Sergent Couplers

Testing Sergent Couplers for the Bronx Terminal

all images are clickable for big’uns
Sergent Coupler

HO Scale EN87A Narrow Shank pre-assembled coupler

I have been testing various types of couplers for use on my Bronx Terminal layout, trying to find a good mix of appearance and performance.

The uber tight radiuses on this layout really tax couplers.  Until now I have always used Kadee #5’s or #58’s on all my equipment.  They work very reliably and look ok.  On the tight curves of the terminal the self centreing action of Kadee couplers can be a bit of a hindrance.  In order to couple reliably, some handling has to be done,  I can live with that if I have to.  I figure if I have to handle the couplers anyway, perhaps I should look into some other options.

One alternative is to use truck mounted couplers.  Truck mounted couplers will always be lined up relative to the trackwork.  I am not too concerned about how well this would perform, as long as trucks are free rolling, pivot properly and the cars are weighted properly they work fine.  Most equipment in N scale has truck mounted couplers and the equipment does not suffer from it.  However, replacing all the trucks on the cars would be quite an investment, so I would rather not have to do that.

I decided to take a closer look a Sergent Engineering Couplers, so a couple weeks back I ordered a sample of the two types they offer, EN87A narrow shank, which come pre-assembled in a draft box and some EC87A with compatible shank, also pre-assembled.  The EC87A are a drop in Kadee replacement while the EN87A are designed to be mounted to the car.

Sergent Coupler

HO Scale EC87A Compatible Shank pre-assembled coupler

Sergent Coupler

There is no question that these couplers look great.  They are scale, and noticeably smaller than Kadee couplers. But they are also completely incompatible with Kadee couplers, so its an all or nothing decision to use them.

Sergent Coupler

But geez, look at them.  They look fantastic.

Sergent Coupler

Mounted on a couple of cars they look even better.

Sergent Coupler

The car on the left has a Kadee #58 scale coupler on it, the right, a Sergent Coupler.  A bit finer in detail than the Kadee #58

Sergent Coupler

So we’ve established that the look great, but how well do they work?

They work well.

To uncouple the cars, a magnetic uncoupling wand is used.  On the end of the wand is a small magnet that is simply touched to the top of the coupler releasing the knuckle and opening the coupler.

I forgot to order one of these!

Fortunately I was able to improvise by using a small rare earth magnet attached to the end of an Allen wrench.  While not as functional as the uncoupling wand from Sergent, it works well enough to test the couplers.  The Sergent version also includes a small hook to open a closed coupler should it get closed after uncoupling from another car.

One trouble area I find is that they can occasionally be hard to get to reliably couple.  Seems that a bit more force than normal is required to get the knuckles to stay closed.

I have found that polishing off some of the rust finish with a rotary tool helps quite a bit, but still they can be occasionally hard to close.  Not sure how irritating I would find that.

I have shot a few videos showing them in action.

Watch them in HQ if you have a fast connection, it will look better.

Sergent couplers in action. They couple in a manner similar to the prototype. Only one knuckle has to be opened to couple.

Taking a couple of couplers for a spin. They work well and look great!

From the preliminary tests I have done so far I really like these. Since I only have a fleet of about 35 cars so far changing them all over isn’t a big issue. One concern is whether or not I can successfully mount one on my CNJ 1000 Brass Loco. Mounting a Kadee to this engine was a challenge, not sure if I can change it over or not. That will likely be the deciding factor whether or not I settle on these.

Apparently couplers are a passionate subject. A recent thread about Sergent couplers on the Model Railroader forum was locked as, like always, opinions got the best of people. That said, I would love to hear from modelers who have actually used these in a serious way.


About the Author:

I'm your host, Tim Warris, a product developer in Port Dover, Ontario. Since March of 2007 I have been documenting the construction of the former CNJ Bronx Terminal in HO scale. For my day job, I design track building tools for Fast Tracks, a small company I own and operate. Fast Tracks makes it fast and easy to hand lay your own trackwork. Stop by our website to learn more!

