Crandell - You may recognize this as it was your idea.
About a month ago I had a thread on my track plan and you rec I
insert a curved section of track to allow me to turn entire trains.
Well I tried and tried until I finally got a radius that was
satisfactory (26.5in). So thanks for some great advice. I
ended up with a 6 ft section at 2.5% but I think that will be OK.
My
question now for Crandell or whoever wants to chime in is How to wire
it up? I have one rev unit but I think I may need two?? I
need to isolate points B and C from point A. But what about point
D? Will that need to be isolated and/or another rev unit used for
it??
Sorry for not having a hot link. But for some reason with my
Netscape browser once I publish a thread any changes I make don’t show
up. Here is a link to the image above.
I have a few questions for you about the trackage.
Is point G an overpass, or do the tracks cross at grade?
If one track is above the other at point G you only need to isolate the trackage between the turnouts at points F and C, and wire a single reversing unit to that trackage.
Since that is the case, you should only need to isolate the C-F trackage from the rest of the main and wire it to the reversing unit. I don’t think it would be any different that making a reversing loop with a single turnout.
I have a reverse loop similar to yours and the local DCC wizard recommended one PSXAR for the wiring. While I haven’t laid that portion of the track yet, after asking even more questions I am comfortable with the eventual outcome.
Hey, Terry!! Sorry, but I am late signing-in today…other things going on.
First, I am happy that you have managed to introduce this valuable asset to your operations…I hope that it will be something on which you look back and give yourself a thumbs-up. The first time you turn an entire train to run it the other direction, and you don’t have to do anything but line a couple of turnouts, you will be mightily pleased…I’m pretty sure. I have full confidence in my PSX-AR, now in service for 10 months.
I always have to work hard, my brain wired the way it is, to figure out where best to control shorts on a reversing loop. However, I agree with the others. The added section, understandably, will also mean an adjustment in power since it turns the train from the way it was running (and getting power from two rails side-by-side), so logically that is where to control polarity.
Your PSX-AR has input terminals and output terminals, sets for each at either end of it. Input power also has to have DCC signal for the loco passing through, so your controller will feed the PSX-AR on the left side. On the outputs on the right, two wires go anywhere you want them to, provided they are within the confines of the gapped reversing section of track. If it were me, I would use the natural gaps at the ends of both turnouts so that you have full advantage of the entire length of the contiguous turning section at your disposal for maximum train length.
Cut your flextrack carefully (measure twice!) and leave about 1/16" at each gap, no more if you can help it. As a tip, place one end at one turnout, nailed using the small holes in one tie, and a couple more nails nearby, and then form the section using your pre-drawn centreline. Lay the loose end directly over the turnout rails, and use a sharp metal object, or a fine marker, to mark precisely your cutting points. Check once more that the rails on the o
Thank you for everyones help. I really think I have a handle on this now.
Crandell - Tks again for your insight. So what you are saying is my train can only be as long as the gapped rails between pt C and pt F? Thats almost 16 ft so I should be good. I anticipate car lenghs of 12-14. I notice in the directions for the PSX that there are three sets of contacts that can go to the rev section. J2 pins 1-2,3-4,5-6. Should I connect one set at each end of the rev sec? As far as head clearance I have with the 2.5% grade a clearance of 3.3 inches. I guess I should make a mockup here in the next couple of weeks to verify that will be enough. Better to find out now than later after the glue dries. Tks again.
Remember that your grade should start gradually, so it will take a little more space, or gain a little less height than you’ve calculated. And make sure you’ve got the length to get back down. If this is HO (I don’t remember) 3.3" is going to be tight by the time you add the structure. A mock up may be a good plan!
Terry, as Jeff cautions above, you should have easements, or transitions, into and out of the grade at each end. They don’t have to be long, maybe 8-10" between the onset of the transition and the actual constant grade. That means you actually have less grade distance to get the clearance you feel you have…which means you’re actual grade will have to be that much steeper, maybe closer to 2.7% between the transitions. Not a biggee.
As for where to place the feeders, I wired my loop in two places: one is on the bridge span that runs diagonally across my operating pit because it is hinged to swing down. So, it is necessarily separated from the rest of the layout electrically. Accordingly, I had to run one set of feeders to that 4’ of rails, and they come from the PSX-AR. I won’t go into the details, but the same sub-bus feeding the span also feeds the rest of the reversing loop. In that case, one other set of feeders rises to get power to that section.
I would think that you could use two pairs of feeders along your reversing section. If placed at the location of thirds, IOW at just over 5’ apart such that they split the section into three nearly equal lengths, you will find the signal and power robust.
Crandell - well I am confused slightly (ok complety). The only rev unit I have ever dealt with was for my TT. when you say feeders for my rev sec you don’t mean feeders like on the rest of the layout. Wires dropping down to the RAIL A, RAIL B of the Booster. You mean feeders coming from the PSX-AR output side? There are three sets. So If I understand you correctly I can actually have up to three sets of feeders coming from the PSX to the rails on the rec section. I hope that makes some kind of sense. Well now that I said it out loud it does make sense.
Just look at the documentation. There are three outputs together, but there isn’t any need to run feeders back to each one. For your reversing section just run a bus (just like for the rest of the layout, but not connected to it) with feeders, and powe rthe bus from one output of the PSX. I think the idea of the other outputs was to power additional loops. The idea originally (and it is still true, though as prices come down it is less of an idea) was that you could use one auto reverser for multiple reversing sections. As long as you didn’t have trains triggering both sections at the same time you could get away with it, since the polarity doesn’t matter, only shorts.
Jeff - tks again. I’m really picking your brain tonight. Makes sense. But just to be sure if I wanted to I could use all three outputs on one loop (not that i am). I did read the documentation and I miss understood apparently. But now I got it. Tks
It should not matter if Point G is a crossing or an over pass. If it is a crossing, the two sets of tracks could be insulated from each other to not cause any electrical problems.
If you’re concerned that your grade will be excessive, might I suggest two alternatives ?
Rather than having the C-F section go up, have the other track (E-D and beyond) go down. It would seem that it has to pass under a bridge at the far left of the diagram anyway, so why not have it pass under the C-F section as well ?
The C-F section go up AND the other track (E-D and beyond) go down. This would reduce the amount of elevation change each track would have to make in order to have adequate clearance. Each track would then achieve the necessary elevation change (which, when combined, give you the necessary clearance), in a shorter length which can also reduce your grade.
Personally, I think that 2.5% is asking a bit much from your locomotives, and could affect operations. Also, in HO, you’ll find 4" is better for clearance.
This is where a mock-up would help. If you are modeling a particular road, then make up a typical train and see what it does on the grades you envision and with the curvatures and clearances you plan. If you have a culvert or small trestle in mind, put it in place and test for clearances. A test bench takes the guesswork out of track planning.
I found that I could cut the supporting sides of my WS stone portals down by about 3/8" such that the resultant clearance of just 2.8" from rail top to the apex of the portal arch left about 1/2" above my tallest steamer. It may be too short for proto scale, but it looks decent. More importantly, it works.
