Magnum XL-200
Like all modern coasters, Magnum is locked onto the track with wheels above, below, and beside the rails. But surprisingly, the wheels below the track (known as the "under-wheels" or "up-stop wheels") were added after Magnum XL-200 opened! Magnum's trains originally had pads under the track, but the cars were quickly modified to change the pads to wheels. Gemini, which also was built by Arrow Dynamics, has pads under the track even to this day.
©2012 by Joel A. Rogers.