#### Reverse Loop Finder

Don Vollrath

Tom,
The problem occurs because locos in particular, as well as many passenger cars with lights will have electrical connections between the wheels and axles on the same side of the rails on the same or multiple trucks. This is done to aid power pick-up. When one of these multi-axle units spans across the gap where opposite voltage appears, it creates a short circuit.
DonV

Carl

Hi Gang:

Working on two layouts that are "around the room" style I like to pick a point in the center. The reversing loops are anywhere direction switches from CW to CCW. The HO layout I help with was figured differently, it started as a "dog bone" with two cross overs that reversed direction. Then they connected the ends of the "dog bone" forming a third reversing section. If we had wired it thinking from the center, only the "dog bone" loops would have been reversing.

Plus, you don't want a long train or two shorter trains crossing the gaps at the same time.

A couple of years ago this group was presented with a layout with reversing questions and from the center point worked for me.

Carl.

On 3/4/2019 4:02 PM, Tom G. via Groups.Io wrote:
David,

Thank you, I understand. I understand the reason the whole train (or at least all powered sections need to be on one side as well. Thank you!

Thanks.
Tom

On Mar 4, 2019, at 3:54 PM, David Klemm <davidklemm7511@...> wrote:

Tom,

Best to draw it out so you can see it. First yes you double gap both ends. If you draw the rails on paper with one being black and the other rail say red. When the red meets up with a black you have a short. Thus the need for a double gap. But an engine or lighted passenger car is not on one side and then magically on the other side of the gap. You have for a period of time one truck on one side and the other truck on the other side.

So you need a way to flip polarity very fast.

More complicated is if your reverse loop isn’t long enough. But that is for later after you get the above concept.

David Klemm
Xs Max

From: w4dccqa@groups.io on behalf of Tom G. via Groups.Io <tjg81296@...>
Sent: Monday, March 4, 2019 14:46
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Reverse Loop Finder

Thanks for the tip!

Can someone explain why my thinking is incorrect? If you gap the rails into the loop and apply bus power to both sides, separately, why does it matter if there’s a reverse loop? Won’t the train just get power and keep trucking?

Thanks.
Tom

On Mar 4, 2019, at 3:35 PM, rhemker <rhemker@...> wrote:

Just placed my simple method of finding reverse loops in the Photos section. I find a truck and place a small piece of blue tape on one side of the truck. Then, I place the truck on the track with the blue tape on the north rail and run it around the layout. If you find the blue tape winds up on a south rail then you've discovered a reverse loop. This works for simple reverse loops but not sure if it will work on complicated reverse loops within loops. Can't remember where I got this tip but, be sure I did not discover it.

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Tom G.

David,

Thank you, I understand. I understand the reason the whole train (or at least all powered sections need to be on one side as well. Thank you!

Thanks.
Tom

On Mar 4, 2019, at 3:54 PM, David Klemm <davidklemm7511@...> wrote:

Tom,

Best to draw it out so you can see it. First yes you double gap both ends. If you draw the rails on paper with one being black and the other rail say red. When the red meets up with a black you have a short. Thus the need for a double gap. But an engine or lighted passenger car is not on one side and then magically on the other side of the gap. You have for a period of time one truck on one side and the other truck on the other side.

So you need a way to flip polarity very fast.

More complicated is if your reverse loop isn’t long enough. But that is for later after you get the above concept.

David Klemm
Xs Max

From: w4dccqa@groups.io on behalf of Tom G. via Groups.Io <tjg81296@...>
Sent: Monday, March 4, 2019 14:46
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Reverse Loop Finder

Thanks for the tip!

Can someone explain why my thinking is incorrect? If you gap the rails into the loop and apply bus power to both sides, separately, why does it matter if there’s a reverse loop? Won’t the train just get power and keep trucking?

