Quick Newbee Question....turn around loop.

[Anonymous]

Me and my boys started a HO train set.

First it was a Life Like Kit and 4x8 layout.  To small.  Built another 4x8 bench and expanding.  I'm now completeing a turn around loop...maybe I'll get it done tonight and answer my own question:

How does it work if the outside rail becomes the inside rail during a turn around loop?  I mean electrically, isn't there a problem with + and - issues? 

As mentioned, maybe I'll be able to hook it up myself and try it and see what happens when the rails are crossed so to speak.

My first post here...I'm an R/C plane guy by nature.

Coo

[ndbprr]

You will get more answers on the model railroading forum but yes you will have a dead short.  There are two ways to solve your problem. The traditional way is to isolate the return loop as a separate block with its own toggle switch (DPDT).  When the train enters tat block you can then reverse the main section sith another toggle switch (DPDT).  That alligns the power for where the opposite polarities would be are now the same.  Today there are much more sophisticated electronic devices that can do this for you but that will get you through the basic construction phase at the cheapest cost.  Any decent hobby shop should have a variety of devices in all price ranges from aboiut $25.00 and up.

[Anonymous]

Wow...thanx for the quick reply.

I'm familiar with these forems from my R/C plane hobby.  A great place to ask questions and get answers...looks like this is a similiar community for HO train sets.  You mention "model railroading forum"...am I in the wrong forum for my type questions?

When I'm at the LHS today getting a couple things I need to finish the turn-around loop, I'll ask them what is needed.

You are saying the best way is to wire up the loop and the main line as two seperate systems.  While the train goes onto the turn-around loop and runs around that 8-10 foot of track, I switch the polarity of the main line.  By the time the train runs off the turn-around loop, the main line will be "reversed" to match the new direction designated by the turn around loop.  Sounds like it makes sense.  I hope it's not to involved.  I mean it wont be to hard to wire it up with the proper switches and all, but hope the boys grasp the concept.

I'm taking for granted to seperate the two elements, I use the little plastic rail joiners at each "end" of the turn around loop so the are insulated from each other.

Can I ask another question?  As a kid I remember little spring steel wires in a section of track to "un-couple" cars.  We had them placed right after a switch on a dead end spur.  When backing over it, it would uncouple the cars.  Slam on the breaks at the right point over this "decoupler" and the cars would slide away from the engine.  The little spring steel wires would "open" the cars couplers when going backward, but not forward.  I could not find such a thing at the LHS.  Is it still the simple easy way to uncouple cars and "drop off" a couple cars at dead end spurs?  The LHS lady was trying to sell me some involved electronic/magnetic system.  Trying to keep it simple.

Thanks for the reply and advice.

CooHead

[drafterdude]

CooHead

Go to the NMRA.org site and click on the beginners section then the wiring link and scroll down to the section on reverse loops for an explanation of how to do this.

Dale

[Anonymous]

Will do.

Thanks for the link and advice.  Seems like there is a good croud here to help us newbees.

Coo

[Anonymous]

Thanks guys.

I did go the .org web site and learned a bit.  I did buy a package of four DPDT switches at the LHS today at lunch.

Am I guessing this right:

I put the main layout on one DPDT switch and the 8'-10' worth of turn around track on another DPDT switch.  When it's on the turn around, I flip the switch that controls the main layout.  Once the train goes onto the main layout, I'd flip the switch controlling the turnaround so it's ready for the next time I run the train onto that turn-around section?  Of coarse I have the turn around track section insulated from the entire layout.

The next question for me is how to wire it all up.  There was a breif schematic on the .org website that shows the bottom of the switch.  Not much explination tho.

The switches I bought are Miniatronic Corp DPDT 5amp 120vAC/28vDC

I hope they are correct.

Guess I'll mess with it and see what happens.  Any heads up, drawings, descriptions will help.

How do I attach a picture here?

Thanks  Coo

[jimrice4449]

On the bottom of the switches there are 3 sets of 2 contacts each.   Run two wires from the middle pair to the track on your reverse loop.   Run two wires from the power pack to one of the outer sets of contacts, then continue to the other outer pair of contacts while crossing over so that the right hand wire from the power pack is first connetcted to the right contact and then to the left outer contact.   When completed the bottom of the switch should have two wires conncted to the first outer set of contacts then form an X to connect to the other outer set of contacts and, finally there should be 2 wires running from the middle set of contacts to the track.   When you throw the toggle switch an internal contact will conect the middle set of contacts to either the first outer set or the second outer set and the X shaped connection between the outer sets of contacts is what reverses the polarity.   If it's any satisfaction this little process has, at one time or another, dumbfounded and perplexed probably 90% of MRRs.