Product information for the Bachmann 4-8-2 USRA Light Mountain loco suggests a 19 inch radius for good operation. In hidden sections of track (e.g. tunnels) the awkward apearance of long engines and carriages on tight curves is covered up and smaller radius curves might be possible. For these sections, what would be the smallest radius that a 4-8-2 could negotiate?
They handle 11" R just fine.
I use a test 8 on my workbench made with 11.25r and a 60° crossing.
The only adjustment I've ever made on this lokie was to put the wheels on the lead truck in gauge.
I've not tried to find a true minimum radius for this lokie but it will run the 8, at speed, without problems.
Good luck
Many thanks for your help, Skipgear and James.