About a month ago Union Pacific dumped five covered grain hoppers south of Pontiac,IL. Still laying out there if anybody is interested. The cause was blamed on harmonic rocking. I thought harmonic rocking was caused by joined rail, the staggered rails and all. This track was rebuilt with welded rail for 110 mph Amtraks with state money a few years ago. Never got the 110 mph trains but, you would think a local could stay on the tracks.
Most often associated with jointed rail. But not 100% confined to that. If as you described, with that upgrade, sounds like nobody is seriously maintaining the line? Boxcab E50
On CSX, we have restrictions through certain curves for certain cubic foot capacity covered hoppers. You must try to avoid the speed range between 14 and 21 MPH, where most of the harmonic rock is generated.
Bill, harmonic rocking is not limited to just jointed rail. Continuous Welded Rail is also prone to allowing freight cars to rock due to bad crossties and the lack of roadbed and subroadbed maintenance. A good tamping and some extra ballast would fix this problem in most cases.
I believe it's just one of those things. A combination of high center of gravity and car design. One of those things that just happens. Once it starts, it just amplifies. Sorta like why do we lose radio contact with space ships during re-entry?
Bad car design...! Must be a pain to have them in a train.....thanks. (BTW, I can explain loss of contact during re-entry. PM me if you want more info...:tb-wink
Some of this can be adjusted. I can remember changing springs in trucks, or simply swapping complete trucks. Also, we made changes to the side bearings. Boxcab E50
