Several years ago I purchased a “how to” book called “Model Railroading with Athearn Trains”. The copyright date is 1989. The articles described the many ways to improve the performance of Athearn diesels. One article in particular described how to get more left/right play in the wheel sets. This was especially important for “C” or 6 axle diesel (SDs) wheel arrangements since it allowed the center wheels to stay on the track around tighter curves. This was an easy fix since the Athearn wheel bearings at that time were in the side frames. File down the brass bushings and BINGO! more left/right wheel play. It worked great. Its not so easy on the newer Athearns. The bearings are the small square brass nuts and I have not been able to figue out how I can add the additional left/right play I need on this type wheel set. Any help?
Have you had any problems using the c truck in the newer style? These tend to have quite a bit of axle side play. The old metal sideframes weren’t as forgiving as you found. Generally any of the medium 6 axle will perform much better on at least a 22" radius. Are you trying to run these on an 18"?
Have you checked that the trucks can swing freely? You may be able to grind the frame to gain a bit more movement. I don’t remember on the trainmaster if the truck will interfere with the steps. Your trainmaster should easily run on those curves.
The Trainmaster should be able to go around an 18" radius without a problem, like most Athearn diesels. Have you checked to make sure everything on the trucks is clearing properly, inside and out? I remember my DASH 9 couldn’t make a left turn because the tall contact strip on the rear truck was hitting the inside of the shell.
Thanks to all who replied. I’ll check the truck swing again for interference. The model I have has very little (hardly any) side play in the wheel sets. What I’m now thinking - the wheels may be in gauge but out of alignment some way. If this correction is needed it looks like it can only be done by eye not the NMRA gauge.
Hey just a thought here, I just remembered I had some Athearn U boats C28 and C30’s that had almost the same problem. As I remember right the trucks top corners were catching on the shell, which inturn caused a single wheel set derail. It took me about a day to figure this out, I had 22" radius at the time. I ended up shaving some of the plastic under the steps on the front off the shell, so the truck could swing free in the curves.
Does this Trainmaster have the old Blue Box diecast sideframes? IIRC, they didn’t ever revise those trucks with the plastic sideframes and inside bearings. The newer trucks were more flexible, as the bearing allowed for lateral float, as well as vertical movement of the center axle for better tracking. The diecast trucks with the outside bearings were vertically rigid, and could easily derail on dips or joints on curves. The truck housing may be striking the frame on tight corners, as others have mentioned. If you still can’t solve the problem, check each truck on a piece of glass to see if it sits level, because sometimes the sidframes were out of parallel.
I know they did not revise the metal side frame trucks, the problem I had one time was with a couple of U28C’s and U30c"s, for some reson the very top of the truck on either side in front under the cab was catching the shell on the underside, right by the steps. These all had the plastic side frames on them. All 4 of them had the same problem though. I bought them all new years back and worked on them for hours until I figured out what was causing it. It did not matter which curve it was going through either, right or left, it would derail!
On the inside of the truck I took my dremel and sanded out just a tiny bit where the truck side frame was catching, it was right below the steps on both sides. It was not much material to sand out to make it clear the top side of the trucks either. Those were the only Athearns that I had trouble with. If I still had them I could get an good look at them to pin point the problem. But I do know it had to do with the front truck side frames catching on the shell. They had the plastic side frames also. Also I sanded on the shell not the truck assembly to be clear on this.
I guess Athearn missed that problem when they redesigned the U30C’s. The only one I had was the older version with diecast trucks.
The kingpins on those older BB engines were balanced on the trucks so precariously that they could really rock & roll. The later versions were more stable, with a wider bolster.