Wooden boxcar sheathing


gpierson@...
 

Hello, all,

Based on a number of photos of boxcars that appears in the books on the PRR
put out by the PRR Tech & Hist Society (e.g., books on Pittsburgh and
Lewistown) taken around WW I that I have seen, there is pretty clear evidence
that parts of the vertical sheathing were replaced when needed - presumably if
they had been damaged or otherwise were beginning to give out. The result is
sections of a car side where the paint color is notably different than that on
the rest of the car. While this is photo evidence alone, I have had this
hypothesis corroborated by others knowledgable in car history. IOW re-
sheathing did not always involve the whole car side.

I was also 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


Tim O'Connor <timoconnor@...>
 

George, I think they were referring to the car's superstructure.

I was also 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

Tim O'Connor <timoconnor@attbi.com>
Sterling, Massachusetts


Garth G. Groff <ggg9y@...>
 

George,

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

gpierson@trnty.edu 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


thompson@...
 

Garth Groff wrote:
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...
Actually, the pulling forces were readily transmitted by a far lighter
underframe, as the Bettendorf design of ten years earlier had proven. The
deep USRA underframe was to carry the CAR loads. Think of that fishbelly as
the truss rods replaced by steel sheet.

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.
See above, regarding pulling forces. That the USRA design committee took
credit for the stiffness of the body framing of the single-sheathed car is
evident from the design, though that topic was one of lively debate at the
time. The rather conservative RR mechanical community of the time was
definitely divided about the appropriateness of doing so.
The DS car has a 26-inch deep center sill, the SS car, 12-inch deep sill.
The difference in stiffness terms is immense.

Tony Thompson Editor, Signature Press, Berkeley, CA
2942 Linden Ave., Berkeley, CA 94705 http://www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@signaturepress.com
Publishers of books on railroads and on Western history