Thanks.
Tom

On Mar 4, 2019, at 3:35 PM, rhemker <rhemker@...> wrote:

Just placed my simple method of finding reverse loops in the Photos section. I find a truck and place a small piece of blue tape on one side of the truck. Then, I place the truck on the track with the blue tape on the north rail and run it around the layout. If you find the blue tape winds up on a south rail then you've discovered a reverse loop. This works for simple reverse loops but not sure if it will work on complicated reverse loops within loops. Can't remember where I got this tip but, be sure I did not discover it.

rhemker

Tom,

My tip will identify the reverse loop and when the positive north rail meets the the negative south rail, a short will occur.

Have a great day

Rick Hemker

From: w4dccqa@groups.io <w4dccqa@groups.io> on behalf of Tom G. via Groups.Io <tjg81296@...>
Sent: Monday, March 4, 2019 2:46 PM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Reverse Loop Finder

Thanks for the tip!

Can someone explain why my thinking is incorrect? If you gap the rails into the loop and apply bus power to both sides, separately, why does it matter if there’s a reverse loop? Won’t the train just get power and keep trucking?

Thanks.
Tom

On Mar 4, 2019, at 3:35 PM, rhemker <rhemker@...> wrote:

Just placed my simple method of finding reverse loops in the Photos section. I find a truck and place a small piece of blue tape on one side of the truck. Then, I place the truck on the track with the blue tape on the north rail and run it around the layout. If you find the blue tape winds up on a south rail then you've discovered a reverse loop. This works for simple reverse loops but not sure if it will work on complicated reverse loops within loops. Can't remember where I got this tip but, be sure I did not discover it.

David Klemm

Tom,

Best to draw it out so you can see it. First yes you double gap both ends. If you draw the rails on paper with one being black and the other rail say red. When the red meets up with a black you have a short. Thus the need for a double gap. But an engine or lighted passenger car is not on one side and then magically on the other side of the gap. You have for a period of time one truck on one side and the other truck on the other side.

So you need a way to flip polarity very fast.

More complicated is if your reverse loop isn’t long enough. But that is for later after you get the above concept.

David Klemm
Xs Max

From: w4dccqa@groups.io on behalf of Tom G. via Groups.Io <tjg81296@...>
Sent: Monday, March 4, 2019 14:46
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Reverse Loop Finder

Thanks for the tip!

Can someone explain why my thinking is incorrect? If you gap the rails into the loop and apply bus power to both sides, separately, why does it matter if there’s a reverse loop? Won’t the train just get power and keep trucking?

Thanks.
Tom

On Mar 4, 2019, at 3:35 PM, rhemker <rhemker@...> wrote:

Just placed my simple method of finding reverse loops in the Photos section. I find a truck and place a small piece of blue tape on one side of the truck. Then, I place the truck on the track with the blue tape on the north rail and run it around the layout. If you find the blue tape winds up on a south rail then you've discovered a reverse loop. This works for simple reverse loops but not sure if it will work on complicated reverse loops within loops. Can't remember where I got this tip but, be sure I did not discover it.

Tom G.

Thanks for the tip!

Can someone explain why my thinking is incorrect? If you gap the rails into the loop and apply bus power to both sides, separately, why does it matter if there’s a reverse loop? Won’t the train just get power and keep trucking?

Thanks.
Tom

On Mar 4, 2019, at 3:35 PM, rhemker <rhemker@...> wrote:

Just placed my simple method of finding reverse loops in the Photos section. I find a truck and place a small piece of blue tape on one side of the truck. Then, I place the truck on the track with the blue tape on the north rail and run it around the layout. If you find the blue tape winds up on a south rail then you've discovered a reverse loop. This works for simple reverse loops but not sure if it will work on complicated reverse loops within loops. Can't remember where I got this tip but, be sure I did not discover it.

rhemker

Just placed my simple method of finding reverse loops in the Photos section. I find a truck and place a small piece of blue tape on one side of the truck. Then, I place the truck on the track with the blue tape on the north rail and run it around the layout. If you find the blue tape winds up on a south rail then you've discovered a reverse loop. This works for simple reverse loops but not sure if it will work on complicated reverse loops within loops. Can't remember where I got this tip but, be sure I did not discover it.