Re: Shinohara DCC Friendly 3 way turnout wiring

John Cahill

Am I correct in assuming a Hex Frog Juicer would do away with need for electro-mechanical switching?

Best Regards,

On 27 Jun 2013, at 05:54, cascade fun <cascadefun@...> wrote:

Thanks Mark,

You are right, I hunted every DCC wiring site I could find, and no one has anything up about 3 way turnouts. Many thanks for the info and for pointing out the handy link.

Jim S.

To: WiringForDCC@...
From: gurriesm@...
Date: Wed, 26 Jun 2013 20:29:23 -0700
Subject: Re: [WiringForDCC] Shinohara DCC Friendly 3 way turnout wiring

All 3 way turnout require TWO tortoise machines. A three way turnout is a left hand and a right hand turnout stacked on top of each other. So there are actually two turnouts with each tortoise controlling one of the two turnouts and hence the turnout's coresponding frog. The frog the given tortoise controls is related to the two track paths the given tortoise sets and that is still true. However with a 3 way, there is a 3rd frog introduced that is the result of the overlap and that is where the confusion comes into play.

First some mechanical background considerations of 3 way turnouts. There are two types of 3 way turnouts.

1) Symmetric 3-way. The symmetric 3-way have overlapping point rails such that one set of point rails will FORCIBLY move the other set. Unfortunately the mechanical interlocking of the symmetric requires control logic (control interlocking) to be implemented to throw BOTH tortoise at the SAME TIME to set up the desired route. The advantage of the symmetric 3-way is all 3 diverging track paths are about the same length from the start of the turnout. In other words there is no impact on track length that feeds into the 3-way.

2) Asymmetric 3-way. Asymmetric 3-way allow the two sets of point rail to move independently of the other. There is no mechanical interlocking allowing you to throw the two sets of point rails at DIFFERENT TIMES to get the desired path or route. Hence the asymmetric is easier to install from a control point of view. The down side of the asymmetric is the 3-way turnout is physically longer (less compact) than symmetric -3way and two of the 3 track paths will have a long path through the switch than the other. Stated another way, two track paths will be a bit shorter than the first if one was building yard tracks of equal length.

Regardless of the Symmetric or Asymmetric, there is a dominate route controlled by the 1st set of point rails. Since most (all?) 3-ways are right hand dominant, the 1st point rail controls the 1st two frogs (center frog and right frog as if they are one frog. The last or left hand frog can be wired one of two ways. Both methods are valid and are shown with pictures here.

What is the difference? Preservation of PowerRouting on the last frog.

1) Simple (Independent Left and Right hand Frog power)

Scroll down to see the 1ST diagram. Best Solution for DCC. Here the last (Left hand) frog is treated as if it is part of the left hand turnout just like a normal left hand turnout.

2) Interlock (Power Routed Frog power).

Scroll down to see the 2ND diagram. Here the last (left hand) frog power is dominated by the right hand turnout path. Best Solution for DC users who need full to preserve power routing through the entire turnout and on to the 3 tracks the feed into the 3-way. All 3 frogs are power routed which mean there is only 1 of the 3 possible paths that is fully powered. The power matches the path that is set. Power Routing past the turnout has no real advantage for DCC users. There is no need to kill track power to stop a engine on the non selected track.

The common requirement is that all converging rails feeding into the Left hand and right hand frogs must be fully insulated from the frog.

I think you have point out a missing topic in the Wiring for DCC website that we will fix (at least I could not find it myself and that just may be me...).

On Jun 25, 2013, at 1:32 PM, amtk507 wrote:

Anyone have a wiring diagram of how they powered the frogs for a 3 way turnout using the tortoise switch machine? Your help will be appreciated. Thanks.


Best Regards,

Mark Gurries

Electrical Engineer

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