I disassembled some Walthers heavyweight, six axle passenger trucks to paint and apparently didn’t get the wheel sets back in the right order as the voltage on the track drops noticeably with the car on the tracks. The truck frames and wheels are metal but the bolsters on my kitbashed car are plastic. The trucks do not touch anything metal on the car like the couplers or the brass draft gear. I would assume they are designed to power internal lighting. I did try rotating the trucks but that did not solve the problem.
Therefore, I must have the wheel sets flip-flopped. When I look at the wheel sets in the trucks I can not see any difference to tell me which side is insulated.
Can I tell when I disassemble the trucks again and take the wheel sets out? By the way, avoid disassembling them as they are a real pain. It must have taken me a half hour to get them back together. The four pins that hold the ends of these trucks on both ends are difficult to align and quite small. I was forewarned but did not heed the warning! Never-the-less, they are nice trucks.
If you have trucks with metal sideframes, metal axles and metal wheels where the wheelsets are insulated on one side, then the insulated wheelset ends must all be on the same rail. Otherwise there will be a short circuit as the flip-flopped metal axles will be of different electrical polarity.
A circuit testing device such as an ohmmeter can help you find the offending axle. All of the wheels that have an infinite resistance between wheel and axle must be on the same side of the truck.
If you examine the axles very carefully, there should be a small plastic insulating collar on one wheel. Make sure all the wheels with this insulation are on the same side on each truck, and that they are on opposite sides of the car at the two ends; i.e., one end with the insulated wheels on the right rail and the other end on the left rail.
The Walthers wheelsets have plastic axels so you should have no problem with the wheelsets. On the Walthers car electrical pickup for car lights is via the metal sideframe and the screw heads that attach the sideframes to the bolster. The screwhead slides on a metal tab under the floor.
Are you using them on Walthers cars? The Walthers cars do not have brass draftgear.
The car is a kitbashed plastic (more like scratchbuilt) car I built for a friend. I attached PSC brass draftgear to the car ends and the Kadee coupler boxes with tapped, brass 2-56 screws. The coupler boxes are plastic but the couplers, metal. As far as paint, I used Scalecoat paints.
I’m not for certain what the problem was, or it could have been a combination of things. But I replaced the brass screws with nylon ones and also replaced the metal bolster washers with homemade plastic ones. Everything seems to be fine now.
The first thing I did was take the trucks off and put them on the track without the car at full voltage and there was NO short. That told me that there wasn’t an inherent problem with the trucks but something in combination with the trucks and the car. (And therefore, I didn’t have to disassemble them again!) I am thinking that the screws on the trucks used for car lighting or another part of the metal truck frame was touching the draft gear, a brass screw head or somehow the washers caused the short. I noted that the problem was more acute depending on which direction the car was placed behind the loco so I suspect that the brass screws attached to the draft gear that ran through the metal coupler shanks were transmitting voltage too, though it may have started with the bolster washers. (The loco’s couplers are plastic.) Another thing I should mention is that I epoxied Athearn car weights to the inside floor of the car. I also epoxied nuts for the bolts to the floor and inside the holes in the car weights. The bolster bolts make contact here. If for any reason the bottom side of the truck and the top side of the truck are opposite polarity, that would cause the problem too.
Incidentally, from what I could determine from testing and what I am being told, the axles are plastic or split and covered with plastic sleeves so that all wheels can pick