hi,I purchased one of the new atlas gp38s which surged(jerking motion) when running both forward and backward at any speed. It also had a very noticeable gap between the walkway and long hood on the right hand side. The LHS ordered me another one which just arrived and it too has a slight gap in the walkway in the same location but runs great moving forward but it too still has a slight surging or jerking motion when running in reverse. I ran it in both directions for about 20 min. each way and so far no change. I am new to n scale and wonder if there something else I could try or if this is something that will go away after more run time. Thanks Wayne
the surging might be caused by dirty wheels or dirty track, your powerpack may be going or doesn’t have enough juice, or the pickups may not be touching very well. how new are the GP’s?
Thanks for the reply.The gp38 in question is from the just released atlas run. I use a Kato power pack and Kato unitrack which I have just cleaned. just to make sure I ran another atlas loco from a older run and it runs just fine. Wayne
Just a thought here. I own 4 Atlas RS3’s and are fantastic runners in N scale but I had two of them that at first were some what jerky. After checking them over and just for the heck of it I removed the body shell and loosened by a quarter to half a turn on the two split frame attachment screws. My thinking was that the torque setting for these may have been to tight at the factory. My thinking was right as this fixed the problem and they are great runners. Have had no more trouble with them. The two engines mentioned were purchased a little over a year ago so that should fit your purchase time frame. Yes I do have decoders in these and I have real smooth running on Digitrax DCC. Doug
Thanks, I read about doing this else where but I thought it could be something else since it runs fine forward and only has surging going in reverse. Being new to N scale I thought it would be good to get some advice. If its a easy fix or something that will clear up with more run in time, then it could save me the trouble of returning it also. My other older Atlas runs fantastic as well as my Kato does. thanks again to both of you, Wayne
All of my N-Scale Atlas GP38’s and GP38-2’s run great.
Only dirty wheels seem to be a problem. Clean them and it’s back to awesome.
Check the play in the worn gears. You will see that they move back and forth depending on the direction you are traveling. Sometimes they will do fine in one direction and bind in the other. If you have alot of play try switching them out, front to back or you may have to shim them.
Are they DCC equipped and are you running them in DC? I had the same problem before I switched to DCC. Either switch to DCC or get a DC equipped version. Mine did not run well on DC (mine was DCC equipped).
I have not yet checked the worm gear, but after running it some more I believe it has smoothed a little. The first one I picked up jerked in both forward and reverse and was somewhat worse so I returned it (it also had a sizeable gap between the shell and walkway on right side). Both are DC. I was really wanting to make this one work because when reordered, the 1st road number was already sold out. I also had an issue with the handrails coming off, but got some excellent advice on reinstalling them in another post. This forum has been a great help and learning source, thanks to all, Wayne.