Re: USRA single sheathed box cars flooring questions

Jack Mullen

The construction you describe, with flooring extending under the side sheathing,  is common for stock cars and composite gons, but I don't know of any SS boxcars built that way.  From builder's photos, most if not all of the USRA SS cars had a pressed steel angle riveted to the top of the side sill to form an attachment for flooring, and perhaps retain the sheathing as an alternative to bulge plates.  A narrow ( perhaps 1 1/2" or 2") flange extends upward outside the lowest board of the side sheathing. A wide flange extends toward the center of the car and has holes for floor bolts. See photo on p.8, RPC17.  The vertical flange along the bottom of the sheathing forms a narrow linear feature that could look like the ends of flooring in photos, but in a closeup or good hi-rez print you see that there aren't individual board ends, just a smooth strip.  Again, see  RPC17.

The bulge plates and flooring clips Dennis describes are shown of the GA drawing he cites, but don't seem to have been used in production. This appears to have been another design change between the early release of GA drawings and actual production. 

Many USRA cars did get bulge plates in later years.  A quick scan of published photos suggests that this construction was the norm for new construction by the mid-1920s.  I speculate that the USRA-type flooring angle may have been vulnerable to corrosion. Also, the need to have the bolt holes in the flooring align with pre-punched holes in the attachment angle would be a disadvantage compared to using floor clips.

Jack Mullen

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