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About the Model Railroad

RTAC Software


The Randall Museum in San Francisco hosts a large HO-scale model model railroad. Created by the Golden Gate Model Railroad Club starting in 1961, the layout was donated to the Museum in 2015. Since then I have started automatizing trains running on the layout. I am also the model railroad maintainer. This blog describes various updates on the Randall project and I maintain a separate blog for all my electronics not directly related to Randall.

2018-08-22 - Something Unexpected

Category Randall

This was rather unexpected:

The passenger automation currently runs with two UP engines. Then once the passenger train goes back to the station, the RDC goes out. Although they use the same track, they shouldn’t be on the same block at once.

What happened: Annoyingly, the two UP engines uncoupled. Then they drifted apart across several iterations of the automation cycle. Eventually they got separated enough that one would reach the station and end the cycle while the other one was still on the mainline. Then the RDC tried to run and simply collided into it. And then stopped working.

Back to the bench, and the oh so fun exercise of opening the RDC to access the motors:

OK so I see why it’s not running. The rear motor doesn’t spin as easily as the front one. It starts spinning and gets stuck, unless I put more power or give it a tiny push on the flywheel. That’s oddly exactly the same behavior the original motors were doing before I changed them.

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