 'watershed year' for 3-cylinder designs, what with UP's and the DRGW's noted above. The UP's fleet eventually numbered 88, which Reed says was 1/3 of all US 3-cylinders. Since UP had a predecessor fleet of 49 3-cylinder 4-10-2's, it seems that UP had the majority of them;
- The 4-12-2 fleet lasted 30 years in main line service until 1956, including after the advent of the 4-6-6-4 Challenger and 4-8-8-4 Big Boy designs and a substantial fleet of diesels, so the UP must have been satisfied with them.
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