Reverse loop operations??

Discussion in 'G / O / S Scale Model Trains' started by hans911, Feb 8, 2006.

  1. hans911

    hans911 New Member

    Being a newbie this may be obvious, but here we go.....

    The potential G scale outdoor layout I have in mind is a dogbone shape, two loops connected in the center by one long straight. I understand I need to install the reversing loop units by LGB or Aristo. However in the online instructions they state that a train needs to be stopped in each loop and/or the controller needs to be switched to the other direction each time the train travels through the loop.

    1) Is this correct or am I misunderstanding it?

    2) If so is there a way to run the train continuosly with standing by the controller to manually do this manueuver each and every time the train travels through a reverse loop? [​IMG]

    Thank you for all your help again in advance!
  2. Philinbos

    Philinbos Member

    I wondered about this for a couple of years - Hope you get an answer!
  3. 60103

    60103 Pooh Bah

    Unless you use DCC (q.v.), you will need to do the reversing of the main track each time.
    I don't know the reversing modules you mention.
    If all you have are the 2 loops and the straight, you could hook a sensor into each reverse loop that would:
    -change the switch
    -change the direction of the single track
    -change the other switch.
    This would mean that you would go around the reverse loops in the same direction each time. It's a bit simpler than having a pair of sensors in each loop.
    Don't know enough about G to know what sensors/contacts are available.
  4. pgandw

    pgandw Active Member

    David is correct in his outline. Again, assuming DC, the gist of the problem is that the direction (polarity) of the main line must be changed while the train is COMPLETELY electrically isolated in the reversing section so that when the train comes back onto the main line the polarity is correct for its now opposite direction. There should be a total of 3 direction toggles - one for each loop, and one for the "main" straight section. You cannot use the direction switch on your power pack.

    Because of the need for the train to be totally in the reversing section when the polarity is changed, a relay attached to the turnout will not suffice. As David said, you need some sort of detection system to trip the relay. And if you are using both directions on the reversing loop, you will need 2 sensors - unless your train will never be longer than half the reversing loop.

    Given the headaches of reliable electrical contact, even for G, in an outdoor environment, getting the sensor and relay to work reliably every time with no false positives is going to be a challenge. Some of the more sensitive sensors like an update of the old Twin-T may throw the relay when some foreign objects - maybe wet leaves? - fall across the track. This you do not want! Also, keeping the sensor and relay working in the more extreme weather will require careful planning.

    This type of layout has always been the bane of 2 rail wiring, and where 3 rail or live overhead looks tempting. 3 rail or live overhead has no polarity issues through reversing loops. But that's a discussion for another day.

    There are 2 alternatives to get things running continuously without a detection and relay system or manual throwing of direction at each loop:

    1) double track the straight section. That way the train only reverses when you choose to. Then you only have to change the main direction switch when you actually reverse. Requires 2 more turnouts and extra track, though.

    2) Switch to radio control and battery power. Now, you are independent of track wiring and cleaning headaches. A little spendy, though.

    Some of the DCC auto reversers may work for conventional DC. Check Tony's Trains web sites for details.

    yours in reversing
  5. hans911

    hans911 New Member

    Thanks for the advice! Question 2

    Thanks for the advice.

    What, however, do you mean by "double track". Is this simply making the layout into a loop instead of the single out and back with loops at the ends?

    I have a bi-level yard and the section available for the railroad is a 4'x60+ ft strip raised approx. 4 ft from the ground level. I could I suppose lay the returning track line parrellel to the out track line. Was trying to not make it look too busy though with the original 'dog bone reverse loop' design.
  6. pgandw

    pgandw Active Member

    I understand your reluctance to add track in an outdoor G setting. However, you either need to set up an automatic system to handle the reverse loops, or get away from reverse loops in normal operation to get hands-off continuous operation. That is a limitation of 2 rail DC wiring.

    I did a quick check - none of the DCC auto-reversers can be used with DC. So unless you are switching to DCC or battery power, you have to either manually switch the "main" direction switch while the train is in the reversing loop, or build your own auto-reversing system.

    Which gets back to getting some sort of train sensor at each reverse loop. I'm sure there are some listed in Walters, at least the HO catalog. Which will work well in an outdoor G setting is another matter. Look for high current capacity, ability to weather-proof the installation, and ability to work in most lighting situations.

    Optical detectors probably will not work in your case. Using KISS, the easiest might be magnetic reed switches mounted on a structure or pole close to the track. A magnet mounted on your locomotives should be able to trip the reed switch reliably (after some fiddling). The reed switch would then be used to actuate a latching 4PDT relay. Two poles are needed to reverse the main (straight) track polarity. The other 2 poles are needed to throw the switch machine of the reverse loop. For this scheme you, need a stall motor switch machine that uses continuous power. To operate a twin coil switch machine, you will need an intermediate momentary actuated by primary relay to provide momentary power to the switch machine or a set of contacts to achieve the same result.

    Reed switches should be set up to work on one side of the locomotive only so you can put a reed switch near each end of the reverse loop for bi-directional operation. You only want the far reed switch to actuate as you enter the reverse loop.

    If you don't understand any of this electrical stuff, it's probably not a good idea to try it. I don't model in G so I don't know what the G manufacturers put out for this situation. However, the 2 rail DC wiring principles are the same, regardless of scale.

    Hope this helps
  7. hans911

    hans911 New Member

    Thanks again Fred for all the great input. After reading your advice and a quick trip to the local train store I am convinced I should do away with the reverse loop design and redesign to a standard loop with no reversing.

    So what's another 50 ft of track? Just an opportunity to build a tunnel and/or bridges to make it interesting.

    Thanks again. The advice found on this forum is priceless.
  8. CaseyJonesII

    CaseyJonesII New Member

    Reverse Loop Answer


    I had reverse loops on both ends of my G empire. as the train went through one loop, it aligned the switch for the second loop. I have wiring diagrams. It is very simple to wire and maintain and it worked great. My new layout in our new home (indoors) is continuos because of the arrangement. I think you should have reverse loops. I could send you the diagrams if you wish

  9. Philinbos

    Philinbos Member

    It would be great to see the diagram and the idenity of the switches you used! Thanks in advance...
  10. CaseyJonesII

    CaseyJonesII New Member

    Lgb Epl Reverse

    Give me your email address and I will send the sketches. As I said I use EPL technology and auto switches on both loops so I can set the direction. I have a good three pags of explanation and sevral wiring diagrams. It is so easy to wire and maintain. The same technology is applied to the wye.

  11. CaseyJonesII

    CaseyJonesII New Member

    Block Signal Wiring

    For those of you with indoor layouts, I also use MTH and Lionel #153 block signals along with LGB EPl technology and when my switches are thrown, the block signal turns red and green when staright. I also use signals to show a block is occupied and when the train leaves that block, the light goes back to red. It's taken me awhile to wire my layout, but the finished effect leaves visitors spellbound, especially when we stand at Paradise station and the block signal changes to green and we can hear the train in the distance.
  12. Philinbos

    Philinbos Member

  13. camelothouse

    camelothouse New Member

    Roy Cooper


    If it's not inconvenient, could you please e-mail me the your diagram for reverse loops. I also have a G scale outdoor layout with the same problems.

    Thank you.
    Roy Cooper, Florida

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