It’s been awhile since I have posted. I’m in the process of connecting the top and lower decks. Been doing reading of past posts here and I think I have this right but would like a second, third… opinion. [:)]
The top and lower deck will be connected by a double track helix in the connecting track I was going to put 2 crossovers which will allow me to reach the staging tracks as well as send 2 down or 2 up the helix at one time and send them in either direction on the deck.
I’ve attached a simplified schema/design of the layout. The Red marks are where I think the isolator gaps should be and the green highlighted area is what I think the reverse section should be. Does this look correct to you?
Thanks for your help,
Dave
PS. This is not to scale in any way shape or form. If you need the actual layout I do have it but I think it may confuse the question.
My only concern is the length of the reverse section. I know this is not a scale diagram, more of a schematic, so hopefully this isn’t really a problem. As drawn, though, the distance from the insulators on the crossover to the insulators on the big loops is very short. Ideally, it should be longer than the longest train you plan to run on that section of track, so that you don’t have a situation where the lead engine crosses one insulator while a metal wheelset is bridging the other insulator.
Thanks for the reply. This is all in N scale and my longest staging track (ie longest train) is 50 inches including locos. The amount of track between the cross-over and loop turnout is 60. Cutting it close but I think it will work.
I have a Digitrax system and I am thinking only 1 of the autoreversing modules would be needed, sound right?
Yes, one auto-reverser is all that would be needed. I’ve got an older Tony’s Trains one, and it has provided years of rock-solid service. The Tony’s reversers are all solid state, no relays, so they throw faster and are more reliable than any of the relay-based units on the market.
The longest train length with which you need to be concerned is the segment of track the train will be on. In your diagram, that could be the distance from the switch by the staging to the switch by the closest loop, not the distance from loop to loop.
Just for my edification, let me see if this is right:
If the train (assume just one train is on the tracks) is partially on the brown track and partially on the green track, that’s okay. But if the front of the train is on brown, the middle is on green, and the rear is on brown, that’s not okay. Is that correct?
That’s basically it. Basically, you can’t bridge both ends of a reverse section at the same time. It doesn’t have to be the same train; it could be two separate locomotives. You can get away with freight cars with plastic wheels, because they won’t conduct electricity and therefore won’t affect the reverser. A metal wheel will momentarily bridge the gap. Even with that, you may have one of those “works most of the time” situations, because a solid-state auto-reverse is very fast, and it may flip-flop between polarities a number of times while the train passes through the reverser.
I haven’t tried this, but another way to reduce the metal-wheel problem would be to use a short (1/4 inch) section of styrene as a rail gap. This would prevent the metal wheel from ever touching both rails at the same time. Of course, this is a “dead spot,” so you should keep it away from turnouts or crossovers where other dead spots might combine with it to stop an engine.
Like engines where the wheels on one whole side are electrically linked together, reverse sections need to accomodate passenger cars with track-powered lighting, which do the same thing. Even freight cars with metal wheels and trucks will bridge the rail gap for quite some time while crossing over it. You’re not going to fix this issue with a 1/4-inch dead zone.
You shouldn’t run more than one train on the green part either. If so the same problem as with a too long train will occur. The solution is to dived the green part in two sections with their own auto-reversers .
That is probably not a good idea. You shouldn’t connect two auto-reverser controlled sections together. If you do, the circuitry in each of them will detect the need to reverse polarity, and both will flip at the same time, particularly if you use the same model of auto-reverser for both sections. When you get into this situation, the auto-reversers are “fighting” each other. You may have to lift the bridging engine or car off the tracks to clear this.
As an aside to the original question, perhaps you all can answer my basic DCC reverse loop question…
I am “fixin” to go DCC on the next layout, and am currently in the design phase. My existing DC layout has two reverse loops and I use the Atlas controller to route the powere for them. I confess that about a third of the time, I mess up on the control as a train if going thru the loop. For DCC reverse loops, Digitrax has an “auto reverser”. Is it truly automatic operationally or is there manual intervention to make the polarity correct as a train goes thru the reverse section?
