Re: Couplers


How long of a train is required to display this? I am building a layout of the DSP&P and 2 to 6 car trains are the norm. Do I need to consider this?

Allen Farnsworth

On Oct 12, 2018, at 1:06 PM, John Stutz via Groups.Io <> wrote:


This would work for short trains, but merely moves the bouncing section forward on long trains. The problem occurs where the drag of the trailing load overcomes the preload on the coupler springs, causing them to compress and allow the coupler to pull slightly out of the box. Thus the part of the train where drag slightly exceeds preload will expand and contract under varying drag. Aft of this section the coupler springs are fully extended. Ahead of it the coupler springs are fully compressed. The problem area moves up and down the train as the trailing load varies with grade and curve resistance.

This behavior is intrinsic to any coupler arrangement that allows the coupler to move in and out of its draft gear. Kadee's original couplers, still used in their logging cars, suffered from similar problems. MicroTrains' re-engineered "N-scale" split couplers shift the behavior, so it occurs while pushing rather than pulling. NMRA experiments conducted circa 1960 demonstrated that reliable operation of long model trains required that couplers be pivoted on fixed centers, that prevent longitudinal motion.

John Stutz

On 10/12/2018 06:55 AM, Mark Kasprowicz wrote:
Do I recall Jim Vail once submitting a solution to Kadee bounce by fitting two springs instead of one? Not sure how he did it but perhaps it was one spring inside the other, as they tend to do when in the packaging>
Mark K

Join to automatically receive all group messages.