Ballast & Bubble: differences in coupling height and solutions — Irish Railway Models Skip to content

Ballast & Bubble: differences in coupling height and solutions

We’re sticklers for accuracy here at Irish Railway Models and as modellers ourselves we’re dedicated to manufacturing products which meet exact specifications. So we understand that some of you may be scratching your heads after viewing photos of the first ballast wagon pre-production sample and noticing that the NEM coupler pockets appear to be higher than they should be. We can confirm that they are too high – by 2.1mm to be exact.

However, this isn’t a design flaw. It’s intentional and the purpose is to avoid compromising the fidelity of the wagon design itself.

As you will see from viewing photos of the prototype in our gallery section, there is a horizontal crossbar associated with the braking system situated beneath the bufferbeam at one end of the wagon. If we lowered the NEM pocket height, it would interfere with this detail, meaning we would either have to incorporate an unsightly block of plastic into it to house the pocket or lowering the crossbar itself, which would also result in an unprototypical appearance.

To overcome this issue, the wagon will be supplied with tension lock couplers with a ‘swan neck’ or ‘cranked’ fitting which will lower them to the correct height. This solution does not compromise the wagon’s fidelity and also ensures the couplings will work with stock produced by other manufacturers.

Cranked coupler fitting for Irish Railway Models ballast hopper


For customers who use Kadee couplings, the height difference can be overcome by mounting a No. 18 or No. 19 coupler directly to the underside of the NEM pocket (you’ll have to file off the IRM stamping, alas).

Kadee coupling on an Irish Railway Models ballast hopper


As the ballast hopper and cement bubble wagons share a common chassis design, this solution will also apply to our forthcoming cement bubble model.

We’re happy to report that all three ballast wagon packs are selling well. To reserve yours, head on over to our online store.


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