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Subject: 
Re: Reversing Loop without Insulated Tracks
Newsgroups: 
lugnet.trains
Date: 
Wed, 11 Aug 2004 05:37:42 GMT
Viewed: 
1674 times
  
In lugnet.trains, Larry Pieniazek wrote:

SNIP

  
I prefer the more conventional approach. Polarity switch controlled reversing loop segment to handle short avoidance.

But that’s just me. I STILL think it’s a very clever idea, and working through why it works (despite momentary shorts) is a great way to understand how LEGO turnouts do power routing.

Hi Folks,

For what it’s worth, this is the layout w/ reversing loop I was playing with. As always, I’m limited in size to something that fits on the big kitchen table I use for train layouts. I wanted a way I could be going “roundy roundy” and then decide to change the direction of the train without the “Big Hand in the Sky” coming down and reversing all of the cars and locomotive.



The controller connects on the right part of the layout.

I started out thinking the train would be going clockwise and then when I wanted to switch I’d have the train enter the crossover from Points A. It required a mildly complex sequence of stopping and starting the train and flipping switches to avoid shorts until I could get the train out from Points D going counter-clockwise.

By accident I discovered that if I went clockwise but entered the crossover from Points D, I could make the transition with less steps, less switch flipping, and without requiring Points C to be there at all. Of course this required the train blasting through Points A and pushing through until the motor stopped, just as Ville Tuominen devised in the scheme that started this thread.

For those who are interested, here’s the sequence for entering from Points D:

1) Start off with the train going clockwise and the points setup like this: Points A,C,D : Straight; Points B : Curved

2) As the train approaches Points D, switch it to curved and wait for the train to cross over and grind to a halt just beyond Points A. As ROSCO has pointed out, if the train is going too slow it can get stuck on Points A and cause a long lasting short, so make sure you’re moving quick. (Note, Points B must be curved prior to this or you’ll have short city from the moment you switch D!!!)

3) Reverse direction on the controller.

4) Switch Points D back to straight and watch your train start moving counter-clockwise.

5) Switch Points B to straight before the train drives onto the siding and off into your trackside structures. Make sure you switch Points B back to curved before you reverse the process to turn the train around again!


If you want to avoid momentary shorts you can always enter the crossover from Points A but the process is a bit more complicated:

legend: S = straight, C = curved

1) Clockwise roundy roundy : ABCD = SCCS

2) Enter crossover at A : ABCD = CCCS

3) Stop controller right before train reachs C.

4) Setup to exit crossover at D : ABCD = SCSC

5) Start controller in opposite direction

6) Stop controller once train has exited

7) Setup for Counter-clockwise roundy roundy : ABCD = SSSS or SSCS

8) Start controller again


Last but not least: Re-read Larry’s post and realize that all of this can be done a heck of a lot easier with just a few pieces of paper :-)


Regards, Paul



Message is in Reply To:
  Re: Reversing Loop without Insulated Tracks
 
(...) I suggest you read up on reversing loops for some background. There are plenty of references out there if you use Google to look. But, failing that, and also for the benefit of the rest of the readership... Consider an ordinary reversing loop (...) (20 years ago, 11-Aug-04, to lugnet.trains, FTX)

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