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This information is for Pecos ElectroFrog crossover, which Peco calls a Scissors Crossing. A double crossover has eight frogs. Four of them have polarity controlled by the points. The other four (2 sharp and 2 shallow) have track power feeders connected to them - these are the ones whose polarity you have to be concerned about. There are several combinations of how the polarity might come to the ends of the crossover. If using DC analog train control, youll have to handle all this in the traditional way - with toggle switches. If using DCC, you can use a Digitrax Auto Reverser, one output of a Digitrax PM42, or a set of external contacts. This requires polarity to come into the crossover in a specific way and is what the rest of this dialog will address. First well show you how it has to be, then well discuss what you have to do to set your layout up for this. Iillustration 1 below shows how polarity must come into the crossover in parallel. |
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In Illustration 2, notice that
the rails connecting to the crossovers outside stock rails are
of different polarity the top one red and the bottom one green.
Also note that the rails connecting to the sharp (blue) frog rails are
different polarities. Connect one sharp frog feeder to one output of
the auto-reverser and the other sharp frog to the other output of the
auto-reverser. The shallow (yellow) frog feeders are connected directly
to track power the upper one to red polarity, the lower one to
green polarity. |
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If using external contacts, instead
of an auto-reverser, you have to realize that the contacts will be connected
to only one throw bar, and that all throw bars must be operated as a
set that is, all four turnouts thrown for crossing over, or all
four turnouts closed for going straight through. Of course, since a
train cant cross over at the same time a train is going straight,
theres no reason to not set your crossover up so all turnouts
work together anyway. |
Thats all there is to making a Peco crossover work. If the polarity doesnt come into the crossover as shown in Illustration 2 above, you have a reverse section somewhere on the layout that hasnt been resolved. To fix this, you need to go back on that track with the wrong polarity and install a reverse section so that the polarity comes into the crossover correctly. Regardless of what the situation is, the polarity must match as shown in Illustration 2. Note that it doesnt matter what the polarity is as long as it matches in all directions. Once it matches, resolve the frog polarity as described above. |