Hey there, I just got around to test fitting a newly acquired tunnel motor and will hopefully be doing the same to an SD45 in a couple days. Off the bat I found that the T-2 does not like trying to negotiate 18" radius curves and still struggles with 22". I have also found that when testing it with cars in tow, the length of the frame makes the drawbar swing out far enough to derail the first car it’s pulling, due to the shorter length I don’t know if the 45 will have the same problem. I would like some feedback on what the suggested minimum would be as I am trying to fine tune the plans for a 5x9 layout and I want to be able to allow these to run on it without any issues.
Razor, while I don’t have the SD 45 or a SD 40T-2 I do have a Athearn RTR SD40 2 and SD 50’s. They will take 18 inch turns with no issues. Make sure your wheels are in gauge and check your tracks for uneven spots. 6 wheel engines get real picky. Center wheel will make the truck’s front wheel come off the rails if there is a high spot.
All so pull the shell and make sure the truck has full range of movement. Trying running them around the track with out the shell. I had a edge of a step cause a derailment issue with a PK SD7.
On some of my longer engines I do have to run long shank Kadee’s.
Good luck
Cuda Ken
I have AC4400’s, SD40’s, 50’s & 60’s & they will all take an 18" curve. The wider the better, but 18" is possible.
Gordon
Althhough I do not presently run my pair of Athearn RTR SD45’s on my switching layout, I have had them on it. The only turn on my layout “main” is a 24" radius. But, the pair have been over the No. 4 Atlas turnouts without a hitch. As mentioned above, check the swing of the trucks, as well as how much "play"in the swing, which may be too tight. On another note, I do have a Stewart U25B (a four axle unit) which has derailment problems on some of the Atlas No. 4 switches and I do suspect truck problems there; haven’t played with it yet to correct the problem as it is not an active unit on my layout at this time as well.
My T-2 was a royal pain, it hates 18 rad and due to the longer wheel based truck the flange to rail in curves is very tight. It also does not like the inside curve of a curved turnout.
as stated above a longer draw bar should work, you can also find a car in your fleet that has enough swing and run it behind the unit.
Check it on a sheet of glass to be sure truck isn’t warped, all wheels should touch, also rock it to the side to see if all wheels raise the same.
I ground my t-2 frame to get more truck swing and checked it with a piece of 22 in rad snap track, this is so you can see it at different angles as you roll it over, hand holding the track and engine.
being the longer truck distance check the inside of the rail, easy to see by sliding your fingernail over the track, the flange will climb every easy at the front wheels, especially in curves. run it very slow on the layout and set a marker at point of derail, move engine and examine track at derail point. check inside of rail with fingernail to see if it is smooth, if not correct it by using a smooth file and recheck it.
Hope this helps
John
Tight radii are a pet peeve of mine, and I realize spec is tight for some folks. As some report, many longer engines are made to work on 18-inch curves but it’s really a torture test and they don’t look pretty even if if Athearn managed to engineer tunnel motors in order to “trick” them around such tight radii as 18-inches. I’d recommend 24-inches as a minimum for those just to keep from all the trouble. I suppose the problem is some folks followed the industry convention of snap track (18 and 22" curves, and later when they buy diesels and rolling stock they find out that those curves are not too friendly.
Conventional wisdom based on experience in the hobby is you should limit yourself to short 6 axle loco’s such as the SD7 and use 40 and 50’ rolling stock if you are using 18/22 inch curves. As you can see, SD40T-2’s, depending on the person, may or may not manage these tight curves - they will need some tweaking in some cases.
As for derailing cars, it’s a bad idea to couple short cars to a long loco and operate them on tight curves - a recipe for derailing. It’s better to keep the lengths similar to avoid that issue if possible.
Tom, check out the bottom “truck cover” of that Stewart U25B, you may have the same problem as others w/ the molded protrusion of the cover causing a clearace issue. This can be filed even if you break through to the gearcase. I used to hang up on slightly high uncoupling magnets.
I’d do a “reality check”, go to the local hobby shop and buy some Kato or Bachmann curved “click track” in say 24", 26" and maybe 28" radii, and see what the equipment will actually run thru the curves. Manufacturers give out minimum radius info on their models but it’s a good idea to try your models out yourself.
BTW I’d also avoid No.4 turnouts, turnouts that are No.5 (if available in the type of track you use) or larger are going to work and look better.
I agree as far as the track goes, except if this person has a 4x8 layout, the KATO larger curves may not work. You need both the table or benchwork that can support the curves, but I think he should enlarge them rather than suffer the effects of tight curves.
I agree on the turnouts too. I’d stick with #6 turnouts too.