Something that I’ve encountered from inheriting old trains from my uncle, and finding the old locomotives and rolling stock that I had when I was a kid was horn hook couplers. Since they aren’t compatible with knuckle couplers, which are the main choice for modelers nowadays, I found the need to switch them out with knuckle couplers so they would be able to run with the newer models and rolling stock I’ve purchased. To begin, you will need a clear workspace, and a good light source.
I chose to work with a Satco lamp, because it was portable, and would fit into most spaces due to its narrow base. Since its design makes it top-heavy, and prone to falling over, I duct-taped it to the table.
The only tool that you will need is a screwdriver. I find that it is easiest to work with a set, as some models have different screws, and with the old Tyco models, you just need a flat head bit to lift up the flange. There are many options out there, but in my opinion, the best two are either a screwdriver with removable bits, or jeweler’s screwdrivers.
I decided to use some Tyco tank cars as examples of what Tyco coupler systems look like.
First of all, the Tyco couplers were the easiest to change. All you have to do is lift up the flange that holds the coupler’s ring in place, and slide the horn hook coupler out. You will need to lift the flange with a flat tool. As I said, the easiest way in my opinion is to use a flat head screwdriver. After you have taken the old coupler out, just slide a new knuckle coupler in. I used Scene Master Knuckle Couplers as replacements because they were the cheapest option out there, and I would warn against using Kadee couplers on Tyco cars because the Kadees are a looser fit than the Scene Masters.
This newer engine is a more common example for a coupler change. This is an unfinished C44-9W Southern Pacific engine that I’ve been working on.
Your first step should be to unscrew the screw that holds the coupler into place. Remove the old knuckle coupler, (which can be tricky, especially if you’ve already installed the front plow) and replace it with a new knuckle coupler. In this case, I had to use a Kadee coupler, because the Scene Masters knuckle couplers had holes that were too small. It is much harder to put the screw back in again if there is no well for the screw to go in, as was the case on this engine. Make sure not to screw the screw in all the way, so that it can still move back and forth for when going around curves.
If you have any further questions, you can message me on the site, or on facebook. Also, consult this website: http://www.kadee.com/htmbord/helpful.htm (Kadee.com)
I would suggest asking Sam the Answer Man.