@Rich Melvin posted:OK, Marty! Here we go. Thanks for the invite.
When a locomotive shop did a full overhaul on a locomotive's running gear, there were hundreds of bearing clearances that had to be right. The crown brass bearings on the axles, the main rod, the connecting rods, and the eccentric rod bearings, the bearings in the valve gear, the clearances in the crosshead, and several other points all had to be correct within a few thousandths of an inch. If even one of those clearances was off by a few thousandths, it would cause problems in the running gear. Those problems would typically show up in the form of excess bearing heating, as the "tight" bearing ran hotter than its neighbors. Conversely, a loose bearing will make noise that should not be there.
Running an engine for a few miles on a slip track allowed the shop forces to confirm that everything was right and that nothing was loose or running hot. Better to discover a problem in the yard on the slip track than 100 miles down the road somewhere, blocking the main track.
So how reliable is greasing the track? Was the locomotive contained some how in the case of actually grabbing the rail?
