Re: 1937 AAR boxcars: Dreadnaught corner posts

Robert kirkham

Hi Irv,

I think the key thing to keep in mind is that the ends were proprietary to a parts manufacturer, not to any one railroad.  So like you car, it has the look of the year it was bought.  It's more complex than that, but you can probably find several references if you search the archives using the word dreadnought.  I have forgotten what I’ve read on the topic.  For a given date, I think it probably matters which plant was manufacturing one end or another.  For the CNR, I imagine a certain percentage of their purchases were from Canadian licensed manufacturers, and those folks may have been constrained to stay with older tooling for longer as the war was already underway up here. 

But my comments are only inference and reflecting what I have read over the years, not detailed observation or analysis.


On Dec 30, 2020, at 7:21 PM, irv_thomae <irvthomae@...> wrote:

I've been carefully studying the Ed Hawkins/Ted Culotta tabulation covering almost 93,000 AAR boxcars built between 1936 and 1947.  Having chosen long ago to model the time period from fall 1940 through summer 1941, and wanting only a few newly built cars on my back-country layout, I highlighted each group of cars built before 1940 in green, and each group built in 1940 in yellow.
  Doing that led to an interesting discovery about cars built with the standard 4-5 Dreadnaught ends:  The vast majority of those built before 1940 had square-cornered ends.  As of January of 1940, there was a dramatic transition to round-cornered ends, also known as "W corner-post."   Apart for the CN, which stayed with square corner posts through March of 1940, it appears that fewer than a dozen more cars were built with square corners from 1-40 onward, for even the smallest railroads.
  Rapid changes were not exactly common in prewar railroad engineering practice.  Does anyone happen to know why this transition, from square corner posts to the 'W' type, happened to quickly?   Was it driven by regulatory action, perhaps in response to safety issues?  Or were there dramatic savings either in weight or fabrication cost?
   And, did otherwise very similar cars with the two different corner post types show a consistent weight difference?

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