A solution for a Reversing Section shorter than the whole train.

By Don Vollrath. Copied from the NCE list at Yahoo Groups 19 Aug 06.

--- In NCE-DCC@yahoogroups.com, "denlippert" <denlippert@...> wrote: Impossible. Any train longer than 4 feet or so (two E-8's and 2-3 passenger cars) will be bridging from one "constant polarity" section (the mainline) to another (the station) which are out-of-phase.

Gents,

The difference between the Loy's ARSC (and my STRC) from a conventional auto-reverser is the presence of a sensing 'portal'

that can tell the difference between a loco and other cars.

The portals are a short section of insulated track, one at each entrance to the center reversing track. It detects when both rails become energized by a truck with both sides of its axle wheels being tied to other wheels on electrified track. (Think all-wheel pick-up of a loco.) This is what flips the center reversing section of track to match the main track polarity at that end. (The active portal does end up getting powered so there is no dead track.) A passenger car pick-up truck typically has only one side or the other with electrified wheels. [The other rail polarity for lighting is picked up by the truck at the opposite end of the car.] If the portal is only as long as the typical three axle truck only one portal rail will become energized at any given time as a power pick-up truck passes through. It does not power both rails and causes no reverser action.

So that is part of the mystery. The other half to improve performance, is to make sure that rail gaps of the portal are wide enough so that the flange of a non-powered steel wheel cannot inadvertently bridge a gap, even on curved track.

The center reversing section needs to be only as long as the longest loco consist.

Yes, lights in trailing passenger cars will blink. Yes, the passenger cars must NOT have all wheel pick-up. Yes, it may not work with old steam locos with staggered pick-up. So there are some limitations.

See the full report at

http://groups.yahoo.com/group/WiringForDCC/files/ Look for Short Track Reverser.

When you really need it...It works.

DonV