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Wiring at top of helix

Ken Bates
 

Hi,
I am building a new DCC layout with a double track helix from the fiddle/storage yard up to the running lines. The helix is climbing up clockwise and has the common on the outside, at the top of the helix I want to able to run trains clockwise (no problem, as the common will be on the outside on the layout as well), but anti-clockwise the feeds will be the opposite way round.
The idea is that at the top of the helix, a point (turnout) will give the option to go clockwise or anti-clockwise, what wiring is require to allow the anti-clockwise bit ?
Also, when running from the running lines to the fiddle/storage yard I want to be able to enter the helix from either direction, in this scenario, the anti-clockwise is okay, but the trains entering the helix that are running clockwise will have the feeds the opposite way round to the helix. Again what is required to enable this to happen ?
Any help please?

Paul O
 

Ken, to begin with, with DCC, usual terminology would be ‘left rail’ or ‘right rail’ as opposed to ‘common rail’.
That said, what you will need is a DCC reversing unit. 
Without a diagram of your track plan it’s impossible to say where your reverse loop would be.
 
Paul O

Carl
 

Hello Ken:

Sounds like you will have a Wye situation at the top of the helix. Will you be running two way traffic on the helix? Do the tracks at the bottom form a single line then spread to the fiddle yard?

I think I would make the fiddle yard and the helix one block and wire the layout with the Wye as the reversing section.

Can you share the layout plans?

Carl.

On 5/9/2020 10:20 AM, Ken Bates via groups.io wrote:
Hi,
I am building a new DCC layout with a double track helix from the fiddle/storage yard up to the running lines. The helix is climbing up clockwise and has the common on the outside, at the top of the helix I want to able to run trains clockwise (no problem, as the common will be on the outside on the layout as well), but anti-clockwise the feeds will be the opposite way round.
The idea is that at the top of the helix, a point (turnout) will give the option to go clockwise or anti-clockwise, what wiring is require to allow the anti-clockwise bit ?
Also, when running from the running lines to the fiddle/storage yard I want to be able to enter the helix from either direction, in this scenario, the anti-clockwise is okay, but the trains entering the helix that are running clockwise will have the feeds the opposite way round to the helix. Again what is required to enable this to happen ?
Any help please?

mgj21932
 

Ken,
Not sure I followed completely the description of your layout before and after the helix.  However, conceptually it seems to me that all you need is an AR circuit wired into the helix, with the helix isolated from the approaching (entering/exiting) segments.  Be sure your feeders to the helix are all wired from the power bus through the AR, and include feeders near the ends of the helix (where the short circuits that the AR will correct will be sensed).  
Unlike DC, the DCC system is not as "polarity" sensitive as your description suggests.  An AR circuit will automatically adjust the phase cycle of DCC to avoid the short that would otherwise occur.  Your trains should cross the gap into/from the helix indifferent to the change in phase cycle.  
Bill Demarest
mgj21932@... 

John Bishop
 

I'm not expert, but I think that a Frog Juicer for each turnout would do it. (That may be what "AR" refers to.) They are available from Tam Valley in units that will supply 1, 2 or 8 turnouts. 

John Bishop

On Saturday, May 9, 2020, 09:16:37 AM PDT, mgj21932 via groups.io <mgj21932@...> wrote:


Ken,
Not sure I followed completely the description of your layout before and after the helix.  However, conceptually it seems to me that all you need is an AR circuit wired into the helix, with the helix isolated from the approaching (entering/exiting) segments.  Be sure your feeders to the helix are all wired from the power bus through the AR, and include feeders near the ends of the helix (where the short circuits that the AR will correct will be sensed).  
Unlike DC, the DCC system is not as "polarity" sensitive as your description suggests.  An AR circuit will automatically adjust the phase cycle of DCC to avoid the short that would otherwise occur.  Your trains should cross the gap into/from the helix indifferent to the change in phase cycle.  
Bill Demarest
mgj21932@... 

mgj21932
 

I agree with the Frog Juicer suggestion from Tam Valley.
Whether placed on the Wyes of on the Helix, the key is to not have two segments of track wired with an AR (auto-reverser) circuit, adjacent to one another. There must be an “unswitched” segment — at least as long as your longest train (if using cars with metal wheels, the length of the loco if using only plastic wheeled cars) — between the AR-wired segments, or the ARs will fight with themselves as metal wheels cross the gap between segments, creating shorts on both sides, and triggering both ARs to try to switch phase polarity.
Bill Demarest

Ken Bates
 

Hi, I have added 4 photos of drawings into the album Kens Helix. Not sure if they are good enough for the purpose though.

