Double reversing loop wiring help needed

[wolfcarnahan]

Here's a link to my proprosed layout.  http://wolf.mind.net/files/layout.gif The loop near the bottom is for reversing in either direction. Of course it's a short circuit. What can I do to make it work?

Thanks,
Wolf

[simkon]

Isolate it and connect an automatic reversing unit.

[Nathan]

Make sure the longest train will fit within the reversing area if it is a passenger train with lighting or the caboose on a freight has lighting.

[Atlantic Central]

wolfcarnahan - Are you using DC or DCC?

simkon - rather presumptuous to assume the OP is using DCC.

Nathan - ALL reversing sections, DC or DCC, should be longer than the longest train even if lighted caboose or tail cars are not used because metal wheels will short the reversing section as they cross the gaps.

Sheldon

[wolfcarnahan]

I'm using DC.

[Joe Satnik]

Dear Wolfy,

There are all kinds of things to be aware of on a reverse loop layout.  (Building and operating.)

GAP PLACEMENT:

You can start by putting gaps in both rails on or just beyond the "main route" end and "divergent route" end of the furthest west and furthest east turnouts in your diagram.  (4 tracks, 8 rails with 8 gaps total.) 

(Note: the "single" route at the other end of the turnout is called the "points" end.)

These 8 gaps separate your layout into two electrical areas:  1) The "Northern Track" area, including the east and west turnouts, and 2) the "Southern Loops" area, which is everything else.     

The "Southern Loops" area would be hooked directly to the power pack. 

A DPDT switch (Double Pole Double Throw) switch wired in a reversing pattern would be connected between the power pack and The "Northern Track" area.

Back of DPDT switch:

1 2 3
4 5 6

Power pack + to 1 and 6
Power pack - to 4 and 3
Northern Track north rail to 2
Northern Track south rail to 5 

Hope this helps.

Sincerely,

Joe Satnik

[Joe Satnik]

Dear Wolfy,

Hold off, I have to think some more on the gaps and reverse wiring.

Joe

 

[Jim Banner]

To add a diagram to Joe's excellent explanation, may I offer the following:



The gaps at at the red marks.  This leaves the maximum possible length of reversing loop, about 10 feet long.  If you are interested, I can give you a diagram of how to add an indicator light to show if the DPDT switch is set correctly when you are approaching the gaps.

Note:  diagram updated after Joe Satnik point out an error in it.

Jim

[Joe Satnik]

Nice diagram, Jim,

Thanks for the correction to the "Northern Track" area. 

Dear Wolfy, I'm still hashing through the DC switching and gaps.  Again, hold off till I put some more thought into it.

Sincerely,

Joe Satnik

Edit: Remove my notice and acknowledge Jim's correction of diagram. 

[Joe Satnik]

Dear Wolfy,

Best I can do short notice.   

I'm way open here to other ideas, criticism or corrections.

You will need 2 DPDT switches fed by the power pack and wired for reversal. 

The label on one reads "Northern Track CCW vs. CW". 

The other reads "Southern Loops CCW vs. CW".

That be clockwise vs. counter-clockwise.

Can you run with that, Jim?

Detail of wiring later, similar to single DPDT description.

Sincerely,

Joe Satnik
   

[Jim Banner]

ARRGH!!  Joe, you are of course correct.  I thought I had connected the blue wires to the northern track, but tracing it around, they were in fact on the southern track side of the turnout.  Double Arrgh!  The corrected diagram is shown above.

Using two DPDT switches and ignoring the reversing switch on your power pack is a fancier way to go.  If you intend to stay with dc, you will probably want to go that way.  Back when I had my layout wired for running one train at a time on dc, I used a single reversing switch, similar to that shown, mounted on the table.  When I was on the track controlled by the table mounted reversing switch, and I needed to match polarity at a gap, I would throw both the table mounted reversing switch and the reversing switch on the power pack, both at the same time.  This double reversal kept the train going in the same direction but would match polarity before I crossed the gaps.  If I was not reversing direction, this maneuver was unnecessary and I could use just the reversing switch on the power pack.  Later, when I went to a walk around control, a reversing switch on the table and one on the walkaround was a nuisance so I built a walkaround that had two reversing switches on it, one for the mainline and the other for the reversing loops.

I tell you all this just to explain some of the alternatives that are available when you are running on dc.  If you plan to eventually go to DCC, I would stick with the simplest possible system and put the cost of an extra switch toward the cost of DCC.  With DCC, the single switch would work the same, except you would not have to change direction on the throttle.  Or you could replace the single switch with an automatic reversing module which works with DCC but not dc.

Jim

[jward]

there is a much simpler solution to the problem.

by using a bridge rectifier rated at least 3 amps, you can eliminate the dpdt switch and most of the complexity of operation, the trade of is that your reversing section can only be travelled in one direction.

on your layout, i would make the cutoff route through the center of the layout my reversing section. gap both rails at the entrance and exit switches for this track. this is exactly the same location as the diagram shows. you will also need to gap the curved route on the circle at the bottom. i'd gap both rails on the curved routes just beyond the switches themselves.

the ac terminals of the bridge rectifier go to the power pack, or block switches if you have them. the dc terminals are connected directly to the rails of the reversing section.

to operate the reversing section, enter through the designated entry switch. continue to run your train, and flip the reverse on your power pack. the rectifier keeps the train traveling through the reversing section, in the same direction. when you get to the exit switch, your polarity on the main track is already set and you exit with no problems.

i will let somebody who is adept at drawing come up with an illustration.....

[Joe Satnik]

Dear Jeff,

You could, in simplifying to one direction only on a reverse loop, install a spring loaded turnout, and not have to manually throw it.

However, I'm guessing that Wolfy might want all the routes and directions possible, so I will call out 2 DPDT reversing switches.

In my 2 DPDT scheme, I count 8 ways to leave and get back to the "Northern Route".   If you want to stay in the small circle of the southern loops, that's 2 more routes, if you count both CCW and CW directions around the circle.



Two  DPDT (Double Pole Double Throw) switches wired in a reversing pattern would be connected between the power pack and their respective track areas. 

Back of DPDT switch for the "Northern Track" area. 

1 2 3
4 5 6

Power pack + to 1 and 6
Power pack - to 4 and 3
Northern Track north rail to 2
Northern Track south rail to 5

Back of DPDT switch for the "Southern Loop" area. 

1 2 3
4 5 6

Power pack + to 1 and 6
Power pack - to 4 and 3
Southern Loop north rail to 2
Southern Loop south rail to 5

For testing purposes, put your power pack in the forward direction and the Northern Track reversing switch in the CW position.   Place a loco on the Northern Track facing the CW direction.  Give just enough juice to see that the loco is going forward.  If not, swap the 2 wires by sending 5 to the north rail and 2 to the south rail.   After swap, re-test.     

Again, with your power pack in the forward direction,  put the Southern Loop reversing switch in the CW position.   Place a loco on the Southern Loop facing the CW direction.  Give just enough juice to see that the loco is going forward.  If not, swap the 2 wires by sending 5 to the north rail and 2 to the south rail.  After swap, re-test. 

One Atlas #210 "Twin" electrical switch (reversing built-in) will take the place of both of the above DPDT reversing switches.  It may be cheaper than buying two DPDT switches.... 

Hope this helps. 

Sincerely,

Joe Satnik   

[Joe Satnik]

Wunna dese:



Atlas 210 Twin MSRP $9.75

[wolfcarnahan]

  :)You guys are awesome!! Thank you. All is well.

Wolf