different model joining

One thing to keep in mind is that older trains will not work on Revolution's inclines, and Revolution trains will not work on the steeper older inclines, at least not without some weight. But even with weight added, Revolution engines may have troubles coming from the drastically different traction tires.
I don't know if this is everyone's problem, but since the very beginning I've found it annoying that even after filing down the activation tab, Revolution engines will get suck on the curved TOMY slopes. the ends of them have very short flat parts, and my Trackmaster Ryan always gets its drive wheels lifted off of the tracks by it.