MTH 4 Truck Shay Minimum Curves

Couple of notes about shays- I have BOTH Lionel and MTH variants, 3 and 4 truck shays.

Shays, both the real ones, and the model tend to have an asymmetrical turning radius because the driveshaft is down one side and must telescope or collapse in length. In other words, if you run with driveshaft on the outside of the curve, you have one minimum, and when you run driveshaft on the inside of the curve you have different minimum curve.

This is why you are going to see different answers and different minimums. I have run a Lionel 3 truck shay on Fastrack 048 curves as an example, but the driveshafts had to be to the outside- AKA engine only runs the loop facing a certain direction.

The manufacturers often list the highest value minimum curve because if your layout is not a pure oval loop with curves in both directions, then the higher value minimum becomes the new minimum.

Again, to be clear- switches- other than the radius or diameter of the curve section, have nothing to do with will a shay run. An 072 rated shay is rated that way so it can run both directions, driveshaft to the inside, driveshaft to the outside.

It very likely will do a simple loop of 060, but might be restricted or work best in one direction only. As you get to smaller and smaller diameter curves, the more the driveshaft and what side it works on (collapsed length minimum VS telescope length maximum).

Also, previously discussed here with pictures and other examples. Also multiple links to other topics in the replies.

https://ogrforum.com/...9#172752760221811799

Vernon thanks for all your help with this.  It makes a lot of sense that the side the drive rod is on will effect how tight of a turn it will take.