Just curious, how does two rail power work? Is one rail still insulated? Such as in HO or American Flyer. Thanks, Jake
PS. Also, why are some Lionel trains DC?
Two rail power comes in two flavors, AC (like Flyer), and DC, like HO and N, and two rail O. Yes, the rails are insulated. Under AC, One rail is "hot", the other is the "return". On DC, one is positive, the other negative.
Yes, Lionel made some lower end sets in the seventies that were three rail, DC powered. You can find instructions on the Lionel web site on procedures to modify these sets to run on AC power (bridge rectifier and an "e" unit).
The two rails are insulated from each other. One rail may be connected to metal ties; but that doesn't matter.
American Flyer and Maerklin use AC with two rails. An American Flyer reversing unit (not "e-unit") works very much the same as Lionel's, but is smaller, which can be handy for cramming one into a small O-scale locomotive. The scale operators use DC on their two rails and control direction with the DC polarity, rather than stepping an e-unit. The right-hand rail is positive and the left-hand negative when going forward.
Lionel briefly used DC to be able to control direction with polarity and get rid of the e-unit. An interesting difference between two-rail and three-rail DC is that, if you lift a two-rail DC locomotive off the track, turn it around, and put it back, it will continue in the same direction as before, since you have not only swapped ends but also reversed the motor connections by turning it around. A three-rail locomotive will go the other way, since swapping ends does not change the motor connections. This would make it difficult to run three-rail double headers unless both locomotives faced the same way.
Bob Nelson
Bob: I think Marklin uses three "rail" track -- the center "rail" is a succession of almost invisible "studs" that stick up from the roadbed which looks something like FasTrack, but with studs rather than a center rail. A sliding shoe under the engine picks up current from the studs, just as rollers do on regular three-rail equipment. They introduced this system in (I believe) 1953, and it soon replaced their regular three-rail system. They also offer similar equipment in the usual 2-rail DC system under a different brand (name of which escapes me at the moment).
I sorta expect the next big track development in our O gauge AC railroading to be stud-rail trackage.
You're right. I don't know how I got that wrong.
I'm skeptical that we'll see "pukos" ("punktkontakten") in O. I would bet on something like Dave Vergun's system with battery power and radio control.
Just a note.Be careful putting Lionel or other cars with metal wheels on two-rail track.The wheels on two-rail need to be insulated from each other. I know most of us know this but for the unexperienced a heads up.
Ed
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