@coach joe posted:Mel, thanks for the reply. I sometimes see a slow down on my tight 0-31, 0-27 curves that I attribute to friction and inertia. Knowing you're a conventional operator I was thinking that was the cause of the change in tempo of the chuff although a visual change in speed wasn't noticeable.
A while ago, I posted this explanation of why traction tire-equipped locos slow down more the tighter the curve:
https://ogrforum.ogaugerr.com/...9#165010489557025999
This is also true for locos with no traction tires since wheel slippage must still occur in curves, even if some of it occurs on the outside wheel. The reason slowing is less pronounced in locos without traction tires is that the rail to wheel coefficient of friction is lower when no traction tire is present.
Another factor that comes into play is rail profile. FasTrack curves have flatter railheads vs. tubular track curves resulting in greater frictional load on FasTrack curves vs. tubular track curves of the same radius.
