O Scale

[Anonymous]

What is the difference between O27 o72 etc. ?

[IRONROOSTER]

Lionel has two sizes of rails O27 and O72 (sometimes called O31). The O27 is the smaller rail and is also used in their O42. O72 is used in O31 and O54. The number is the diameter of the curves (not the radius like scale). Generally, O27 equipment is not 1/4" the cars/engines are shorter in length, width, and height than scale, but not proportionately so. Industrial Rail makes 1/55 size cars and engines with Lionel size wheels and couplers for use with O27 but this not an exact match. O27 equipment will work with O72 track but not always the other way around since 27" diameter curves may be too tight. As far as I know there is no problem other than appearance in running the equipment together. Some of the O72 Lionel locos require the 72" diameter track.
Enjoy
Paul

[Anonymous]

what about 054 045 063 036?

[BR60103]

Wedge, these still refer to track diameters.
And I think Lionel measures the diameter over the outside of the ties, not to the centerline of the track. At least they used to.
All the 3-rail O gauge equipment is should be compatible for running, except for the problems with too tight curves. On the other hand, mixing the different standards of track often calls for ingenuity.