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Author Topic: Suitable loop track  (Read 769 times)

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Offline swanmark

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Suitable loop track
« on: March 07, 2011, 10:19:06 PM »
Hi Guys its me again, I need some advise about a piece of track i want to build a loop, hope i can explain this right, it will have 2 circles either end so a loco will go around one circle then on to a length of straight track over to the other circle, then back along the same straight, is there any turnouts or pieces of track that will allow me to do this without having to change any points and of course without causing a short, thanks

Offline zwilnik

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Re: Suitable loop track
« Reply #1 on: March 07, 2011, 10:40:51 PM »
So to clarify, you're planning a single straight with a reversing loop at each end?

If so, that's one of the classic bits of tricky track laying and wiring for DC (not so sure about DCC, but betting it's still tricky with the polarity reversal).

Generally you have to isolate at least one side of the reversing loop so you can reverse the polarity of the controller current as the engine passes into it. Do-able but a bit fiddly.

If you do it so that there's a long enough section of track on one side of the loop for any of your engines to fit in, isolate it from the rest of the track with plastic joiners, and set up a switch so that you can switch it on and off, you'd run the train around with it set to 'off' until the engine stops in the isolated section, reverse the controller and throw the points then switch the section back on again and the engine will continue on to the straight in the reverse direction it was travelling.

One trick you can theoretically do with the points is if you isolate them so that the points aren't supplying current to the loop, you can tweak the spring in the points so that it only softly holds them to one side and doesn't resist the force of wheels pushing through them the wrong way. That way the train will always go into the loop in one direction (as going 'with' the points, the rails are held by the spring), but after the current is switched and the train returns down the other side of the loop it can simply push through the points without them having to be switched. It's theoretical though (and somehow doubt it has a real life prototype in anything other than roller coasters) and would require a bit of careful wiring to get the isolation right.

If you want to be really sneaky, one way around it is to build some interleaved track. I've seen it on an Irish layout before where a bridge wasn't wide enough for 2 track running but needed trains in both directions on different tracks, so they laid the rails interleaved. So it was track 1, left rail, small gap, track 2 right rail, gap, track 1 right rail, small gap, track 2 left rail. Looks like you've got 2 rails on each side of the sleepers, but that lets you run trains in each direction without them technically being on the same track. It would all be very custom and involve laying the rails individually (let alone the custom crossovers to get them interleaved), so probably not a solution for you, just potentially cool :)

 

Offline cupoftea

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Re: Suitable loop track
« Reply #2 on: March 08, 2011, 10:04:27 AM »
If you have a bit of electrical know-how you could fit a sensors that will operate the point motors when a train passes over them and could also be used to automatically switch polarity on the 'straight' track.

Offline cupoftea

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Re: Suitable loop track
« Reply #3 on: March 08, 2011, 07:29:43 PM »
Hi Mark

Heathcote may be able to help you: http://www.heathcote-electronics.co.uk/

 

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