Re: Wooden boxcar sheathing

Garth G. Groff <ggg9y@...>


Yes, all USRA boxcars, both single and double-sheathed, had steel underframes. However, the body framing of the double-sheathed cars was wooden. Sorry if this wasn't clear.

If you take note of the designs, the double-sheathed USRA cars had a massive fishbelly underframe. It was made like this to transmit all the pulling forces through the underframe. The car body was really just a simple wooden box sitting on top of the underframe and had no part in the actual structural integrity of the car as a whole. Since it was made of wood, it was still subject to flexing, and also to damage caused by shifting loads. Because of this, many of the USRA DS cars were rebuilt with steel bodies in the 1930s, and except for ex-NYC TH&B cars, the large GN fleet, and a handful on the SP&S, most of the unrebuilt cars were gone by the early 1950s.

With the USRA single-sheathed cars, the body framing was part of the total structure of the car. The pulling forces were partially transmitted through the steel body frame, and so the underframe could be much lighter. This is the same principle that was applied to most steel boxcars, though steel sheathing plates replaced the side truss system.

Did I get this right, Tony and Richard?

Kind regards,

Garth G. Groff wrote:

Hello, all,
. . . I was puzzled by references in some recent messages to USRA boxcars having "wooden frames." I am under the impression that all the USRA cars were steel underframe.
George Pierson

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