Some of these may be a tad on the old side, but still interesting. Found the following goodies in Google Books:
Modern Freight Car Estimating:
Westinghouse Quick-action Automatic Brake Equipment
Freight Car Equipment: - Very nice illustrations...
Miller's Trussed Platforms, Compression Buffers and Automatic Couplers:
A Manual of Engineering Specifications and Contracts:

Jim Eckman

One problem w/ Google books is they don't yet accept that anything published
by the federal government has no copyright. There are gobs of ICC, Army
Corp of Engineers, and Bureau of Mines books in their listings -- all of
which have useful and interesting RR information, such as carloadings -- but
none of which is revealed beyond a single paragraph.

I've written to point this out and the reply I got was along the lines of
"We're trying to be real careful".

Dave Nelson