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2 trains 1 track

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  • Member since
    June 2007
  • 14 posts
2 trains 1 track
Posted by joedor on Friday, February 15, 2008 10:41 AM

Can anyone help me figure out how to run 2 trains on 1 "O" gage fast track. The layout is 12x9 and is in a horse shoe shape. I understand the answer is in Dec. 04 issue of CCT but I really don't want to spend the money if one of you experts can help find a solution.

Thank you 

  • Member since
    November 2002
  • From: Colorado
  • 3,990 posts
Posted by fwright on Friday, February 15, 2008 11:36 AM

Some way, some how, you are probably going to need a book on wiring, or at least the cited article.  I don't know what the article says, so I can't tell you whether it's a good answer or not.

There are 2 basic approaches to controlling multiple locomotives on a single track.

The first is command control.  In 2 rail, most folks have gone to DCC for their command control system.  In 3 rail O, there are 2 competing, partially compatible systems - TMCC by Lionel, and DCS by MTH.  A command control system puts an individually addressable "decoder" in the locomotive.  The controller selects which locomotive(s) to talk to, and then sends commands to the selected locomotive, either via radio, or through the rails, or a combination.  The decoder knows when it is being addressed by the controller, and reacts to the commands.  The systems work well, and add sounds and other features to the locomotives.  But they do increase the cost of the equipped locomotives, and the controllers cost more than the traditional transformers.

The traditional system has no way to separate commands for one locomotive from another.  Without any other provision, the faster train will run into the slower because they cannot be controlled independently.  So a system of electrical blocks (electrically isolated sections of track) is created.  There is an electrical switch - usually a toggle switch - for each block that selects which transformer is connected to a given block.  If transformer A is going to control train 1, then the block switch where the train 1 is located is set to A.  As the train proceeds into the next block, the next block switch is set to A.  When the train has left a block behind, that block can be turned off, or set to B - the transformer that is being used to control train 2.  As the trains follow each other on the track, the block assignments are being continually updated so that transformer A always controls train 1, and transformer B always controls train 2.  The premise of the system is that you avoid getting both trains in the same block, because once you do, you have lost independent control.  Also, you must not assign both transformers to the same block.

In a closed loop of track, there must be at least 4 blocks for two trains to follow one another without stopping.

In 3 rail O, the blocks are usually created by using insulating track pins (or FastTrack equivalent) in the center rail at the block boundaries.  A separate feed wire is connected to the center rail of each block and the terminals of the block switch (SPDT or DPDT, center off highly recommended).  A wire is connected from each transformer (non-common terminal) to each side of the block switch.  The common terminals of the transformers are tied together, and connected directly to the outside rails.

Bottom line:  if you don't understand block wiring from an outline like mine, you need to switch to command locomotives and a command control system, or drop a few bucks on a book on model railroad wiring.  The book will have diagrams and much more detailed explanations than I can provide here on how to set up a block control system.  2 and 3 rail block control wiring use the same principles (except for reversing loops).  The difference in 3 rail is that the center rail is one conductor, and the 2 outer rails are the other. 

hope this helps

Fred W 

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