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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
  • 9,728 posts
Posted by Flintlock76 on Monday, January 25, 2021 5:42 PM

I went looking through the archives here at the "Fortress Flintlock" and all I could find out about the 60,000 pound axle loading was in "Alfred the Bruce's"  Wink  book "The Steam Locomotive In America."  Apparantly the 60,000 pound axle load (and not above that figure) was specified by the Union Pacific, but Bruce doesn't say why. 

Another book I've got on American steam development doesn't say why either.

Maybe it was  due to the track it was going to run on.  Those 4-12-2's were smooth-running locomotives though, however due to that long rigid wheelbase they were restricted to mainline runs and trackage with very gentle curves. 

I'll keep looking.

I did.  Can't find nuthin' else.  Sorry.

  • Member since
    September 2003
  • 21,669 posts
Posted by Overmod on Sunday, January 24, 2021 11:02 PM

I believe Juniatha had a particular interest in the Nines and would be an ideal source for this kind of information on them.

  • Member since
    July 2004
  • 2,741 posts
Low axle loadings on the 4-12-2 Union Pacific-type locomotives (9000 series)
Posted by Paul Milenkovic on Sunday, January 24, 2021 7:51 PM

Anyone know why the driver axle loadings on the 4-12-2's were substantially lower (below 60,000 lbs/axle) than on the 4-6-6-4 Challengers?

I wouldn't think with the long rigid wheelbase (yes, with lateral motion devices, but still) would be amendable to anything else but main lines with gentle curves?  Was the UP using lighter rail on their network into the 1920's when the 9000-series locomotives were introduced?

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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