Talk:Curve resistance (railroad)

Added WikiProject Physics

I just made this part of the WikiProject Physics since the results of the Russian experiments don't seem to have a physical explanation (yet). Why does decreasing the velocity (below the balancing velocity) result in a more rapid rise in curve resistance than an increase in velocity? The unbalanced sideways centrifugal force is proportional to v^2 so one expects a much more rapid rise in curve resistance with increasing v than with decreasing v. But just the opposite is observed and the Russian results seem to have been unknown in the USA until I wrote this article so it's unlikely that anyone in the US has tried to analyze it. Perhaps it's due to there being more time for the wheel sets to slide downward due to gravity when due to slow speed they have more time to slip downward (towards the inside of the curve. And the creep forces are not linear and might max. out at low velocity since the % creep becomes high at low velocity (creep is deltaV/V). A major factor in all this is likely hunting. David S. Lawyer 01:06, 11 December 2013 (UTC) — Preceding unsigned comment added by Dlawyer (talk • contribs)

Rename "Erroneous formulas"

This term should be removed, for two reasons: (a) it is WP:NOR - the standard railway literature on resistance does not (or rarely) call these formulas erroneous. (b) Formulas are always valid in a context: For example, E_pot=mgh is valid or "correct" or "good enough" when h is small, but not when a body is significantly removed from the earth. This does not make E_pot=mgh "erroneous". Especially in engineering contexts, there are lots of estimation formulas that are not derived from first principles but based on experimental measurements, for example, all formulas for (air) drag. These formulas are not "erroneous", but simply approxmations. All the /R formulas are the same - and they are good enough, otherwise they would long have been replaced with other ones. There is no reason that WP should second-guess the authorities in this specific area. --haraldmmueller 16:13, 20 June 2015 (UTC) — Preceding unsigned comment added by Haraldmmueller (talk • contribs)

I agree that "erroneous" is a confusing description; "Approximate formulas" would be a better title. Reify-tech (talk) 16:44, 20 June 2015 (UTC)

I have rewritten the article so that it follows established standard engineering practice. The "Russian experiments" are still there, but they now follow the textbook formulas. --haraldmmueller 20:01, 6 August 2015 (UTC) — Preceding unsigned comment added by Haraldmmueller (talk • contribs)

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