Paul,
Thanks for your reply.  You are the first person that has made any sense to us.  You cleared it up for us. 

I have a G scale train,(Blue Comet) older model, 45 mm between the rails, the layout is 100 feet long.  There is a turning radius at both ends that is 52 inches across and 6 feet 6 inches long, which forms a circle and then there's a double track running down to the circle on the other end.  But I've been thinking about a 3 truck Spectrum Shay by Bachmann.  Would it run on this track with a 52 inch curve across.  Obviously, we don't know much about this.  Is there any reason why this Shay mentioned above wouldn't run on this track?  We've heard from people that don't know any more than we do about it that it may not make the turns at the ends of the runs.  Help!

Will a "Spectrum G Scale Narrow Three-truck Shay" run on our 45 mm G scale track?