Hi Friends, My layout ends......or starts, in a 6 track terminal.....with 3 platforms........2 tracks to each platform. I plan to install a double crossover beyond each platform so that I can direct the train onto the correct outbound track and to shunt incoming trains into the appropriate empty track. Plainly, my problem is how to wire each double crossover. Each will have 4 turnout controls (switches) to control the 4 turnouts and these will be controlled by a DPDT switch. The turnouts will be paired and each pair will be controlled by a DPDT switch. Power... DCC..... will come from beyond the crossovers so that as the turnouts align there is no conflict in the direction of the current. I hope my description is clear. Thanks to all for any help that can be offerred. In a way this is a similar problem to the "Loop" .
Can you just clarify what you are planning here, as the terminology is subject to, er, 'interpretation'. By double crossover do you mean 2 tracks with 4 switches (turnouts) and a diamond in the middle? Or something else? Are you using live or dead (insulated) frogs?
Yes, the terminology can be confusing, particularly the word "Switch." It does not look like Black Cloud's photo. It is two straight tracks with 4 turnouts and the frogs are insulated. I have a photo of it in my computer but I don't know how to get it into this forum.
Peco calls what you're talking about a 'scissors crossover'. I can't find a pic of it that is not in PDF format, except for this one made by the Lego people. I've also seen one in Bachmann EZ-Track.
Yes! You got it! I bought mine from Walthers. In "Normal" position the train will run along the straight track. In order to switch tracks 2 turnouts must be activated.......those that are diametrically (Sp?) opposed. Easy enough.......one control can activate 2 turnouts.......but now you're messing with the polarity. In yesterday's mail I received one of those "How to" wiring books. It says nothing about double crossovers but it does outline the wiring for a single crossover using the DPDT switch. I believe the wiring should be the same. Does anyone disagree?
If the frogs (including the corners of the diamond) are all insulated, then there may not be any wiring to do. The manufacturer will probably have connected the rails 'internally' to the appropriate running rails. You could check this by applying power to one rail and then use a meter or lamp to see which rails have power; repeat for the other rail, then the other track. If it was a live frog version like the Peco one above it'd be a lot more interesting
No Mike, the frogs are all insulated unlike the Peco. The problem is one of polarity. My "right" rail is positive both eastbound and westbound. When the switches are in normal position the polarity on both sides of the crossover corresponds. When the turnouts are activated and the train crosses from one side to the other, it will short circuit. My solution is to keep the tracks in the station unpowered. They will receive their power through the turnouts. I'm not certain that this won't cause other problems in the future but I'll give it a try. Howard
"My "right" rail is positive both eastbound and westbound" sounds as if you have something like this: (Where red = 'positive' and blue = 'negative' of your DCC feeds. (It's actually AC so may be better to think of it as live and neutral.) This is at best tricky, and likely impossible to sort out. If it is the way you have it, I recommend you change it to this: which will be whole lot easier.
Assuming it is a PECO - why not email them? I've always found them most helpful Shortliner(Jack)away up here in the Highlands
Yes........the "right" rail is always positive. If the left rail were positive, the engine would go in reverse. The polarity has to be consistent all over the layout. ( It's DCC) This situation is similar to a loop where the track doubles back on itself. The loop has to be isolated......a gap in the tracks......and then a switch must be thrown to reverse the polarity before the engine re-enters the mainline. I'm hoping that the DPDT switch that activates my turnouts also reverses the polarity.
Sorry I'm a bit late; been away for a while. If it's DCC then the 'polarity' has nothing to do with the direction the engine moves. Yes, loops have to be dealt with specially in both DC and DCC because they are a short-circuit situation, but what you have here is not a loop. Please, please, change your wiring so that the 'polarity' is the same on all tracks. Eg. if it is an end to end make all the rails on, say, the viewing side of each track 'live'; or if it is an oval or similar then make all the rails on the outside 'live'. If you have any reversing loops then isolate them and deal with them separately.
I'll give that a try. It won't be for a few weeks though. I'm still sorting out the exact location for the terminal and a few other things. I'm modelling a fictitious railroad in the era of the 50's which is patterned after the Long Island R.R., a commuter line. Mine will not be a commuter railroad and I'll also have freight. So there are many odds and ends that need to come together. My first priority is good track. I can see that every piece of track must be perfect otherwise there's bound to be trouble..."down the line."
