American Flyer Reverse Loops

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Iron Horseman

Well-Known Member
I don't know how to look at a SCARM layout, but any two-rail model train reversing loop is going to be wired the same. Not all that hard. One needs to:
  • electrically isolate both rails of the loop from the rest of the layout
  • add a DPDT electrical switch (reversing switch) to the main line
  • add a DPDT electrical switch to the newly isolated reversing loop
To operate one sets the polarity with reversing loops DPDT to match the main for the side the train is going to enter from the main line. Run the train into the loop. While the train is in the loop flip the polarity of the mainline to match the exit of the reversing loop.
 

Iron Horseman

Well-Known Member
I am constructing an American Flyer layout I saw on SCARM and need help wiring the reverse loops. The SCARM file is AF.015.scarm. Can anyone show me how this layout is to be wired? Thanks.
Well I found an image of AF.015.

It does indeed have two reversing loops. That will require a DPDT switch for each one. Total of three. After thinking about it I would block it as the image below. The red bars are where you would have to use insulated rail joiners. As I recall standard AF track square tooth picks work for that. The blue section is one reversing loop, and the red is the other.

scarmS-scale.jpg
 

Thomas S.

New Member
Well I found an image of AF.015.

It does indeed have two reversing loops. That will require a DPDT switch for each one. Total of three. After thinking about it I would block it as the image below. The red bars are where you would have to use insulated rail joiners. As I recall standard AF track square tooth picks work for that. The blue section is one reversing loop, and the red is the other.

View attachment 146442
Thanks for the input. I am not sure which are the three DPDT switches you refer to. Can you please mark them? Do you need to throw switches only when the complete train is on the blue or reds track section? Any particular order in which to throw the switches? Are any jumper wires required? Is a separate terminal track needed for each track section red, blue and grey? Any other tips for construction would be appreciated. Again, thanks.
 

Iron Horseman

Well-Known Member
Thanks for the input. I am not sure which are the three DPDT switches you refer to. Can you please mark them? Do you need to throw switches only when the complete train is on the blue or reds track section? Any particular order in which to throw the switches? Are any jumper wires required? Is a separate terminal track needed for each track section red, blue and grey? Any other tips for construction would be appreciated. Again, thanks.
I'm sorry I assumed too much. Yes jumper wires are required. Here is the full wiring diagram below. DPDT means double pole double toggle electrical switch. I've added them in the wiring diagram. Yes you will need a terminal track in each of the three electrical sections. The jumper wires would of course go to that terminal clip rather than the generic place I showed on the diagram.

To operate ... Say the train is entering the blue section from the grey track right to left on the top track of the diagram. One would set DPDT REV #1 to match the polarity for DPDT MAIN. After the train enters the blue section of track and before it gets back to the grey one would change DPDT MAIN. That will change the polarity of the main to match the oncoming train. Similar process for the red reverse loop, only with DPDT REV #2.


scarmS-scale wiring.jpg
 

Thomas S.

New Member
Sorry you are dealing with a beginner. I think I am starting to understand that the DPDT is a switch positioned between the transformer and the track and has nothing to do with the track switches. The tech people at Lionel through me off when they told me the Fastrack switches were DPDT. The original SCARM plan shows just one reversing section (shown in dark grey). Could I get by with two DPDT switches in that case? Thanks for your help.
 

D. Soppy

New Member
If you follow the SCARM plan , you can get away with 2 DPDT switches. Make sure to put the insulated rail joiners where the grey's change color. If you use a DPDT ON-OFF-ON switch , you can put the switch in the center position and that will remove power to the track. It would be useful if you have to locos to run and want to use one for shunting while the other is connected to a train.
 

trailrider

Well-Known Member
The term "switches" when used in model railroading can cause confusion. For that reason, model railroaders refer to the pieces of track that change the direction of the train as "turnouts". Switches, as used here, refer to electrical devices, usually placed on control panels. A Double-Pole, Double Throw (DPDT) has six terminals, as shown in the diagram above. Wires from each side of the power pack connect to one set of terminals, with the pair of wires that cross connected to the other pair of terminals on the other end of the switch. The center terminals connect to each rail. The reason for the crossed connections, is so that the polarity is reversed when you throw the switch the other way. Toggle switches are most commonly used, although some slide switches may be available with the two pole setup. (Note: just to add to the confusion factor, prototype railroads refer to the direction-changing track pieces as "switches"!)
 

Iron Horseman

Well-Known Member
Sorry you are dealing with a beginner. I think I am starting to understand that the DPDT is a switch positioned between the transformer and the track and has nothing to do with the track switches. The tech people at Lionel through me off when they told me the Fastrack switches were DPDT. The original SCARM plan shows just one reversing section (shown in dark grey). Could I get by with two DPDT switches in that case?
Short answer is yes. You could isolate the dark grey section as a reversing loop.

Long explanation is an error on my part. The reason I did not choose that as the best option is because when I first looked at it, I thought that just to run a train around the inside loop one would have to be constantly flipping switches. But after your description, I can see that there would be one setting of the DPDT switches that would allow a train to run on that inside loop without constant attention. So double yes, you can do that with only two DPDT switches one for the dark grey section and one for the rest of the track.

edit. And actually there would be TWO settings of the DPDT switches that would allow running on the inside loop without constant switch flipping.
 

Suzie

Member
I would do it a little different

American Flyer.jpg

The small blue lines indicate where the outer rail should be isolated. If you switch turnouts 'A' and 'B' in conjunction with reversing the polarity of the reverse loop feed it will keep things very simple. With the switch in one position you will be able to run round the figure eight long run continuously, and in the other position run around the shorter low level loop.
 

Thomas S.

New Member
Now that the long holiday weekend is over I'm back to the design of the layout. Thanks to all who have responded, your comments have been very helpful.
 




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