Re: Kadee Scale Coupler Operational Reliablity

soolinehistory <destorzek@...>

--- In STMFC@..., "Aley, Jeff A" <Jeff.A.Aley@...> wrote:


I believe that the kingpin-to-kingpin distance is also critical, and this is where the curvature really comes into play. The two kingpins are points on an arc of a circle (assuming constant radius), and the more degrees of arc they encompass, the worse the problem will become (imagine a car and track such that the kingpins extend over 180 degrees of arc!)
Thus, I believe it's a combination of the kingpin - to -kingpin distance, as well as the kingpin to striker distance, as well as the curve radius that causes our problems.


I can't say I disagree, although I usually point out the end overhang difference, as once pointed out, it becomes readily apparent where the problem lies. However, cars or locos with a large distance between the coupler and striker also tend to have long truck centers, and the additional angular displacement just exacerbates the problem.

Before anyone thinks I'm picking on modern diesels, the same problem exists when mixing long passenger cars with freight cars, and when trying to use the pilot coupler of a steam loco for switching. Model steam locos are a partial curse; the tender often has coupler geometry most like that of a freight car, but since the locomotive tends to pivot about the center of it's rigid driver wheelbase (few model locomotives have fully functional pilot trucks that actually guide the loco into curves) the pilot couler tends to be a long way off the track centerline when in a curve.


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