Has anyone experienced with the USA trains SD70 Mac problems with the truck steering not staying on the tracks even around wide radius curves. It seems like the design of the pivot truck is flawed that it's too light and does not have enough of movement to keep it properly balanced. Maybe extra weight is needed or what USA should have done is what Aristo did with their trucks by having the center wheel pivot back and forth similar to an articulated truck and that is used in other scales too. I also think with the USA design that the truck is off center in which it will make it prone to have these problems of tracking properly. I hope someone is out there that has a fix for this problem so I can bring it up to USA trains with it.
I have no experience with the big USA locos but there are a couple of things I can suggest. Is the loco always derailing in the same spot? If so, you may want to check to see if the track is level or if there is a dip. Also you may want to check if the wheels are properly gauged. The relatively new Aristo track level, gauge and wheel gauge is a very handy tool for $10.
-Brian
Age is only a state of mind, keep the mind active and enjoy life
No it does not derail in the same spot it has nothing to do with the gauge of the rail or the radius or even the code it is the truck does not have enough of swivel movement to properly stay on the track. The reason is they are not heavy enough lack of weight. It would help if the truck side frames were diecast or the underframe that would provide enough of weight to help it track better. Still it would have the problem of the swivel motion. Also The USA SD40-2 has the same type of drive. If you compared the 6 axle Aristo Craft SD-45 and Dash-9 etc. vs the USA 6 axle you will see the powered truck design difference. That is why I am posting this to see if any one else has these same issues with USA trains 6 axle locomtoives. As of a fix before I contact USA with the problem and fix.
No, I've had a couple through for conversion.
No issues that I can recall.
Don't these have the curved-slotted guide under the frame?
Have you had anything apart?Like, reversed the guide?They are fixed to the frame by that slot, no weight or spring issues to deal with.
How does the pivot axle function with the loco upside down?Does it swing freely through the arc even when the main truck is turned?The wheels rotate okay, as in you didn't drop the driveshaft out?Does it do this on both thrucks?Does it do it backing up?If not, can you see anything assembled differently on either end?
"prsl-sj wrote the following post at 03-08-2008 9:39 AM:
Has any one replaced the USA trucks and put Aristo-Craft trucks under the SD-40-2"
Why would you?
As is stands, I did and do have several here, on track power, no derailment issues.
On battery conversion, out on the railroad, no issues.
All curves, all grades, all wheels stay on the track.
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