Diamond crossings and DCC


As someone gearing towards converting my layout to DCC, I was running a simple figure of eight circuit using Bachmann's DCC-fitted Class 25 and an unfitted Bachmann Deltic using Bachmann's E-Z Command controller. The diamond I was using was a Fleischmann Profitrack wide angle short crossing.

After a few circuits, the Class 25 suddenly changed direction and crashed back into the Deltic!

Was this due to a momentary short on the crossing? And is this a problem inherent with all diamond crossings and DCC?

I ask because I current have eight Peco long diamond crossings on my main layout, and dread to think of the consequences if this were to happen when I went live DCC on my main layout!

Thanks in advance for any help and/or suggestions you can provide.


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Lloyd Butler
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Whether for DC or DCC, crossings are a problem. If the isolating gaps occur at the frog itself (eg, a sliver of plastic molded in to separate the rails), it's possible for a metal wheel to bridge from one rail to the other. Check whether that's the way Fleischmann does it.Many manufacturers do so, since it simplifies connecting the crossing to other track pieces - you don't need isolating railjoiners. But IMO, this is a bad way of isolating a crossing.

The proper way IMO is to isolate the whole crossing at each end of each arm. Cut gaps between the frogs within the crossing. The frogs should be all-metal. Or else bond the two rails of the of the frog to each other. Electrically, the crossing will then consist of four L or V shaped sections of rail, A, B, C, and D.

For one route through the crossing, A+B and C+D will connected to power and ground respectively; for the other, A+C and B+D will be thus connected. You need a switch or relay that will energise one route and only one route through the crossing at a time. By judicious placement of detectors ahead of each arm of the crossing, you can automate this, but you will have to install mechanical or electrical interlocking as well. Automated or not, extra sets of contacts will provide stopping (safety) sections, and interlocked signals as well. IOW, you could make this crossing a showpiece of signalling technology... ;-)


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