02-10-2018, 10:56 PM
While the Southern's Su-class boxcars did have truss rods, they also had steel underframes.
Steel underframes were required on all cars built after Jan. 1, 1927, or re-built after July 1, 1928. All-wood underframes, including steel-girthed centre sills, were prohibited in interchange after Jan. 1, 1940, but truss rods on composite underfames weren't banned from interchange until Jan. 1, 1952.
Wayne
Steel underframes were required on all cars built after Jan. 1, 1927, or re-built after July 1, 1928. All-wood underframes, including steel-girthed centre sills, were prohibited in interchange after Jan. 1, 1940, but truss rods on composite underfames weren't banned from interchange until Jan. 1, 1952.
Wayne