Size matters

Usually, manufacturer literature (catalogs & web sites) specifies minimum curve requirements in the product description. Your best bet when considering a locomotive purchase, or the purchase of large, scale cars is to research using the online catalogs and product finders. This forum is also an excellent resource, as there is usually someone here who owns and can report on almost any locomotive or piece of rolling stock.

Andy

I can only add that I have never bought a loco without first knowning the minimum redius.

Let me add to Michael's comment that it is also important to know the minimum radius of some cars as well. For example, the Atlas Gundersons require an O-54 radius and many scale passenger cars require an O-72 radius.

In addition, there are many folks who even though an engine or passenger car might run on their curves stay away from certain size equipment because they don't like the look of the overhang as it goes around a curve.

Jim

Beyond all this, there is a purely esthetic element you have to decide for yourself. I built the "big loop" on my layout with 72" and 84" curves only, just so I could run anything in O. But, while I can run them, big scale articulated locos stick their boiler front out too far over the outside rail, and some big diesels (the Lionel DD35) with eight wheel trucks have them jutting out so far on even 72" curves, that it LOOKs unnatural to me and I don't like the look. I prefer to run slightly smaller scale locos (scale Hudsons like the williams or the vision hudson and the Lionel scale Atlantic do look good even on 72" and 60" curves).

On the other hand I have met folks that don't mind that at all and run these big locos all the time on 72" curves - even 60" when they will fit and run.