Originally posted by guitarplayer673
I've read about this and I think I get it. Basically, when B&M made Oblivion their wheel set up was such that there had to be a small gap between the track and the upstop wheels when the train was sitting on level track. The drop on Oblivion is sloped at 87 degrees so that the upstop wheels stay on the track the whole way down. If the drop was exactly vertical, the train would go into true freefall, allowing the train to rattle between the main and upstop wheels on the way down.
By the time they built Sheikra, they had designed spring loaded wheel systems so that the main and upstop wheels could both stay in contact with the track the whole way down a 90 degree drop, without the train rattling back and forth.
Hope that makes sense, I know it's not a perfect description.
Do you please have a source for this, because honestly, this is one of the most ridiculous things I've ever read.