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To: Gauguin who wrote (51772)	6/4/2000 2:47:00 PM
From: Ish	Respond to of 71178

<<Greater speed may decrease or increase area. >> Decrease. Less down force. <<Greater drive load on powered wheels may have more.>> Yep. Surface distortion, in theory.

To: Gauguin who wrote (51772)	6/4/2000 4:39:00 PM
From: Jacques Chitte	Respond to of 71178

A couple of stray thoughts to shovel into your boiler. 1) Hardening the wheels increases their capacity as springs - how much pressure they can take before deforming. Going inelastic. Mild steel tends to squuush under a ball-peen blow. It makes a dull thunk and takes a dent. But hardened steel rings like a bell and bounces back elastically. Also - the extremely high pitch with which the steel rings (surely you've struck steel objects with a hammer to get those marvelous steely bat-shriek ka-tinng! sounds?) contains a clue. And that is, the speed at which trains roll is so much slower than the elastic limit of steel (which reduces basically to the speed of sound in steel, and taht is two miles a second or so!) that the "at rest" case and the "moving at 80 mph" case should be treatable equally. The one thing is that I don't think a round wheel tends to roundness. If a surface defect appears in a rail wheel, it won't tend to "heal" shut, but instead worsen. It's the foundry's job to get the wheel as round and annealed as possible, so that there may be a long rolling life before dings, rock marks, premeditated coinings, moose oopsies etc. wear a wheel enough out of round that it is no longer "good". If wheels were cylinders and rails flat, the contact patch would be a rectangle. But wheels are conical and not mirror-bright, and rails are crowned in a sort of pound-cake or overfull-beer curve. This will conspire to give the contact patch more of an irregular cigar hsape. But will it shrink it, relative to the simple cylinder-on-plane example? Some but not a whole lot, is my guess.