Hiddy Ho TB Members, First off, N-Scale Kato SD70M w/DCC NCE control with Digitrax Decoder, Atlas Code 80 sectional track. Tonite I got one of my Kato SD70M's out and I was going to do some speed matching with the other Loco's I have. I parked the first loco (the one I will be having trouble with) it ran fine while it was being parked. Grabbed another loco and put on the track. Went back to the first loco, and now when it runs it HOPS up and down on the Cab end trucks. I ran it slower and could not see anything in the trucks, but the backend of the truck was coming up off of the track. I took a closer look under a magnifying glass and saw nothing unusual. Any suggestions as what to look for before I break it all the down for a complete inspection. Thanks Don
You might try taking the trucks apart. I had a little ballast get into the gears and it hopped and skipped. So start with the trucks.
If you hear a ticking or clicking sound, it's usually something in te gears. Run the loco with one set of trucks off the tracks and zero in which truck's gears have debris in them. For me, it's usually dust/lint balls that have bunched up inside one of the cogs. Use a small flathead jewler's screw or needle-point tweezer to remove it. And dispose of the lint/dustball by picking it up with a piece of tape, so it doesn't end up in another loco.
Go to the Kato web site and follow the instructions under the SD-40-2 maint. section, it is the same method. Bob.
Don, I've had the same issue on several of the "new style" chassis. In one case, the loco hopped along right out of the box; a second developed the hop after a couple passes around the Sub. In each case, I dropped the trucks out and moved them manually a bit, and the hop went away. I think something gets out of place during shipment. I've not had a recurrance but I'm very leery of the screwless chassis now. I'm very much looking forward to FVM's SD70ACes. I might just sell off the Katos. That being said, I wish Kato had issued a UP SD40-2M - which have ditch lights - and that would have meant the screwless chassis. I'll use 'em if I've got to...
Don, be sure that the trucks are fully locked together. I had 2 which were not and pushed the lower plate out and locked up the truck. Rotating the motor in reverse to the jam cleared everything and then I pressed the truck frame back together. I have or have worked on over 20 of these. Bob.
Whenever I experience this problem I remove the truck assembly take a straight section of track & place the truck only on the section of track & slowly under some light & magnification push the truck down the section of track & look closely at the gears as they turn most every time there is a small piece of debris caught in the gears which makes the Loco hop up & down usually more pronounced at lower speeds, now if you can remove the debris everything is back to normal. But while were on the subject it seems I have to do this once every 4 to 6 months. Only on the new screwless mechs did Kato expect this to be a new maintenance free design I personally find it a big pain when I had no problems with the older mechs.
the trucks on the new design may partly disassemble while beeing shipped. make sure, the trucks are properly assembled and locked. take care not to bend the brass contact strips within the trucks this might cause some unwanted running characteristics. that said, i think the new design is far better than the old one. extremely smooth and silent running. also pulling power is much better than the old drives. i have 60+ of the new screwless drives and all run perfect.
To all those that replied. THANKS. Ended up being some trash in one of the gears. I now know how to remove and disassemble the truck assembly. I never knew there were so many gears in each truck. Once again thanks to all that replied. Don
To prevent this from happening I put a small piece of painters tape small enough to cover the gears holes on the bottom of the trucks. I have done this on the Sd40-2 and SD70Ace and that problem has not show up again.
Now if I am understanding you correctly you are talking about placing tape over the 3 holes exposing the gears on the very bottom of the truck right.