Posted by: Tim | 03-06-2009 | 03:03 PM
Posted in: Latest Posts | Sergent Couplers


  1. Truck-mounted couplers in HO became a no-no in HO, because of the horn-hook couplers, which work by pushing sideways. Backing up would invariably force a truck to derail, so body-mount works much better, as well as looks better. 😉 The Rapido couplers in N don’t have that problem backing up, so I guess truck-mounting never became much of an issue. I have a couple cars that are body-mounted, and they cause problems on my small-radii curves, so it’s kind of backwards in N, I guess…


    Comment by Jongl — March 6, 2009 @ 3:52 pm
  2. Did you buy the pre-assembled couplers, Tim? You might want to consider the kit form next time…the ones I have right now perform flawlessly, and take very little force to close and keep closed. I’ve heard (indeed, they say on the website) that people have had better luck with the kits than the pre-assembled couplers.

    I haven’t had a chance to test them out on an actual layout, but I’m hoping that I’ll get a chance to this evening or this weekend.

    Comment by Robert Beaty — March 6, 2009 @ 4:22 pm
  3. The Sergent couplers do look great, but couldn’t you get the same results by just removing the centering springs on your existing #5/#58 couplers?

    Comment by Joe — March 7, 2009 @ 2:57 am
  4. I’m just happy to see trains finally running in the Bronx!

    Comment by Chris — March 7, 2009 @ 6:16 am
  5. I’ve been thinking about switching to the Sergent couplers also but have the same dilemma – mounting issues. Looking forward to your progress report.

    They sure do look good!

    Comment by Terry — March 7, 2009 @ 10:56 am
  6. I use the Sergent couplers on my small switching layout and love them. I’ve had the same problem with the knuckles not locking at times, but the realistic look and function are too important to give up. Plus, having to open the knuckle and line the couplers into position have slowed the switching process which makes it more realistic and fun.

    Comment by Scott — March 8, 2009 @ 11:50 pm
  7. I’ve been using Sergent couplers for about 4 years now, maybe longer, and they’re down right amazing. As with all couplers, they have an up and a down side. However, the only real down side I can find, is the manual uncoupling, which, to me really is not much of a downside, but may complicate my future layout plans (Cajon Pass).

    Anyways, GREAT videos!

    Comment by Josh Baakko — March 28, 2009 @ 12:59 am
  8. I do prefer the Sergent Engineering couplers for a couple (pun) reasons. First, they look and operate great. More importantly, for me, even the smallest of layouts can demand a two-man crew. I really like the prototype-like realism; they can totally eliminate the need for any sort of fast clock. Thanks for the great videos, and your fine products, too!

    Comment by D.R. Haworth — July 20, 2009 @ 1:51 am
  9. I first began using Sergent couplers roughly five or six years ago. They easily put every other manufacturer’s couplers to shame in terms of prototypical accuracy of appearance and operation. They can at times be a bit finicky in regards to coupling smoothness and sticking of the locking mechanism (mainly on the pre-assembled ones), but the issues are minor and easily overcome with a proper break-in, and the greatly improved realism is worth the occasional fiddle work.

    While I have yet to outfit my entire collection with them, all my motive power and most of my more frequently run rolling stock are fitted with Sergents. They’ve definitely got my support for the long run.

    Comment by Jamison Amis — August 27, 2009 @ 12:02 am
  10. Hi Tim,
    I’ve just started using Sergeant couplers and i think they are great. I have a smallish fleet of New Haven diesels and (so far) about 20 cars and what i have fitted with Sergeants looks great and operate well. The Sergeant uncoupling wand is certainly very useful, i recommend it! I don’t find it a problem having to manually uncouple the cars – it’s simply replicating prototype practice!
    Thanks for the videos and the great website.
    Cheers from England,

    Comment by John Edge — October 6, 2009 @ 10:52 am
  11. Tim I originally bought the Sergent couplers for more detail on my locos and cabooses. But after trying out my first set I was hooked I finally closed the gap on my RS1’s from about 6ft to about 3.5 feet [major improvement]. I’am now equipping everything in my fleet with them,my freight cars have much more detail now because I started putting lift bars and airhoses on everything!. I have one guy in our rr group who constantly puts down the Sergent couplers,says you can’t see the detail in a moving train. I try to explain “If your trying to model realism go all the way” Sergents work much better than KD’s no slack! your rr deserves them.

