I have a question,, there are 3 different geared wheelset replacements made for the old Weaver chaindrive units. I have a 3 rail FA that I need to fix. The 3 choices are 40/115 (scale), 40/145 (semi-scale),and 40/172 (HI Rail) My Question is what were the factory size that came with the engine? For the 3-rail was it the 145 or the 172? I would assume the 172 but want to make sure.
Replies sorted oldest to newest
The number refers to the tread width, in inches (.115, .145 and .172", respectively).
I would choose .172 for 3 rail. While they're all useable for 2 rail use, the .115 is very fine scale and likely won't stay on 3 rail track. The .145 is a fairly standard 2 rail wheel that may stay on the track, thus the .172 is most likely the one you want. Measure your existing wheels.
Thanks, that is what I was thinking
I agree with Boilermaker, you definitely want .172 tread. However, the other important consideration is flange depth. Make sure the seller understands that you want a "3-rail" or "Hi-Rail" wheelset. The original Weaver 3-rail wheels were about .800 diameter (which is a little undersized for a diesel.) I always wondered whether those wheels had been turned down in a lathe to make the flanges deeper, and thus suitable for use on 3-rail switches and track.
It was pretty common back in the day to have wheels with .172 tread, and a small NMRA flange suitable for 2-rail track. My understanding is that most of the 2-rail stuff today has .145 tread which is a good compromise between appearance and operating reliability.
I'm sure you already thought of this, but you might find a busted-up 3-rail example on the 'Bay, and cannibalize the wheelsets.
Access to this requires an OGR Forum Supporting Membership
