John Meixel posted:Jack I assume he means the axles.
OK, well in that case, those are the cannon housings that contain/retain the roller bearing assemblies. The Union Pacific modern "Big Three" class of steam locomotives (800s, 3900s, and 4000s) all were built with roller bearings on all axles (engine and tender).
Unless he was referring to stuff on the floor around the UP wheel/axle sets.