For my RSD-7 and RSD-15 projects (see WWW.ATSFNSCALEMODELS.COM) I needed Atlas C-628/630 locomotives (chassis only). So I bought a number of used/older ones on eBay. In a few cases the small black plastic universal joint inside one or both flywheel(s) on the motorshaft was broken or slipping. The problem is easily recognized: turn on the power and if the wheels in one or both trucks stop spinning when you apply a little pressure on the shell while the motor keeps going, the little black ring/universal inside the flywheel is cracked/slipping. I tried ACC glue with some succes but found a much simpler and better fix. First take some tape to protect the motor against the filing/grinding/drilling you have to do. The tape has an added advantage: the motor will not turn anymore during your work. File or grind (motor tool grinding disk) 2 small flat spot 180 degree opposite each other on both flywheels halfway lengthwise. Drill two 0,5 mm holes in the flat spots towards the motor shaft. Insert a short length of Tichy Train 020 brass wire (part # 1103) dipped in ACC. Cut/grind/file of the exess on the outside of the flywheel. I also used a flat file (about 1,2 mm thick) to clear the slots in the universal joint. The position of the two holes/brass pins is not very critical as long as they are just about in line with each other. There is more than enough play (1,2 mm wide slots versus 0,5 mm thick tabs) to ensure a friction free connection, which will never break down anymore.........! The changes to the flywheels will not cause any noticeable unbalance. It sounds like a long story but taking the chassis apart (clean out the thick grease in the meantime and replace with some light oil - your engine will run much smoother) and reassembling the engine take mores time than the work described above. Good luck, Dirk Jan Blikkendaal
COOL !!! I have a 628 whose motor runs at 9 million RPM, but locomotive barely moves. This might be what I need !!! Thank you !!!
I am wondering if this is the same problem that the Atlas H-15/16 had, where the male part of the universal joint cracks (the black part that is press fit onto the flywheel)? Evidently the orginal part would crack which would loosen the press fit and the part would just spin on the shaft. You would have to look at the part under a magnifying glass in order to find the crack.In my experience Atlas has sent replacement parts for this issue and the replacement parts do no crack like the original parts.
This is a great solution to the problem and I bet it would work on other motors with the same set up. Thanks for sharing this.
