Inventive Models appeared on the scene in 2022. The company is based in mainland China. Owner Eric Xing posted for sale on eBay HO- and S-scale brass couplers based on the Frank Sergent design. Frank made his design part of the public domain when he retired Sergent Engineering. These are couplers that work very realistically, in that the coupler head has to be opened to uncouple. A magnet is waved over the couplers to raise an internal ball (or whatever the mechanism is) that unlocks the head, so that the cars can uncouple. When the cars couple again, the ball falls down and the coupler head is locked. The big difference between the Inventive Models couplers and the Sergent couplers is that they come already assembled. That saves a big part of the hassle. These are a bit more expensive than the Kadee and the various HO-scale couplers, but they offer a lot more realism. The couplers do not come with a draft gear box, so you have to find one yourself. The photo shows the top and bottom sides of the couplers. The small spring is to be inserted into the groove (visible in the top couplers) to act as a sprung buffer when coupling. These are really tiny springs and they are susceptible to static electricity, which makes them very difficult to handle. Fellow S-scale modeler, John Degnan, collected a large order for us S-scale modelers to give us the volume-discount and cheaper (per-person) shipping rate. He wound up placing an order for 1,300 pair of couplers; not bad for S-scale. I only ordered 7 pair, because I wasn't sure how they worked and whether or not I'd like them. But the fact that the HO-scale Proto MAX couplers no longer come with coupler boxes either, I am planning on converting my fleet to these true S-scale couplers. So, I'll be placing a second, larger order when the time comes.
(external link: Inventive Models)
To install these couplers onto my equipment, I decided to buy some urethane-cast coupler boxes from Smoky Mountain Model Works (part #64-DP-707-BK). In my workbench parts box, you will find all the parts needed, which, from top-left to bottom-right, are: SMMW coupler box top lid, the core coupler box designed for the I.M. coupler, riveted plate part, long screws for attaching the coupler box to the car, the I.M. coupler, the tiny springs for the I.M. coupler, and the larger self-centering springs that fit between the back of the coupler and the coupler box.
(external link: Smoky Mountain Model Works)
This photo shows an example installation. The back end of the coupler box is supposed to represent the continuation of the center sill of the car, which you need to trim to length as needed to fit your particular car. The two screwholes perfectly lined-up with the holes cast into this S-Helper Service box car. The first coupler I installed took me quite a while to figure out and I wasn't happy with the installation, so I had to redo it later on. The second coupler went much faster, and was a success right away. So, a bit of an initial learning curve, but very much doable.