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How to Fix Kato Couplers

I’m an N scale model railroader. Like some of you, I run mostly Kato brand locomotives and numerous other brands of cars such as Atlas, Micro-Trains and Athern. It is fairly well known that the installed Kato couplers simply don’t play well with others; specifically Micro-Train couplers and McHenry couplers which dominate the couplers installed on most non-Kato rolling stock.

Some people have a dedicated conversion car with a Kato coupler at one end and a Micro-Trains coupler at the other. This car stays between the locomotive’s Kato coupler and all the other rolling stock. I didn’t feel this was an ideal solution for me as I do a lot of operations and didn’t want the extra length of a tag-along.

The typical fix is to replace the couplers. This conversion costs $5-15. You’ll need to drill and tap holes in the shell and perform minor cutting and filing of the locomotive shell to allow the new coupler to fit. Ultimately this is the best solution.

The other evening I was running my newest Kato locomotive, a sweet SD45. The special order conversion couplers hadn’t yet arrived and I just couldn’t help myself, deciding to take it out on an operations run. Naturally, it had a most difficult time connecting to my cars. I began to wonder what’s the hang-up. Kato makes great stuff and clearly put a lot of effort into their coupler. Could it be adjusted to work with other couplers, I wondered?

model train coupler diagram

I started examining the shape. Kato’s coupler is unusually small, rather bluntly shaped, and had a small stop tab on the left outer side of the knuckle. As I watched a Micro-Trains (M-T) coupler try to engage, the M-T’s lip shank would strike the protrusion on the Kato knuckle shank, preventing the coupler hooks from getting close enough to couple.

So I nipped off the stop tab on the Kato coupler. Better, but still no connection.

The next issue was the small opening of the Kato knuckle itself, being both small and shaped flat rather than angled. This opening was about the size of the entire M-T knuckle and without alteration required quite a bit of force to get the M-T knuckle into the Kato knuckle.

I used a small triangular jeweler’s file and removed the sharp inside corners on both the knuckle and lip shanks, being very careful not to file off the amazingly small hooking lip at the end of the knuckle hook.

Bingo! Without the human hand the loco connected with the car and coupled on the first try with gentle pressure. I ran my operating session setting out and picking up about 20 cars and the couplers worked pretty well. Sometimes the almighty hand was needed to get a positive connection (the knuckle jaw opening could be larger still) but it was a simple 5 minute adjustment without disassembling the locomotive.

It should be noted that making these modifications will likely make coupling to another Kato coupler difficult. And a set of Micro-Trains couplers properly installed on your loco would still have an edge in coupling with the least trouble, but the modified Kato couplers were now functional and are perhaps good enough for the needs of most model railroad enthusiasts.