    Comment by Dale Kritzky — November 26, 2009 @ 8:22 pm
  12. Tim, I’ve also been using the Sergents for a few years, and when I got my latest orders of the new F’s and SF’s, Frank had included a note about a new break in procedure on the website. Just a number 2 pencil and some some sliding the couplers together to remove knuckle flash and they work perfectly. I would guess that they couple with no more pressure than a KD after break in now.

    Comment by Steve Wilbur — December 30, 2009 @ 3:12 pm
  13. The only thing I can say I don’t agree with Tim on is where he says that choosing to go with Sergent couplers is an “all or nothing” decision. Kadee (including the many clones) and Sergent couplers are not compatable… but it is easy enough to make a ‘conversion car’ (or two) with a Sergent coupler on one end and a Kadee coupler on the other end.

    I also want to say that Sergent couplers CAN utilize a centering feature! In S scale, I have successfully built a working prototype using the gear box from a Kadee 808 coupler package… the video for it can be seen at the following link :


    … and photos of the assembly can be seen at the following links :


    I intend to do so, but have not yet tried building one of these in HO scale. But I feel sure it will be just as easy as the S version was, and work just as well!

    Comment by John Degnan — May 16, 2010 @ 4:50 pm
  14. I have successfully managed to get a Sergeant Coupler and a Kadee #58 to lock knuckles to get a train around a layout. Not terribly pretty, but it is doable. Forget doing that with a #5 though. Completely does not work.

    I’m giving serious consideration to doing Sergeants for my future home layout, and thankfully haven’t spent much time doing any work to the fleet as of yet (most is still all in boxes with original wheels and couplers, all of which are likely being changed out for semi-scale wheels and scale couplers).

    For me, the purpose of the layout is operations. I’m not terribly crazy on super-detailing the cars, but I want them to operate as realistically as possible…Which means having the conductor radio the engineer “okay, give ’em a stretch” to ensure the couplers did indeed lock…



    Comment by Jon Calon — November 8, 2010 @ 8:14 pm
  15. I realize this si a two year old blog, but I found it, so maybe others will too.

    Kadee and Sergent are nor directly compatible, you are right, however, just as a Kadee and a Horn Hook CAN be coupled if you open the Serget copupler, back it into the Kadee pusehed all the way to the side fo the car, then push the couplers back to center so that the Sergent knuckle will wrap around the Kadee’s knuckle, you can get it to lock. It will work with McHenrys and the Walthers ProtoMax couplers as well, though some Kdee clone knuckles are simply too thick to fit.

    Comment by Morgan — January 9, 2012 @ 11:58 pm
  16. Hi Tim,
    “One trouble area I find is that they can occasionally be hard to get to reliably couple. Seems that a bit more force than normal is required to get the knuckles to stay closed.”

    I also have this problem with reliable couple even with the ones I have assembled myself. The ball seems to get stuck somehow. I have used a pencil to lubricate the coupler, but they still couple unsatisfactory – Any ideas

    Comment by Damian — December 28, 2012 @ 4:29 pm
  17. I commented above. In addition, and I do not recall where I read it, a custom magnetic wand with a 90 degree bend to the handle can be fabricated such that one can come in from the side to uncouple, as opposed to from the top. I confess to buying the couplers already assembled. To me they are a joy to operate with.

    Comment by Gndboy — April 4, 2013 @ 3:49 am
  18. I’ve been looking at switching to these couplers for a while now and I’ve been trying to figure out, what coupler from Sergent is a close replacement for the kadee #5 because most of my rolling stock and locomotives are equipped with them

    Comment by Keldon — November 11, 2013 @ 5:16 pm

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