It is a 2 track helix.

At the bottom, the down track just runs to the far end of the fiddle yard and the enters a fan of turnouts.

At the top of the helix on level 6 trains running anti-clockwise will take the turnout to do so, trains running clockwise will continue to level 7 to do so.
In both cases it is about 6 feet from there to the running lines. 

Trains joining the helix to go to the fiddle yard will arrive at level 7 from both anti-clockwise and clockwise directions. Again about 6 feet of track from the running lines.

Not sure if this makes it clearer.

Ken

wirefordcc
 

Hi Ken,

I don't think I see anything that complicates the wiring - meaning I don't see any reversing issues.

DCC doesn't require a concern for polarity for direction of travel like with DC.  A locomotive will go forward when commanded to do so regardless if which way it is pointing on the track.

Unless I'm missing something, just wire all outside rails to the same terminal on your booster, like rail "A" and that this follows through to the rest of your layout.  Rail "B' goes to the other rail.

Allan Gartner

Carl
 

Hello Ken:

I looked at your plans. It all looks like strictly one way traffic. Is there any route to run trains back on the same track?

Carl.


On 5/10/2020 8:42 AM, Ken Bates via groups.io wrote:
Hi, I have added 4 photos of drawings into the album Kens Helix. Not sure if they are good enough for the purpose though.

It is a 2 track helix.

At the bottom, the down track just runs to the far end of the fiddle yard and the enters a fan of turnouts.

At the top of the helix on level 6 trains running anti-clockwise will take the turnout to do so, trains running clockwise will continue to level 7 to do so.
In both cases it is about 6 feet from there to the running lines. 

Trains joining the helix to go to the fiddle yard will arrive at level 7 from both anti-clockwise and clockwise directions. Again about 6 feet of track from the running lines.

Not sure if this makes it clearer.

Ken

Ken Bates
 

Is there any route to run trains back on the same track?  No

Where I was worried, is at the top of the helix if a train is then going to run anti-clockwise once it passes the point on level 6 , the outside rail and inside rail are then opposite polarity to what they were on the helix, if this not a problem I shall stop worrying.... 

Same scenario for a train entering the helix from a clockwise direction, what was the outside rail on the running lines is now the inside rail on the helix.

Ken

wirefordcc
 

Hi Ken,

I didn't see the polarity reversal.  If you have one in your helix than you will likely need an auto reversing section, which could be in your helix, and an auto reversing unit.  

Allan Gartner

mgj21932
 

Ken the opposite phasing of DCC (while not as serious as the opposing polarity of DC) remains a problem, but is readily solved by wiring your feeders to the helix through an AutoReverse (AR) switch — a bit of magical circuitry that senses the short circuit created as the metal wheels of your loco cross the gap you will have at either end of the reversing segment and automatically switches the DCC phasing to eliminate the short before your in-line circuit breaker trips.  Very neat!  Be sure the length of the AR switched (or protected) track segment is as long as the longest train you plan to run (assuming metal wheels on your cars) and do not wire two AR segments adjacent to one another or they will with themselves until they melt down (at least figuratively). 
Bill Demarest
Mgj21932@...


On May 10, 2020, at 5:29 PM, wirefordcc <bigboy@...> wrote:

Hi Ken,

I didn't see the polarity reversal.  If you have one in your helix than you will likely need an auto reversing section, which could be in your helix, and an auto reversing unit.  

Allan Gartner

Ken Bates
 

Thanks to everyone for the advice, I believe I know what has to be done now.

just need to finish the rest of the helix, didn’t want to finish it and find I couldn’t do what I wanted to.

Ken