On Dec 14, 2018, at 2:38 PM, main@RealSTMFC.groups.io wrote:

5a. Hollow Bored Axles
From: Bob Chaparro <chiefbobbb@verizon.net>
Date: Fri, 14 Dec 2018 14:29:51 EST

This hopper was constructed with aluminum sheets:

http://www.burlingtonroute.org/BRHS/library/photo_collections/viewer.php?library=Historical&;folder=Rolling_Stock-freight&image=34 (http://www.burlingtonroute.org/BRHS/library/photo_collections/viewer.php?library=Historical&;folder=Rolling_Stock-freight&image=34 )

A stencil on the car reads "Hollow Bored Axles Standard To Car. If Replaced With Solid Axles Notify Owners At Once."

What is the story on hollow bored axles?

Bob Chaparro

Hemet , CA

According to Bob Karig's "Coal Cars: The First 300 Years" the hollow axles were an effort to reduce unsprung weight as they weighed 30% less than solid axles. Trials were run in 1941 and 1946 AAR rules "standard tubular axles" were permitted as a standard alternate to solid axles. In 1961 the alternate was removed and tubular axles were prohibited on interchange cars 1 Jan 62.

Craig Zeni
Cary NC