Re: from 40' 6' to 50' 6" box cars


water.kresse@...
 

"Forklift-proofing" made strength and thickness an issue on box cars. Part of Lt Wt is the addition of DF-type rails. Older 40-ft box cars had bulkheads and floor coverings put in their ends and on their wooden flors to ship heavy iron castings for the auto industry.

ALL GOOD FEEDBACK! Thanks guys. NOW I have to get the C&O Rwy Cost Sheets out and determine typical 40-ft to 50-ft box purchasing cost differentials.

Al Kresse

-------------- Original message --------------
From: Anthony Thompson <thompson@...>
AL Kresse wrote:
I agree on the Lt Wt issue. They experimented with 0.075" thk HSLA
steels just prior to the war and then re-upped the ga. again. HSLA
(then called high tensile) steel was used in side-sheets but at the
older std thicknesses.
This is a subtle point. The stronger steel is no STIFFER, so making
it thinner makes it prone to buckling, and that's what happened to some
box cars with thinner side sheets: wrinkling, etc. This can be solved
by adding intermediate posts between the regular side posts (that's the
so-called "Alternate Center Riveting" or ACR box car design), but then
the weight of the extra posts offsets the weight saving of the thinner
steel.
This emphasizes that much of structural design, including box
cars, is based on stiffness and not on strength. The best illustration
of that is the dreadnaught end. It is trivially STRONGER than a flat
end, but greatly STIFFER. The same goes for underframes, sides and
roofs.

Anthony Thompson
Dept. of Materials Science & Engineering
University of California, Berkeley
thompsonmarytony@...

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