BaltACDCurves are the high wear locations for rail.
As illustrated by the squeal heard at Deshler as trains transit the transfers. You just know that the one wheel that's sliding, ever so slightly, is doing damage at the same time.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
tree68As illustrated by the squeal heard at Deshler as trains transit the transfers. You just know that the one wheel that's sliding, ever so slightly, is doing damage at the same time.
That squeal is almost certainly flange contact. Wheeltread noise is like that from creep control, a low ticking or ringing that would be completely lost in the squeal unless you had a good waterfall frequency analyzer.
Here is a good reference that 'started much of the modern understanding' of wheel/rail interaction
Up to the point Wickens started his analysis of four-wheel-vehicle stability, the 'accepted wisdom' was that which produced the C&O Train X and TALGO vehicle "stability" -- the idea that wheels that rotated freely relative to each other produced better riding and guiding than a solid wheelset. I worked out a method for doing axles that would permit differential rotation; in fact, someone smarter than I am went so far as to get a patent on the same general approach with the same design considerations. He could never quite sell anyone on the idea, and now we know considerably more about why it wouldn't work as intended.
Where the slight differential slip DOES come into its own is likely when HAL goes into the wrong excess range for the railhead steel and hardening method. When you are close to the range in which plastic flow under a work-hardened surface and 'all that other jazz' start to be a danger, anything that spot-increases the potential for damage, particularly if it has the 'adhesion' of higher spot weight to make its effect more direct, can put a contact patch 'over the line' into, say, vertical crack formation and propagation, or if it occurs close to the root of the wheeltread coning, gauge-corner cracking. And those are of ominously greater importance than squeal and scuffing wear from inadequate spot greasing...
OvermodThat squeal is almost certainly flange contact. Wheeltread noise is like that from creep control, a low ticking or ringing that would be completely lost in the squeal unless you had a good waterfall frequency analyzer.
I'm pretty sure it's wheel tread vs railhead - the flanges are not a factor. The wheels are self-centering on their treads.
Tune in to the Deshler rail cam (free on YouTube) sometime when a string of loaded coil cars is making the turn south on the southwest transfer. The squeal is constant, the speed is at or under 10 MPH.
If the rails are damp, lighter cars won't squeal at all, or minimally, as the interface is lubricated. Dry rail = squeal.
Corrugation is the result of wheel tread damage. Railhead (ball) wear is increased as the angle of attack of the trucks increases (flange trying to climb over the gage corner)
tree68I'm pretty sure it's wheel tread vs railhead - the flanges are not a factor. The wheels are self-centering on their treads.
Think about this a moment. If the wheels are 'self-centering on their treads' (which in fact, they are) how can one of them be continuously skidding and not the other? Moreover, if the force on the two wheels is approximately equal, which is one of the things a three-piece truck is designed to assure ... where does the force come from that can continuously skid a wheel? You understand from the fact that air brakes work that the force between wheel and rail is great enough to transmit enormous braking effort, from heavy pressure through a large shoe area. Surely you don't think a contact patch on one wheel has the ability to sustain a skid -- a noisy one, so you know energy is being transferred -- on the other end of the axle.
If the rails are damp, the gauge corner and flange are lubricated just as the tread contact patches are.
Never too old to have a happy childhood!
OvermodThink about this a moment. If the wheels are 'self-centering on their treads' (which in fact, they are) how can one of them be continuously skidding and not the other?
On a curve, one wheel will have more weight on it than the other, either as a function of the displaced center of gravity (on a slower speed curve with a cant) or due to centrifugal force. That wheel will govern how fast the set is turning.
Since the path around the curve is a different length for each wheel, one will have to be skidding, although it's possible that both are skidding. Can't deny that.
Either way, at least one wheel is sliding. The only debate is whether it is being turned faster than the rail is passing under it, or slower.
As I said - tune in to the Deshler rail cam and watch a few trains go over the transfer tracks (go to the "360" cam).
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