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Low axle loadings on the 4-12-2 Union Pacific-type locomotives (9000 series)

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  • Member since
    January 2019
  • From: Henrico, VA
  • 6,423 posts
Posted by Flintlock76 on Monday, March 1, 2021 3:19 PM

sgriggs
Without doing a small research project involving skimming many books on UP motive power history, I would say that the railroad upgraded their physical plant at some point in the early- to mid-1930s.  Rail or bridge ratings must have been a limiting factor up to this point.

Makes perfect sense.  Thanks!

  • Member since
    July 2004
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Posted by Paul Milenkovic on Monday, March 1, 2021 5:02 PM

sgriggs

All of the UP locomotive types I checked on Steamlocomotive.com up to the 1936 CSA-1 Challengers had axle loadings under 60,000 lbs.  This included the UP 4-12-2, the predecessor 4-10-2 3-cylinders, the 7000 class 4-8-2's, and the 2-8-8-0 'Bull Moose' compound articulateds.   It wasn't until the CSA-1 Challengers in 1936 that allowable axle loadings were increased to 66,000 lbs or so.  The 800 class 4-8-4's, debuting one year later, also had axle loadings around 67,000 lbs.

 

Without doing a small research project involving skimming many books on UP motive power history, I would say that the railroad upgraded their physical plant at some point in the early- to mid-1930s.  Rail or bridge ratings must have been a limiting factor up to this point.

 

 

Sounds quite plausible.

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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