The resolution of the mystery derailment at turnout 5 continues to elude me. I’ve spent hours watching that leading wheel of the tender truck kissing the rail and floating off at the critical point. The more I watched it, I became less and less convinced that it was ever in proper contact with the rail. Well, that is just no good in Proto:87.
Each truck on the Bachmann tender feeds power from one rail. A phosphor bronze wiper rubs against the axle and connects to the kingpin screw. The nut on the top of the screw rubs against a washer, which is soldered to the decoder. In order for all the connections to work, the kingpin screw needs to be relatively tight. That means that both trucks are rigid and unable to equalize relative to one another.
To make matters worse, the end of the wiper fouls against the wires connecting the locomotive to tender. I’m not sure what effect that is having, but with a wheel in the air, it’s unlikely to be good!
Perhaps it would be sufficient to revise the current collection so the trucks equalize and nothing contacts the wires. However, with the truck clearly not tracking properly, I would like to try to equalize that as well. So, I grabbed a truck sideframe I had designed previously and, inspired by a Kadee HTC truck’s cunningly elegant approach to equalization, I designed a bolster to build a whole truck.
The two halves of first print were a press-fit due to the surface inflation I seem to get with the printer. The version shown here looks too sloppy, but it’s already printing. I’ll be taking another swing at it tomorrow.
Pembroke:87 