Trainman2001 posted:I've held all the grades on the RR to less than 3%. Even with that, I've got problems with tender couplers on two of my 3rd Rail big Pennsy engines uncoupling with the passenger train in tow as it crests the grade. My MTH diesels have no such problem and I frankly haven't worked on a solution yet. My grades are truly shallow and the couplers should work.
The problem you are describing isn't due to the grade per se, but rather the transition between grades. The transition has to be gradual or it will cause constant headaches.
