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Recently, I've been contemplating upgrading my scale locomotives and rolling stock to Kadee couplers, as opposed to the standard "lobster claw" couplers. However, I'm uncertain whether the converted equipment would be capable of navigating the tight radius curves after the conversion. The widest curve I have is O-48, and the tightest is O-36.

Kyle Paul

A Fellow "Train-Nerd"

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Hey Kyle......I've swapped out some of my old "drop-link" couplers on my Swiss Buco tinplate freight cars, and on a couple of loco's as well, and I run them on O-30 curves with no problems what-so-ever.

Just make sure you install them to the correct height, (use the Kadee height gauge) and allow for end of car clearance on curves,, and you will be fine.

Peter....Buco Australia.

It is very  dependent on the length of the rolling stock, and the placement of the trucks on the rolling stock.   40 ft freight cars with the trucks near the end should work OK.    Longer cars and cars with the truck closer to the center of the car become more of a  problem.   as mentioned in the other thread, the swing on the coupler in the box is the limit.    As the end/center of the car wings farther toward the outside of the curve, the coupler has to swing the other way to stay coupled.  

Test a couple cars and see what  you think.     You can always mount the couplers without boxes which is described in the other thread and also in the instructions that come with the couplers (or it used to be).  

Couplers mounted without a box were sort of like what was used on street railways - streetcars/freight motors etc.

@Kyle Pax Express

Kyle, I shot the two videos below back in 2016 to show how Kadees worked on O-42 MTH RealTrax curves.  I use the more modern 740-series Kadees, so I'm not sure if that matters versus the 805's.  These cars have the standard-length Kadee coupler shanks with no modifications to the boxes to allow greater coupler swing.  The first video shows a forward move, with coupler slack stretched out...and the 2nd video shows a reverse move, with no coupler slack.

As mentioned above, I believe car length certainly matters.  The boxcars in the video are 40-footers.  Note: the last boxcar (coupled to the caboose) is a "transition" car with a Kadee on one end and the traditional claw coupler on the other end.

As you'll see, the Kadee cars come close but never actually touch corners in the reverse move.  So, if 40' boxcars run without issue on 42" diameter track, I'm guessing your O-48 track should work, too!

Forward Move...

Reverse Move...

Last edited by CNJ #1601

In my experience and as Joe's videos show, 40 foot cars with body-mounted Kadees are fine on O42 in forward, provided there are no reverse curves.

In reverse, the boxcar inner corners on the ends will touch occasionally, but should make it around the curves.

50 ft cars will make it around accurately laid O42s in forward only.

Of course, truck mounted couplers will do better, but I never liked the way they looked.

In general, IMO one of the main advantages of Kadees (besides improving operation) is reducing the coupling distance between cars for better appearance. But this, by definition, means a wider minimum radius is required.


Last edited by Jim Policastro

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