Were the Challenger 4-6-6-4 were REALLY developed from the 2-6-6-4.
It was the articulation of the Union Pacific-type 4-12-2 as I understand it. Per William Kratville’s book “The Challenger Locomotives”, General Mechanical Engineer Arthur Haldeman Fetters oversaw design of the type. Union Pacific President William Jeffers named the type in reference to the assignment to run the locomotives unassisted from Ogden to Wasatch and continue on to Green River and then return with another train to Ogden.
Here are a couple of links for comparison of the UP 4-12-2 and the UP "Jeffers" (correction - “Fetters” 4-6-6-4:
http://digital.denverlibrary.org/cdm/ref/collection/p15330coll22/id/49692
https://www.railarchive.net/bigboys/images/up3838_dvl.jpg
Speaking of UP Class CSA-1 / CSA-2, some railfan calling them "early challenger" or "original challenger", they are my favorite version of Challenger type as well as the articulated steam engine!
I wonder which named train was towed behind the engine in these pics!
Jones 3D Modeling Club https://www.youtube.com/Jones3DModelingClub
Interestingly, the UP had a named train called "The Challenger," although I doubt it had anything to do with the locomotive type. My father rode it in 1946 when he was in the army and on his way to occupation duty in Japan.
Whether it's the train behind the locomotive in the picture is anyone's guess.
To answer the op question. The Challenger type was a direct development off the 4-12-2 Union Pacific type the longest rigid wheelbase locomotives ever built the center 2 wheels were blind no flanges. They had 3 cylinders on them. UP needed something better however and went to Alco to see what they could come up with. Alco suggested a simple articulation 4-6-6-4 and they worked wonders.
Flintlock76 Interestingly, the UP had a named train called "The Challenger," although I doubt it had anything to do with the locomotive type. My father rode it in 1946 when he was in the army and on his way to occupation duty in Japan. Whether it's the train behind the locomotive in the picture is anyone's guess.
UP built the Sun Valley resort in Idaho. The Sun Valley Inn was originally called the Challenger Inn.
Just did some brief research. UP used the Class CSA-1 and CSA-2 to haul the Portland Rose before the introduction of diesel streamliner.
The first 2-6-6-4 types were built for Pittsburg and West Virginia in 1934. Then N&W built their first two in 1936 at the same time Alco was building the 4-6-6-4s for UP. Did Alco compare any notes with Norfolk & Western? Or is this a case of parallel development?
SSW9389 The first 2-6-6-4 types were built for Pittsburg and West Virginia in 1934. Then N&W built their first two in 1936 at the same time Alco was building the 4-6-6-4s for UP. Did Alco compare any notes with Norfolk & Western? Or is this a case of parallel development?
I've never heard of their being communication between UP and N&W during development of the 1936 Challenger locomotive. Otto Jabelmann, who was in charge of UP motive power development at the time, was studying the high speed articulateds that had just gone into service on the Seaboard Air Line (2-6-6-4) and B&O (2-6-6-2). These were simple articulateds with tall drivers--the same formula UP followed with its Challengers and Big Boys.
Scott Griggs
Louisville, KY
Folks, this is getting a bit nutty.
The original (CSA) Challengers are not "Jeffers" Challengers, they are FETTER Challengers, after Arthur H. Fetter, who is actually the one who in conjunction with Alco principally designed them. (Jabelmann would have his chance a couple of years later, and do quite well both with Challengers and their only slightly enlarged relations, the 4-8-8-4s). [EDIT - Thanks for the corrections - I called these "Fetters Challengers" for years, based on Kratville's pratfall, and only found out the correct spelling after the Internet 'brought it to my attention'. Then I had to make periodic Google searches to reinforce the correction for quite some time, as "Fetters Challenger" was the phrase I'd been used to seeing to describe the class...]
The original high-speed articulated locomotive is probably the Baldwin proposal to Erie (for what is basically an AMC-Berk-and-a-half) in late 1929. This presumably shared design details with the first practical high-speed articulateds in the world, the Baldwin 2-6-6-2s of 1930 (which were not entirely successful for a variety of reasons that are clear when you reflect on them a while). The P&WV 2-6-6-4s are actually a step backward in this respect, as they're manifestly not a high-speed-optimized design; the Seaboard locomotives are the great ground-breakers, which I believe is acknowledged in the history of the N&W A.
Note that there are more differences than similarities in the design details of the 4-6-6-4 vs. the 2-6-6-4. Union Pacific wanted to retain the high-speed dynamics of the four-wheel lead truck, which in turn would have made the locomotive much longer and thrown off the weight distribution had a typical Super-Power deep firebox been used. Instead, the Fetter Challenger (and all other classes of Challenger) had shallower fireboxes with the forward portion over the rear driver pairs, which reduced both the radiant surface and relative combustion efficiency (there were some other issues). Bruce at Alco was proud of the suspension arrangement on the Challengers, which eliminated the vertical-hinge issues with Mallet-type articulateds at high speed by using the equalization alone (over the six driver pairs plus leading truck) to accommodate vertical changes and providing solid frame contact to the forward engine; however, King pointed out that N&W had essentially done the same thing for the same reason (albeit with somewhat different means) on the independently-developed A locomotives.
My bad on the Jeffers thing. I own and have read multiple books on the Challengers multiple times and know that Arthur H. Fetters (William Kratville has it as Fetters) did the designing. It was a case of brain-lock after a 12-hour work day. Mea culpa, mea culpa, mea maxima culpa.
An interesting read is "World's Greatest Steam Locomotives" by Dr. Eugene Huddleston. He examines and compares the UP 4-6-6-4 to the N&W 2-6-6-4.
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BigJim - +1 on that. I have that one in my library also!
As I recall there's a Challenger at the Henry Ford Museum in Dearborn. Worth visiting for that and much else.
54light15As I recall there's a Challenger at the Henry Ford Museum in Dearborn. Worth visiting for that and much else.
It is actually the C&O 1601
https://www.thehenryford.org/collections-and-research/digital-resources/popular-topics/allegheny-locomotive
Never too old to have a happy childhood!
The Jabelmann Challengers were only about 9 feet longer than the Fetters Challengers, but for some reason they looked much larger. Perhaps it was the bigger front platform and the larger tender, with 25,000 gallons of water capacity in the 4664-3, 4664-4 and 4664-5 classes versus the 18,106 gallons of water capacity for the CSA-1 and CSA-2 classes.
The Jabelman Challenger engine and tender weight reached 1,069,000 lbs in the 4664-5 class, while the CSA-1 and CSA-2 classes weighed 889,550 lbs.
Yet tractive effort was about a wash, at a calculated 97,352 for the Jabelmann Challengers and 97,305 for the Fetters Challengers.
Here is a Fetters Challenger for comparison:
http://digital.denverlibrary.org/cdm/singleitem/collection/p15330coll22/id/56588/rec/104
Here is a Jabelmann Challenger for comparison:
http://digital.denverlibrary.org/cdm/singleitem/collection/p15330coll22/id/56640/rec/147
BaltACD 54light15 As I recall there's a Challenger at the Henry Ford Museum in Dearborn. Worth visiting for that and much else. It is actually the C&O 1601 https://www.thehenryford.org/collections-and-research/digital-resources/popular-topics/allegheny-locomotive
54light15 As I recall there's a Challenger at the Henry Ford Museum in Dearborn. Worth visiting for that and much else.
Just a wee bit bigger than a Challenger, maybe even larger than a Big Boy.
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