I have repowered two Athearn engines and put in NWSL wheelsets (4 axles trucks). Both engines tend derail going forward through switches but do not when going backwards through switches. I have checked and rechecked the gauging of the new wheels. Does anyone have any suggestions on how do fix this problem? Is it the wheelset. the new can motors, the swing of the axles? Thanks.
It sounds like the wheels are out of gauge.
Athearn’s locomotive wheelsets (at least the old ones) consist of two halves that fit into a separate middle section. If you grab both wheels and gently twist them, you can re-gauge them correctly. Use an NMRA standards gauge for the proper distance.
Do the wheels have exceptionally sharp or thin flanges? I’ve found that some of my turnouts cause derailments because my nice new, shiny metal wheelsets “knife” between the points and the rail, while my crummy old plastic wheels glide right over the bump. You might want to check the turnout and see how much of a “step” there is between the rail and the points.
Not only does each pair of wheels need to be in guage, but make sure that they are lined up as well, in other words you need to be sure that the pairs of wheels are not offset from each other. Both can be in guage but not tracking right.
Try running without the shells and without the side partsof the trucks and see if you can see where the problem is occuring. It could be that with the drive train change that the trucks are not moving freely enough.
[#ditto]
Check the wire leads from the trucks if you replaced the metal strap connecting the trucks (I hope you did!) for interferance with truck movement.
Check that the universal slip joints can telescope in and out.
Make sure the bronze wheel bearings are seated correctly. The gear has to be centered between the wheel halves so that one side or the other does not slip pastthe bearing bracket. Also make sure the bearings turn freely.
Ditto on modelmaker51’s suggestion of checking the wiring. I’ve had a similar problem because the wiring was too stiff for the trucks to flex properly.
ditto
The other day I was looking for new NS wheels for my Athearns BB locos at my LHS. I saw that he was out of the 42" but had 40", 38", 36". All of my Locos have the same size, which turned out to be 42" sintered wheels. I know that prototypically, the locomotive have different sized wheels based in class, etc.
According to my LHS, Athearn, in their infinite wisdom, took a one size fits all approach. They used 42" sintered wheels on most of thier BB locos. If you used a size wheel that was protoypical vs direct Athearn replacement, The shorter wheel could caus the bottom of the truck and the side frames to ride on the track as well, resulting in the flanges not following the postition of the switch.
Just my $0.02
ATHEARN B.B. engines have square bearings that drop into truck sideframe slots. If this is not happening, you will have axle mis-alignment.
ASSUMING the wheel bearing’s are in-place, all wheels are the same size and properly gauged, then look to your switches (turnout’s). Wheel’s derail on turnout’s for a reason.
You will have to sharpen your observationary skill’s to correct (We are not there), but sometime’s it helps to know where to look.
I’ve done the same upgrade you have for years now, I think it might be your switches themselves. If they are older brass or have sharp points on them this would cause your derailing, recheck your guage first and go from there. and run the engine with out a shell. When running the loco through the switch, run it as slow as possible and have a flshlite handy to follow each side of the loco as it runs to find the point where and when it derails.
Let us know what you find.
I have used the 40" wheels on both 4 axle and 6 axle, no problem. My money is on the bearings.
Jim
Did you wire the truck leads w/ too stiff a wire? Hold the loco upsidedown and sight the wheelsets. There should be slight movement of the axles, yet in this position all axles/ bearings should be seated and aligned. Although it is very difficult to assemble a truck with the square bearing not seated, it is possible. Check to see if the removed truck is free rolling and that it has no teeter/ rocking from the sideframes(steel) not being properly aligned. When I replace wheelsets this is always checked, if repeated attempts at snapping the halves together still allows the truck to rock, I file the bearing seat(square notch) until all 4 wheels have same contact on level track. You would be surprised what a difference this makes for traction. A twisted truck will have only force on 2 of its diagonally opposing wheels and will slip much easier.
Bob K.
Thanks for the suggestions. I will check the wiring as it may be a bit stiff. The alinement of wheels back to front and in the wheel bearings may be worth looking at. Again many thanks to everyone for the suggestions.
It was the wheel bearings - thanks for all the suggestions.