Greg Elmassian said:
I did not have the time or environment to watch the video at the time I posted… sorry, did not mean there was an issue with the post.
Greg
Phew! I’m glad you said that. I thought there was a new problem in this convoluted problem. (https://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)
Nicolas,
Here is what I see with your video. (which I reviewed NUMEROUS times and the slow motion really helps however I only found that part of the video 10 minutes after rewinding back on the original speed before I watched it to the end …hehehe…)
1…Your locomotive is traveling too fast for that curve (consider speed restriction which is quite prototypical)
2…USA couplers really are not the best but I don’t think it’s a coupler issue. “Notice how the locomotive yaws hard” going into the curve.
3…If you insist on that speed then try super elevation on the track which may or may not fix the issue.
These are only a few of my observations. I actually do have a little experience running rather large locos and cars at speed with 10’ diameter curves with body mounted couplers as well …
Ran the engine with the adjusted coupler range for a while without issue. Looks like extending the range should do the trick.
Glad to hear that. (https://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-laughing.gif)
Great news, I bet you are happy you don’t have to adjust the grade!
Yup. It is definitely the easiest of the things to change.
So to recap, is the current thinking:
coupler swing limit reached early in curve
this side pressure locks couplers together, not allowing couplers to slide up and down naturally
as the loco hits the top of the grade, the rear coupler lifts and also lifts the truck of the trailing car
as the swing limit is “relaxed” the couplers are no longer locked together, and the release of the lock allows the trailing car truck to drop back down, exceeding coupler overlap and uncoupling.
Just like to learn from these things. Wondering if you think this is what happened.
Greg
This seems reasonable. The issues I ran into were both when the engine is going down hill and both coming into 10’ diameter curves. Your explanation would also match with what I saw, with the problem not always being reproducible. When it didn’t happen you could definitely see the couplers slide vertically. Reduced swing locks the couplers together preventing them from shifting vertically which causes the engine to lift the trucks off the track causing a derailment and uncoupling.
Well, it’s a valuable lesson to learn. Will add this to my SD70 tips page.
I’ll link to your video if you don’t mind.
Greg
Go for it. I am using 10’diameter curves so I didn’t remove the spring like the instructions on the SD70 page showed. See photos I attached.
done:
https://elmassian.com/index.php?option=com_content&view=article&id=276&Itemid=308
If there is anything else you want to add, let me know.
Greg
Looks good.
