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| Re: Wheel Axels (343598) | |||
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Re: Wheel Axels |
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Posted by tracksionmotor on Sun Nov 26 15:22:23 2006, in response to Re: Wheel Axels, posted by Train Dude on Sun Nov 26 08:57:42 2006. TD: Fulton Frank is semi-correct IF he is thinking along the lines of part -time 4WD where both wheels are locked through a transfer case with vehicle driving on dry pavement...the inside wheel turns faster than outside wheel causing excessive tire wear and strain on transfer case....but we're talking trainzzzzz!Basic trainset truck has a solid axle with a fixed gear ratio to tractionmotor which never changes (I'm answering Frank) that offers ultimate reliability. Consider weight and kinetic energy required to move a trainset from a standing start....all of the stress would be placed upon the differential gears which would fail. Far simpler to accept some additional wheel wear...subways don't run high speeds, long distances and most track surfaces have wear to the point of being 'polished.' The one exception is the Bombardier R-142s. The design of the truck is supported above the axles with hard rubber chevrons that allow the axles to 'twist' following a curve hence 'steerable trucks.' On normal railroad trackage, this is an excellent mechanical situation...the wheels still don't spin at different rates BUT results in a smoother ride avoiding flange contact with rail. Problem was that NYCTA has extensive curves and automatic brake adjusters of Tread Brake Units attempted to compensate for what was worn brakes on outside wheels resulting in burned brakes and more. 'TBU-A Program' changed out over 7000 brake units sucessfully. I show my guys wheels and traxxx. The surface profile of a track is a curve. Wheel profile is such that the trainset settles in between the track...the flange never touches the rail and it is there as a safety device. I use a flashlight and a piece of paper to show normal contact between wheel and track is 1/10th of an inch or so. Sorry TD for using your posting for reflection. IF I could only post..........but I cannot....and I'm sure you know why by now! RRCI Peter |
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