# Cars uncouple randomly



## Ronk (Sep 13, 2019)

I am new to model railroading, I am retired and have a lot of time on my hands so I decided to try my hand at this hobby, it is something I have wanted to do for a long time, but never had the time, space or money. I now find myself able to give it a try. I have read books and articles on layouts, wiring, DC vs DCC, what controllers to use. I have checked my layout to insure it is level, but at random the cars will uncouple from each other or from the engine. I have checked the connectors but find them to be in good shape. The only thing I can come up with is the couplers are not matching up. can any one give me any advice on what to check for and how do I insure that the that the couplers are lining up and how to adjust if they are not lined up properly.


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## Dennis461 (Jan 5, 2018)

HO or O or N? Picture of couplers?


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## flyboy2610 (Jan 20, 2010)

More than likely your couplers are not all at the same height. The NMRA (National Model Railroad Association) has developed a standard for coupler height. You will need either an NMRA gauge (this one is for HO scale):
https://www.micromark.com/NMRA-Gage-HO-Scale_2

or a Kadee coupler height gauge
https://www.kadee.com/dynamic_filter?main_page=index&cPath=81&sort=20a&fltPRODUCT[]=Height_Gauge
I would actually recommend getting them both, but if you can only afford one, get the NMRA gauge. It can check a multitude of things on your layout. As for adjusting the height, there are a multitude of videos on YouTube dealing with the subject that explain it better than I can.


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## gregc (Apr 25, 2015)

Ronk said:


> I have checked my layout to insure it is level, but at random the cars will uncouple from each other or from the engine.


are they the same brand. A very common coupler is kadee, but Sergent is another type that if often shipped with cars. (google images for both). keep track when they disconnect


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## mesenteria (Oct 29, 2015)

I can think of at least four possibilities:

a. Couplers' height disparity (already mentioned). They may meet okay on level or steady grade tracks, but at vertical curved transitions into and out of grades, they shift and will part);

b. One or both couplers are not securely and stably mounted in their host draft gear boxes. They can wobble up and down);

b. Trip pins are snagging or swiping something, possibly a guard rail, and the coupled items eventually separate when resistance disparities force them apart; and

d. Something is preventing the couplers from swinging in azimuth sufficiently to keep them coupled. It might be curves too tight, diaphragms between passenger cars too stiff, flashing on plastic sills or bolsters, or appliances that the couplers butt up against in their swings to the side.


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## wvgca (Jan 21, 2013)

it could be something as simple as track ... if it's not level between sections it may give some trouble, like disconnects ?? just a suggestion ..


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## prrfan (Dec 19, 2014)

You might also check that your locomotives are operating smoothly. A lurch or hesitation can cause cars to uncouple, especially if they were not solidly coupled to begin with, for whatever reason. 
Clean track and locomotive wheels, and make sure track joints and connectors are good everywhere.


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## CTValleyRR (Jul 26, 2014)

All good advice so far. Let us know what you find.

Just remember that if you are going to get one or both of the gauges flyboy mentioned (and you should) that they are gauge specific -- make sure you get the right one, not (necessarily) the ones he linked to.


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## DonR (Oct 18, 2012)

I have both the Kadee and NMRA gauges. I think the
Kadee model is easier to use for aligning couplers, especially if you get the plastic version that can straddle a live DCC track.

Kadee's has height for body mounting, height of
knuckle, and proper 'hose' adjustment to avoid
catching on turnouts.

Don


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## Deane Johnson (Sep 19, 2016)

I'd echo what DonR says. The Kadee guage let's you get it right. I have the NMRA guage but have never used it for that purpose since I have the Kadee version at hand.

On the issue you're experiencing, the one thing you've got to get right is the couple height and the clearance of the trip lever. Only when those are right can you start looking for some other reason you might still have a problem. After the couplers are at the right height, and the problem still exists, I'd start looking at any plastic couplers. There's a reason most all of the experienced modelers get those off their equipment and replace them with Kadee. I buy the whisker version in bulk and absolutely love them. Easy to install and seem to me to be the most trouble free.

Deane


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## Jscullans (Jul 8, 2019)

If you’re mixing coupler types that can cause issues too. I remember having hook horn couplers as a kid and trying to use them with cars that had knuckles and they don’t jive well and come apart consistently


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## CTValleyRR (Jul 26, 2014)

Unfortunately, the OP has not been back since he posted this question...


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## flyboy2610 (Jan 20, 2010)

CTValleyRR said:


> Unfortunately, the OP has not been back since he posted this question...


One of them one hit wonders, eh?


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## prrfan (Dec 19, 2014)

Jscullans said:


> If you’re mixing coupler types that can cause issues too. I remember having hook horn couplers as a kid and trying to use them with cars that had knuckles and they don’t jive well and come apart consistently


They not only can come apart, they can also violently derail. I was messing around one day running mismatched couplers and wound up putting most of the train on the floor. Comes under the category “Don’t try this at home.”


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