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| Re: R Train May Run 8 Cars Instead of 10...Re: Is There an Update on the R160's Wheel Wear Problem? (1640023) | |||
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Re: R Train May Run 8 Cars Instead of 10...Re: Is There an Update on the R160's Wheel Wear Problem? |
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Posted by Stephen Bauman on Fri Mar 14 20:36:56 2025, in response to Re: R Train May Run 8 Cars Instead of 10...Re: Is There an Update on the R160's Wheel Wear Problem?, posted by Train Dude on Fri Mar 14 09:17:31 2025. When testing braking on railcars, procedures call for testing in AW0 and AW3 load conditions which calls for loading weights onto cars to simulate heavy load conditions.I wonder whether a test at two loading weights is sufficient from a purely engineering perspective. The railcar contains an energy storage component - the suspension springs. This means there are resonance frequencies that may be loading weight dependent. There are damping components that make resonance oscillations imperceptible to the passenger. However, these damped oscillations may have a subtle effect on the wheel-rail interface and on braking. I can think of an analogous situation back when I participated in organized endurance bicycling events. I was traveling fast on a blue stone road. The road wasn't smooth like asphalt but it wasn't bumpy like cobblestones. I applied my brakes and did not experience an instant speed reduction. The reason nothing happened was because both wheels were slightly off the pavement due to the roadway surface and my high pressure tires. Without the road contact, the pressure exerted by the brake pads was sufficient to lock the wheels. Had I held on to the brakes both wheels would have skidded, when the bike returned to the ground. The solution was to let go of the brakes, so that they could roll in the 1/4 second it took the wheels to regain contact with the road. I can conceive of something similar with a railcar. The wheels don't have lift off the rails. The car body's weight might be reduced on the truck, as a result of damped oscillation. The applied brake pressure for a given brake handle position is determined statically, before the train starts moving. It isn't reset, while the train is moving. While this pressure would not have locked the wheels in normal circumstances, it might if the effective load on the truck were reduced during a damped oscillation. This effect might not be noticed but would put successive flat spots on the wheels. This could be interpreted as excessive wear. This is just a potential solution in search for an appropriate problem. Still this potential cause should be considered among the usual suspects. |
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