Re: wood vs styrene (was a very short intro)


Dennis Storzek <dstorzek@...>
 

--- In STMFC@yahoogroups.com, Tony Thompson <thompsonmarytony@...> wrote:

Sounds good, Tim, but 'tain't so. Many flat car drawings show
interlocking or T&G planking; and every photo I've ever seen sure looks
like it is laid real tight. I've never seen any crown, either. Anyway,
most expansion from damp is along the grain, and that's across the deck
width, not along the deck from board to board.
I can't let this one pass uncorrected. You've got it exactly backwards, Tony; wood is relatively stable along the length of the grain, but shrinks and swells appreciably across the grain. This is useful for making barrels, water tanks, and hot tubs water tight; simply fit the boards to be a good fit when dry, then fill with water. As the wood swells, it expands against the steel hoops and tightens to the point that it doesn't leak.

How does this affect flatcar decks? It doesn't. Just like the barrel bands and tank hoops, the flatcar frame is so much stronger than the amount of pressure generated by the swelling wood that the wood just compresses. It doesn't tear loose from its fastenings because the fastenings are HUGE; 1/2" or 5/8" diameter bolts as I recall.

Why drain the deck at all? Railroad cars rarely sit dead level, and anyway the water will just shake or blow off a moving car. Years ago, when I worked for the transit authority, we always wedged or jacked platform decking tight; gaps between the boards were considered a tripping hazard. Evaporation was relied on to dry the deck surface.


Dennis Storzek

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