Re: Minimum length on Non-reversing segment


Think of any single loco as a pair of wires hovering, one over each rail, drooping to touch the rail at each point where a loco's wheels do.  In order for a short length between AR sections to do its job, it must be long enough to prevent the wire from bridging the two AR sections.  So before the wire enters the second AR it must leave the first AR.

Now generalize this.  The user must be aware of the longest electrically connected "thing" he runs.  For example if you run a dummy loco but wire its wheelsets to an adjacent engine, then that becomes the longest "loco".
That defines the shortest non reversing section between AR sections.
Hope this helps.

Sent from his Galaxy

-------- Original message --------
From: "mgj21932 via" <mgj21932@...>
Date: 2021-05-22 22:30 (GMT-05:00)
Subject: [w4dccqa] Minimum length on Non-reversing segment

I realize that we have addressed the question of Auto-Reverse (AR) segment wiring extensively in the past ( a discussion in which I even participated).  I understand that the track of an AR-wired segment cannot be electrically connected with another AR-wired segment, as the two will go to war with one another, switching back and forth until something blows.  And I also understand that for similar reasons, the minimum length of an AR-wired segment must be as long as the longest train that will run over it (or at least as long as the length of the train to the last car with either steel/metal wheels or an electrical pick-up that would cause a short if the "polarity" is not correct).   

What I am unclear about is the minimum length of the fixed (non-reversing) "polarity" segment that separates AR-wired segments.   I believe I recall a suggestion that the non-reversing segment be at least the length of a locomotive, but not sure why that would be required.     

In my case, my layout is a basic figure-8 pattern with two direction reversing segments, each wired with an AR circuit.   Problem is that one of those segments (about 6 feet long) was shorter than my nearly 7-foot long N&W passenger train (six 11+" MTH passenger cars plus a 13+" MTH N&W J loco).  In reconfiguring, I can lengthen the AR-wired segments to include portions of the figure 8 (assuring that both AR-wired segments are long enough), particularly if I do not have to be concerned that the length of the non-switching "polarity" segment have a substantial minimum length, e.g., not at least as long as my longest train.

I also assume that I can have more than one non-reversing segment separating AR-wired segments without any problems as long the "polarity" of all of the non-reversing segments is the same.   

Apologies if we have already covered this sufficiently in previous discussions; but I do not recall the definitive answer. 

Bill D
N&W Steam Only  

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