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| Re: Wheel Axles (343979) | |||
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Re: Wheel Axles |
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Posted by Jace on Mon Nov 27 10:52:31 2006, in response to Wheel Axels, posted by Fulton Frank on Sun Nov 26 08:12:36 2006. Low floor trams/light rail cars have either axle-less trucks or drop (crank) axles between independent wheelsets. These are some complicated units especially for full low floor vehicles where you have powered axle-less wheelsets. The reason these designs developed and are used is that you get a low boarding height and no interior steps to contend with - a big plus for street operations, but even here the complexity of the wheel set design has made full low floor cars a lot less popular compared to partial low floor cars (cars with standard motor trucks on the ends and only unpowered independent axles in the middle). Aside from this specialized application, there really is no need for single axle wheels - they're a lot of added complexity, cost and maintenance with no real benefit.The real way to deal with flange wear (and hence noise) is by matching the profile of the wheel to the profile of the railhead. Included in this (ideally) is the design of the spirals (entry to curves) and the superelevation of curves. Subways have a harder time playing with the curves than any other railroad since they're pretty much fixed by the tunnel or el, but they do work on the wheels and the rail. The wheelsets are kept at a specific profile by regular visits to the wheel truing machine. The railhead is kept in shape by rail grinding. Freight railroads in the US don't re-profile freight car wheels (they use only one wear wheels) but they are very aggressive in rail grinding. Subways typically watch the wheels more so than the railheads but there is some rail grinding done - Speno or LORAM has a small grinder they rent out to subways and NYCT has had rail grinders in the past (don't they have a new one on order?). |
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