this is the usual pic of the engine I see (above) or think of.
I noticed just how big the pilot wheels appear compared to our models. The pic below caught my attention.
I was given some advice when converting my Allegheny over to 2 rail. "The pilot wheels should be smaller" or I'll create a short. Sure enough I had to swap them out right away when I noticed severe sparking rounding the first curve I ran her on. It was a quick solution that I did not look into any closer. It solved it and I was happy.
So I can't help but wonder if again, our models are modified just to make life easier? Real dimensions and the way the real weight is handled is probably much different than our toy models that have a different set of problems to solve. Probably why I read of so many shelf queen engines being produced over the years?
Being a modern diesel fan has helped me avoid some of the basic steam engine problems, and solutions over the years. I ran HO when I was a kid and had poor results with steam vs. diesels running reliably. As my guests prefer steam era engines, I'm forced to look closer and study these goliaths.
Blast away now! 
I'm way behind.
Thanks for the topic and all the info provided. Now I have to go back and study everything closer.
