Re: Wheel Howl (not squeal)
Author: mook
Date: 01-03-2014 - 19:47
BART is not alone with wheel howl. SacRT has it too, mostly but not entirely with the newer cars. Supposedly the newer cars have a different wheel profile (perhaps cylindrical?) than the older ones. The older (Siemens) cars have a steady ride, and only howl on a couple of tangent or near-tangent sections of newer construction (concrete ties, if that has anything to do with it) where trains mostly run 45-55 mph. The newer CAF cars are very uncomfortable with their hunting and banging around on the track - I'm surprised that there haven't been derailments with them at a couple of kinky crossovers. They also howl more than the old ones. Very different-looking trucks, so I suspect car and suspension design as well as the wheels (the newer ones can get into a severe bouncing action at 54-55 or more on some track (they can usually get up to about 57 before the overspeed trip happens). My other observation is the track - howl and severe ride problems occur mainly on higher-speed sections of newer track with concrete ties. Howl just doesn't happen in wood-tie sections, period, and the ride tends to be a little calmer there too. The data are showing how that happes are problem in the TCRP report - will have to look that up and see if the local transit folk can be talked into a few adjustments.