Model Railroading > Problem with long HO freight consist uncoipling

The consist is uncoupling at about 7 cars behing the engine.  The cars are new and in good shape, so I don't think it is a coupler problem.



Edited 1 time(s). Last edit at 02/24/26 07:29 by Floridarailfan.

Check coupler height, vertical flexibility, TYPE (plastic vs. Kadee).  It it is the same coupler, inspect the knuckle to insure the small hook at the end is in good shape.  Check the condition of the knuckle springs, making sure the coupler has no binds that allow it to stay open if the slack runs in.  My policy is to eliminate all plastic couplers before a car or locomotive enters service.  Plastic couplers can look OK, but are fragile and prone to excessive vertical flex and malfunction.  Over the years, older kadees can develop a small amount of corrosion in the knuckle joint.  A tiny amount of lube has brought many recalcitrant couplers back in line.  If the train breaks-in-two at the same spot, look for a dip or hump in the track.



Edited 1 time(s). Last edit at 02/24/26 08:29 by g-spotter1.

1 Make sure you use a coupler height guage
2 I use KD #5's on all rolling stock
3 Lately I have noticed the KD (copper flat) spring is not loose and not returnining coupler to center.
4 Do a coupler inspection as the train is rolling out of the yard and as the train is enroute and watch for  cars dipping at the same place
5 Make sure the KD trip pins are clearing the rail tops
 Feel free to add to this,  

Ed Stewart
Jacksonville, FL

Coupler height is critical and should be close as possible to the correct height. I really like using Micro-Mark gauge over the Kadee gauge as it's less subjective and a go/no-go fit

https://micromark.com/collections/model-train-tools/products/coupler-gauge-for-ho-standard-gauge-1

On a long train and pulling up grades, plastic couplers will bend and slip apart, so replacing them with Kadee couplers solves those kinds of problems.

Ted Curphey
Ontario, OR

In MY case, I am running two fifty car trains with 36" curves and 3% grades and the only uncoupling that occurs are couplers missing the spring near the bottom of the downgrades.
JB

calsubd Wrote:
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> 5 Make sure the KD trip pins are clearing the rail tops

I've noticed all Kadees which match my height gauge, the trip in is very close to the rail top, so I'm in the habit of bending all of my trip pins up very slightly

I'd agree that Kadee #5 or the whisker equivelent will lbe the most reliable when mounted correctly.  I like the appearance of the "scale head" #158 Kadees and they work well for me.

Plastic couplers will cause issues sooner or later.  I did run trains with them on a few occassions.  I found the McHenry on Athearn Genesis engines have jammed open or shut on me.  They look nice but aren't reliable.  I tried running a train of 20 Athearn RTR Hi-side gondolas and then it stopped and started on a modular layout they would uncouple in different parts of the train.  They came with the McHenry couplers with the "finger" closure spring.  Having sat in the boxes the became fatigued and didn't reliabley stay closed, so the cars would come apart. The McHenreys design later switched to a metal spring, similar to Kadees and worked better but I've been switching them out for Kadees.

Cheers,
Jim Fitch

 

I'd agree that Kadee #5 or the whisker equivelent will lbe the most reliable when mounted correctly.  I like the appearance of the "scale head" #158 Kadees and they work well for me.

Jim , I tried the 158's, but already having so many #5's I decided to stick with them, 
Ed

Ed Stewart
Jacksonville, FL

In addition to the above good advice, make sure your trackwork doesn't have any vertical bumps or raised areas that can cause longer cars couplers to slip apart.

I would advise people now to avoid the #5 now because that old spring plate has proven to be trouble and unreliable over time. The whisker #148 and #158 couplers are so much more reliable over the long term. While I still have plenty of #5's in service that operate perfectly, I have had several that have stopped centering properly and even graphite doesn't solve the issue. They were already compromised as the spring doesn't apply even pressure on both sides by design, and they can get more worn out with use. So more and more they come as bad with use.

Ted Curphey
Ontario, OR

funnelfan Wrote:
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>
> On a long train and pulling up grades, plastic
> couplers will bend and slip apart, so replacing
> them with Kadee couplers solves those kinds of
> problems.

^^^^  THIS!!!

This is a really insidous drawback to plastic couplers, because after the plastic coupler snaps back after the flexed shank causes the uncoupling, it will still measure up to proper coupler height.  As stated above - replace with metal couplers.  You might wonder how I wouold know such things, but I'm sure you can guess...

With good trackwork, I've had good experience with Kadee scale head couplers as well as the tradiitional #5s and the newer design whisker coupler replacements.

One other thing that can cause uncoupling issues is if the glad hand interferes with something on the adjacent coupled piece of equipment - either a loco pilot or sometimes even an air hose on a more detailed car.   I've taken to using a small pair of pliers and twisting the gladhand to offset it to the knuckle side of the coupler a bit.  Looking at the coujpler from the bottom, I twist the glad hand to about the 10:30 clock position.  After this adjustment they still work great on uncoujpling ramps and for doing the "side reach" with an uncoupling pick.

- Norm



 

Plastic couplers are only good for smaller pikes with train lengths that don't exceed twelve to fifteen cars depending on length and grade, and collectors. That's it.

Side note, on one of the recent Athearn Train Tuesday's, they actually said they were looking at addressing the McHenry's finally. That would be great news if it happens.

I have found the plastic couples like to come uncoupled on a down hill trains snd not on the up grade trains. All changed to kedees and no problem.
Dennis

Posted from iPhone

The Athearn McHenry plastic couplers have another fatal flaw that few have noticed, other than the issues they cause. Under the spring is a plastic wedge shaped knuckle stop that is supposed to stop how far open the knuckle moves. But with a moderate pressure the knuckle will push past the stop and jam itself open. This can happen with a somewhat long train on a downgrade. The train will seperate at the bottom of the grade. Even more frustrating is the fact that spring can unstick the knuckle after the train has become uncoupled making it appear there is nothing wrong with the coupler. Just another reason to switch to Kadee.

Ted Curphey
Ontario, OR

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ChrisCampi Wrote:
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> Side note, on one of the recent Athearn Train
> Tuesday's, they actually said they were looking at
> addressing the McHenry's finally. That would be
> great news if it happens.

Athearn just published a new survey that I took yesterday.  My main wish is that they stop using plastic McHenrys and switch to Kadees.  

Cheers,
Jim