Re: longevity of truss-rod cabooses?


Dennis Storzek
 

The Soo Line retired its last wood cabooses with truss rod underframes in the early 1980's, although they may have been out of service since the late 70's. Their last use was transfer cabooses in the twin cities and Chicago area, and with their last rebuilding, many had their cupolas entirely sheathed in plywood, so while the cupola was still there, it had no windows. However, this was the entire caboose fleet until the International Car Co. "wide vision" cars began arriving in the mid 60's.

IIRC, the ICC required steel underframes on all cabooses by 1928, although I'm not sure if that deadline was extended. The Soo complied, fitting their entire fleet of wood caboose cars with steel underframes in the early twenties. They essentially built new steel center sills, body bolsters and crossbearers, cleaned everything below the sills off the existing cars, and set them on the new frames. Since the truss rods also served to hold the end sills on the original frame, they were retained, with the two pairs of crossbearers properly located to serve as needle beams. The inner truss rods typically sat in short saddle castings riveted directly to the crossbearer cover plates, while longer queenposts were cast with a mounting flange that matched the angle of the lower surface of the pressed steel crossbearer. As far as I can tell, thy served no purpose on the rebuilt car (the short cars certainly didn't need the truss to support the middle) and simply held the ends on the body. It appears that the ICC order simply wanted steel sills of adequate proportion, and the fact that were these additional truss rods was not an issue.

Dennis Storzek

Join main@RealSTMFC.groups.io to automatically receive all group messages.