DCC autoreversers are totally automatic. They detect the short when the train hits the gaps and reverse the polarity, fast enough that the train doesn’t stop. You do still have to throw the turnout. The polarity flipping happens so fast, even with the relay based Digitrax AR-1 (which you will no doubt see ‘reviews’ saying the relay based devices are too slow, etc) that you won’t see it happen, just hear it click. I never see anythign happen with the trrain on my friend’s n scale layout, and those locos don’t cost very much - they’re mostly too small to have flywheels or anything to help them out (scratch built small steamers, not nice big modern diesels). I suppose if you motored over the gap at 1 tie per minute speed there might be a slight hesitation.
The nice thing about DCC is the ‘polarity’ (more correctly the phase) has nothign to do with the direction the loco movies. So you CAN still do reverse loops the old-fashioned way with a DPDT toggle. Only in this case, you flip the togfgle controling the loop when the train is fully inside it. Versus the DC method of changing the mainline polarity to match the exit of the loop. That’s right, in DCC you flip the polarity right under the moving train. That’s what the autoreverse units do anyway.
The only phrase that comes to mind is “wow, that is soooo cool!”
I figured I would avoid reverse loop situations on the new layout and manually turn the steamers - but now it looks like I can put in the loop and “forget about it”!
There is one other thing to note about auto-reversers. They do not work for DC engines running as Engine Zero on DCC. As Randy described, flipping the phase/polarity of a DCC signal does not affect the speed or direction of a DCC engine. However, it will change the direction of a DC engine. So, when you enter the loop with a DC engine, the auto-reverser will flip over so that the reverse section matches that end of the main, and the DC engine will continue into the loop normally. At the other end, though, the auto-reverser will once again flip the phase/polarity of the loop track, and the DC engine will do an about face and head back the other way. You could end up watching what appears to be a ping-pong match.
This should not be a big concern. Realistically, running DC engines on your DCC layout is a poor workaround. The night-and-day difference between this and putting in a decoder makes the choice kind of a no-brainer.
That’s very close to what went through my head watching an engine run through my own auto-reverse section for the first time.
Yes, I can see that us subway modellers think alike. If you run a DC subway train, you could use an auto-reverser to flip the polarity at each end of the line, thus reversing the train and sending it back. It would work for a trolley, too.
Thanks to all that have added to this. I think I’m going to go with the single auto-reverser because honestly it will only be used in a few moves namely taking trains from staging to the upper route. Most of the traffic will come from staging to the lower route as that is how the layout runs.
Finishing up the wiring of the first section of the reverse loop that I posted about above… DCC Station is a Zephyr hooked up to my N-scale layout.
For the reverse loop controller I went with a DCCSpecialties PSX-AR (what the hobby shop had in stock). I’ve programmed it to trip at 1.2 amps and turned on the InRush boost but it will not reverse correctly. I have spent some time on the phone with DCCSpecialties making sure everything was wired correct and settings are correct and have also swaped it out with a second one to make sure it wasn’t a bad unit. I’ve also had a local “seasoned” modeler look over the wiring and he agrees everything is fine.
I’ve tried taking the Zephyr off the layout and building a testing area on the bench but still no luck, I was wondering if you have come across anything like this before or had any suggestions?
On another note I’m not sure if this is recommended but I h
What happens when the train crosses the gaps? Does the PSX-AR trip, or does the Zephyr trip? Try turning off the Inrush Boost (I’ve had 4 soudn locos tunning on my Zephyr, shorted the track on purpose, and when I removed the short they all started FINE. Unlees you have a dozen sound locos sitting on the tracks I doubt you will have inrush issues - and certainly not with N scale).
You might also try setting the Zephyr short response time to a longer value by changing OpSw 18 to Closed (see page 47 of the manual). This will give the PSX-AR more time to react since it’s time is NOT configurable.
