Black Paint on Truck Sideframes - YMV 200/201/552
Once the trucks were disassembled, care was taken to mask the wheel and gearbox combos as well as all of the machinery above the frame. The truck side frames themselves were left "attached" to the main locomotive by a single soldered wire for electrical pickup.
On the Athearn Genesis models, the metal contact strip which completes the electrical circuit from the axle ends to the jumper wires leading to the circuit board are "riveted" to the inside of the truck side frames with melted plastic tabs. To maintain the integrity of this electrical path, masking tape was applied over this strip at every axle contact location.
Since the wheels on Y&MV SD35 552 had not been painted yet, I decided to include this unit in the process. Truck disassembly with this Atlas locomotive was a bit easier than on the Athearn Genesis GP7u's as the metal axle contact strips were not fixed to the truck side frames, allowing them to separate completely from the locomotive. Both the wheels and truck side frames of the Y&MV 552 were painted at the same time as those of the GP7u's.
The truck side frames were airbrushed with a thinned coat of Floquil Engine Black. The molded silver plastic truck side frames on the Athearn Genesis GP7u's actually have a repellent property which caused the Floquil paint to run away from the corners and details. I did not notice the effect on the black plastic Atlas side frames, though it would have been harder to notice due to the plastic and the paint being the same color.
This time the paint went on very smoothly and evenly. There was no evidence of the repelling effect that the naked plastic had on the first coat of Floquil paint.
The project was put aside for a few days to dry thoroughly. The side frames on all three locomotives were put back on the locomotive truck assemblies. On each of the GP7u's one of the truck side frames came lose as the wire broke at the solder location. As the circuitry is redundant the locomotive operate just fine under power. The wires are VERY thin, however, and certainly the integrity of the remaining six connected truck side frames may be compromised.
These electrical contacts will be revisited during the DCC decoder installation process.