N scale Spectrum 2-8-0 binds - downhill only

[kcs114]

I have a first generation Spectrum N scale 2-8-0 that runs like a Swiss watch on the level and uphill. But going downhill with ten cars and a caboose behind it, it has a very jerky motion that must be a bind because it is in sync with each revolution of the wheels. When I put it on Bachrus rollers or upside down in a cradle, there is no bind. I checked the clearances in the rods and valve gear, and they appear to be OK. The fact that this only happens when going downhill, especially on my steeper (3.85%) grades has me stumped.

[hminky]

I have a first generation Spectrum N scale 2-8-0 that runs like a Swiss watch on the level and uphill. But going downhill with ten cars and a caboose behind it, it has a very jerky motion that must be a bind because it is in sync with each revolution of the wheels. When I put it on Bachrus rollers or upside down in a cradle, there is no bind. I checked the clearances in the rods and valve gear, and they appear to be OK. The fact that this only happens when going downhill, especially on my steeper (3.85%) grades has me stumped.

Yeah, that is what worm geared steam locomotives do going downhill.

Always have always will.

Harold