Custom coupler boxes (draft gearboxes) for Kadees

Some time ago, Ted Doskaris noticed some of the requirements for Kadee couplers on higher stress applications, notably locomotives.

I believe this was coincident on discovering the advantages of center-set couplers and the benefits of better control of the coupler height itself.

He designed and comissioned the manufacture of a coupler box made from aluminum that is similar to the Kadee #911 coupler box (the old 831 type).

This page describes the process Ted went through to design and manufacture an aluminum coupler box, and also and also application notes for the Aristo Dash-9, Aristo RS-3, Aristo Budd RDC, and Aristo E8:


This page describes a comparision between using the Kadee "G" scale couplers and the "#1" scale couplers in his custom draft gearbox:


Ted also released the CAD files to some people who have tried a 3d print of these draft gearboxes, will put some findings here.


Also mounting Kadee draft gearboxes is another whole topic, and instead of carving wood blocks or plastic, several individuals are 3d printing them. I'll report back on my findings and testing.

Many, if not all manufacturers do a lousy job of coupler mounting, either a flimsy post, or wrong height, or no way to put in a secure pad, not to mention almost nothing to allow a "centerset" coupler.

If you look at the "recommended" coupler mount, gear and offset coupler for a USA Trains F unit, you can see what a mess this is.

I'll add a picture, but they use the "large offset" coupler:


If you think about it, pulling on the coupler will twist it downwards. Not only does this cause uncoupling, but it often forces the metal arm down below the railhead and guess what, it catches on a switch and you either stop, derail, or tear the coupler off the mount.

So, with a center set coupler:

Any forces on the coupler only result in it being directly transmitted to the pivot, no up or down forces act on the knuckle.






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