ive got a few cars that randomly uncouple. ive checked there heights and all is good , but it seems that while they are running they creep down or up (not sure) and uncouple them selves. they are knuckle couplers mt i think. the cars with rapidos never uncouple or creep up or down. any suggestions. they all couple good but when running they creep up or down then bamm train wreck. then i have to send out the crane to clean up the mess (only got one crane )
Does it happen every time? Is it always the same two cars? Is there a 4% change in grade? Are they older? Cars or trucks?
Are they truck-mounted or body-mounted couplers? Something you may want to look into is the Micro-Trains Slinky Effect. It could possibly be happening to you, and the slack action is forcing cars to become uncoupled.
If they indeed creep up/down and then slip off each other (especially under a pretty good load), it could be a well know "draft angle" issue. MT actually addressed this a number of years ago with their "reverse draft angle" couplers, which I think has since become standard on their couplers. That said, some older MT couplers might still be out there. If this is indeed what is happening, there is a rather tedious procedure to trim a reverse draft angle into the pulling face of the coupler with an Xacto blade. Would have to look around for that info though.
First, you want to make sure it's the creeping up or down that's actually causing the uncoupling because it could appear to be but not be. The other common cause of unscheduled uncoupling is the two halves of the coupler not returning to their rest position each and every time they are spread apart and released. If they don't completely go back together, uncoupling is almost assured if slack occurs and then is taken back up. The open "jaw" allows the knuckle to slip out of the pocket formed by the two coupler halves together. Take each car and spread the coupler halves with your fingertip and then release the two hales VERY slowly and make sure the two halves completely move back to the center and close. I am assuming you are using MT couplers. Doug
One possibility if they are old MTL is they don't have a reverse draft angle. Pix and fix: https://www.therailwire.net/forum/index.php?topic=50768.0
Atlas Accumates are notorious for mid train uncoupling. It is pretty much the only issue I have while running if it happens, I'll turn the car around in hopes it won't happen again, and sometimes it won't. But I run long trains. I brought the crude oil train out yesterday and it uses the BLMA tankers with MT look alikes and had three separations - most unusual.
There can be a number of things causing the uncoupling. Some are enumerated above. Not mentioned is the length of the train and where this happening in that train. Additionally, the rolling resistance of individual cars may also be a cause. Not all cars will roll alike even if equipped with MT trucks and couplers. My guess, from the description provided, is that there is increased rolling resistance of certain cars coupled with (no pun intended) the reverse angle issue.
I have read this thread 3 times now and do not see any mention about where on your layout these breaks happen. Is it in the same are each time. If so, check the track for dips and especially notice if it is happening on an interface between two sections of track. If in a track joint make sure the rail joiners are under the rail properly and not actually having the rail above the joiner. That cold cause a bump that may be enough to cause the unscheduled uncoupling.
# 1 no its different cars # 2 no grade flat running but are coming out of curves at two different areas # 3 yes older cars upgraded truck mounted couplers
yes they do indeed creep for sure . they can run several laps and no problems what so ever then out of the blue they becoming disconnected. i watched them run and about every two to 5 laps this happens. ill have to search for that info Thank You
there for sure creeping up or down i watched them every few laps 2 thru 5 laps sometimes more laps sometimes less.
there for sure creeping up or down i watched them every few laps 2 thru 5 laps sometimes more laps sometimes less.
carl never in same spot but always around curves (well just coming out of them ) its two different locations but not in the same spots. i watch the train run and watch those couplers after a few laps they creep either up or down not sure witch. Thank you
ive tried that as well as putting them in different locations sometimes its the same cars and some times not. but its always towards the end of the train like 4 cars in from the end.
If it coming out of curves are the coupler shanks moving freely from right to left as they should. It could be, if they are old and do not have the reverse draft angle feature that the coupler on the second car out of the curve is staying over too far and the one on the lead car is moving freely causing them to pull apart because there is no rda. I know, clear as mud. Just trying to think outside the box.
Carl this may well be one of the problems . im still running trains and watching very close . ill have to put it all away for a week or so. i must leave town for a while. ( the law is getting to close ) hahahahaha just kidding. going to visit grand kids and maybe move daughter an grand babies back with us ( i sure would be happy about that. i miss them dearly .
