Model Train Couplers: What’s the Difference?

Model Train Couplers: What’s the Difference?

There are a variety of different couplers available for model trains. Most older styles are not very realistic and have some serious flaws, but are still used by many because of their longevity and the tradition surrounding them. Today, though, there are a variety of more realistic or prototypical couplers available in almost all scales that give a more prototypical look and function much as real couplers should. So, model train couplers… what’s the difference?

North American styles

North American-style couplers on prototypical trains are called knuckle couplers or Janney couplers (named after the man that invented them, Eli Janney). There are a few different varieties of knuckle couplers, all with specific functions, but each one works with any others.

Knuckle couplerDetail from a photo by the author
6006337950_1528808a6c_o Detail from a photo by Jay T. Thomson

For years, decades really, the model train industry did not use anything that looked much like the actual thing. Each different scale had its own style, too, as there was no industry-wide, scale-crossing standard. HO scale trains used the horn-hook (also called the horn and hook or horn hook) coupler as the manufacturing standard until the early 1990s.

horn hook couplerA horn-hook coupler on an old Tyco train car, photo by author

There is a myth that the horn-hook was adopted by the National Model Railroad Association as the standard, but this is not true. Various manufacturers referred to it as the “NMRA coupler” in an attempt to legitimize the standards.

The horn-hook was not the only early HO scale coupler, though. The hook and loop coupler, still popular today with G-scale LGB trains, was used on almost all scales, including HO until the early 1960s when it was replaced by the horn-hook.

HO hook and loop coupler, photographer unknown

The Kadee company began producing a near-scale knuckle coupler in the early 1960s, but they kept the patent to themselves and would not share it with other manufacturers or the NMRA. When the patent finally expired, the McHenry company began producing a variation of the HO scale knuckle coupler and then Bachmann introduced their E-Z Mate coupler. A couple other companies also now manufacture scale knuckle couplers and almost all model train cars or engines come with some brand of knuckle coupler as standard. In fact, the NMRA now does have a hobby-wide standard in the Kadee #5 (and variants).

20160604_184456Photo of unopened pack of early 1970s-era Kadee #5 couplers from the author’s collection, photo by author

Many HO modelers prefer the Kadee couplers to all others, all Kadee couplers are metal while the McHenry and E-Z Mate couplers are plastic. All are compatible, however, and I’ve heard many model railroaders say they’ll use whatever coupler comes on the piece of equipment until it fails, then replace it with a Kadee coupler.

20160604_184419Bachmann E-Z Mate II coupler mounted on a hopper, photo by author

N scale has its own interesting coupler history. Like HO, for much of N-scale’s early history, the hook and loop was the standard. By the early 1960s, though, the Arnold company had created what would become the new standard in the Rapido coupler. The Rapido would remain the standard for about the next 30 years.

Rapido coupler, source: Amazon

Today, the N scale standard is the Magne-Matic coupler by Micro-Trains, which in form and design is exactly the same as the Kadee coupler (Micro-Trains and Kadee were both spun out of the same original Kadee Co. in the 1990s). Though it had been around since the 1960s, like its HO scale counterpart, it wasn’t until the patent expired that it become an industry wide standard.

There are a few other N scale knuckle couplers available, including a rigid, non-automatic uncoupling style from Con-Cor. All knuckle couplers for N scale are compatible and visually similar, but for the Con-Cor style, manual uncoupling is required.

Like HO and N, O scale and G scale also early on used the hook and loop style of coupler, and the hook and loop remains the manufacturing standard on G scale trains (though many now come supplied with knuckle couplers for conversion). You can also get G scale knuckle couplers from Kadee, Bachmann, and others. O scale is a little different as there are two types of O scale that are only compatible with some work – two rail and three rail. They each use slightly different styles of couplers, but the Kadee or Kadee-style is becoming the most popular for each.

European styles

European model train couplers are as diverse as their prototypes, and like their North American counterparts, for much of the history of the hobby, they did not resemble the prototypes in any but the most vague of way.

One of many different types of couplers for European prototypes

Early on in European HO or OO scale modeling, the two primary and competing couplers were the Maerklin loop and the Fleischmann claw couplers. Both companies advanced through a series of minor modifications for a few decades until the late 90s/early 00s when Maerklin replaced their loop with the new “close” coupler, which allowed train cars – or wagons as they are commonly called in Europe – to be coupled much closer together, creating a much more realistic looking train.

Fleischmann eventually introduced its own new model called the Fleischmann Profi. Still incompatible with the Maerklin couplers, the Profi offered the advantage of being more durable and tough than any previous type of coupler for model trains in Europe.

Fleischmann Profi couplers coupled together, source: eBay

Another common and popular type of European model train coupler is the Roco Universal coupler, which will mate with a few other types of couplers. I’ve read a few European modeling blogs that indicate the Roco Universal seems to be a favorite.

22610Roco Universal coupler, Source: Roco (linked)


There are or have been a lot of different type of model train couplers, in both Europe and North America. Standards change as years pass, and popularities grow and wane. In the end, it’s up to you, the modeler, to determine what you like best. Have you been modeling for years in HO and still use horn-hook couplers? So have a lot of others, so you are not alone. If you have hundreds of pieces of equipment, it can be expensive to convert them all. It all depends on your personal preferences and what makes you happy as a modeler. If making sure you stick to NMRA standards is what you want, then do it.


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Robert Thomson

Robert W. Thomson is a life-long railfan, the son of a former L&N Railroad B&B gang foreman, and an amateur photographer. He was born and raised in southeast Tennessee but now lives in Butte, Montana with his wife, Connie and cat, Charlie. Robert has worked as a park ranger, underground mine tour guide, freelance roleplaying game writer, and ran his own roleplaying game publishing company until selling it in 2012.

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