Hi, This has been touched on in different threads but really not asked or answered that I can tell. This has to do with placing a non-powered section of rail inside a reversing section to prevent metal wheels from driving the auto reversing unit nuts. In theory the reversing section should be longer then the longest train but as we all know there are times when that is not possible. I have some cars with metal wheels and one caboose that draws power from the rails with some electronics inside it. I really don’t want to find out the hard way and let the smoke out of the caboose because of a short. So far I have not run any of the metal wheels through either of my reversing sections while the loco or locos are passing through the other end. Here are the questions: Do both rails need this at both ends of reversing section? In N-Scale would a space of about ¼ inch be adequate or should it be the length of the largest truck that would be crossing the section? Would cars with lights or in my case my caboose require a longer section then cars without lights? Gary
This is a timely question for me. I just installed a PSX-AR's and it reverses polarity several times when I run a train through it. I was thinking it may be the caused by the metal wheels.
I am no expert, but I have had DCC for a number of years and had reversing tracks. I don't see how metal wheels in and of them selves would be a problem UNLESS you are spanning both sides of the reversing section. If an engine goes into the reversing section and the main and reverse area are not in phase, then the reverser sees a short and flips the reversing sections polarity to match the approach track. No subsequent wheels coming into the reverse section should cause a short even if they are drawing power... now if the engine crosses out of the reversing section and the reverser trips again, and there are still wheels crosing the aprooach gap, they will short. This is why the section needs to be longer then the longest train. None of this answers Gary's question. (smile) I think that you would need a section that was as wide as the span of both of your trucks to prevent the caboose pickups from getting power. If it were only as wide as one truck then there could be a time where one truck is in the reverser and the other side is outside... so it seems like you would need a section as long as our outside wheel base to be safe. That is a BIG span! Maybe it is better to attack it from inside the caboose with diodes? I am not an electronics wiz :-(
Sean has it about right. If you have single metal wheels in the train, away from the leading locos, a short gap of 1/4" or so will solve the problem of the train being longer than the reversing section. But if you have any electrically coupled wheels, such as with illuminated cars/caboose or helpers, they will bridge the gap and the problem can come back. You cannot make the gap big enough to avoid this as your locos will then stall on it. Diodes would be very difficult to arrange, if even possible. For starters you'd have to electrically separate the pick-up from each wheel.
1 - Yes. Always both rails. You might get away with doing it at just one end of the section, but it's taking a chance. 2 - It only needs to be longer than the 'tread' of a single wheel. 1/4" is fine (I'd maybe go to 1/2" for #1 scale). 3 - See my post above. Almost insoluble unless you only pick-up from the wheels of one truck in which case making the break longer than that wheelbase should work.
1) You must gap both rails at BOTH ends of the reversing section. You can't do just one end as the section would not then be isolated. 2) OK if multiple axles of the truck/bogie are not connected. For an all-wheel pickup loco, you would need it to be longer than the loco, which would then shut down, defeating the whole purpose of the hobby! 3) No matter how you slice it, you can't cross gaps at the entrance and exit of a single reversing section from the same train/consist, as the reversing section would be doing the cha-cha, with the booster or power manager throwing up its hands, declaring an "unresolvable" short and shutting down.
I'mmmmmmmm Back Hi again, I may not have stated my situation properly in my first post, so I’ll try again. My stub-ended yard sits at 90 degrees to the main and is connected to the main with a wye so that trains can enter and leave the yard while traveling either direction on the main. One leg of the wye (Blue in attachment) is the reversing section. Both ends of the reversing section have both rails insulated with plastic rail joiners. The reversing section will hold a train of X amount of 50 ft cars and one of my longest locos. In theory my train will not be longer then the length of the reversing section. Most of my cars have plastic wheels, a hand full have metal wheels. One car (caboose) with metal wheels draws power from the track. One truck (both axles) of the caboose gets power from the north rail and the other truck (both axles) from the south rail. My concern is when (and it will happen) I make a train that is made of X amount of 50 ft cars and one of my longest locos plus the caboose. With that length of that train, the loco and the caboose will be crossing the gaps at both ends at the same time. My questions arise from reading other threads that mentioned similar problems and have suggested that a short section of non-powered rail be put next to the insulated gaps within the reversing section, which would in actuality extend the gap. My main questions are: How long should this added section of non-powered rail be? I know it needs to be short enough that the loco can cross it with out stalling. Does the added section of non-powered rail need to be at both ends of the reversing section? Thank you for you patience, Gary
Gary, I think there is a way to avoid this issue altogether. Instead of making one of your wye legs the reversing section, make the yard itself the reversing section. Simply put the gaps between wye turnout that leads to the yard (offset them slightly, as previously suggested) and the two legs that lead to the yard. Then no matter how long your trains are, they will never cross those two gaps at the same time, and you also get the side benefit of making the yard a separate power district without the cost of additional hardware. If the arrangement that I suggested isn't clear (to either you, or anyone else reading it), let me know, and I'll draw it up. ---jps
1. Since your caboose only draws power from one truck for each rail, the non-powered rail only has to be slightly longer than one truck. 2. If the train will pass through in both directions, then yes, the non-powered rail has to be at both ends. I think the best answer is what Shooter said, make the yard the reversing section.
Hi, Thanks. I understand what you are suggesting (Blue is the reversing section in the attachment). That will work for the yard but there are other reversing sections on my layout that will have the same potential problem that are not a wye. Gary
Yep, that's it. Can you draw up and explain those situations too? Maybe we can come up with something. ---jps
You could make everything except the strait track across the top be the reversing section as well... _____ Y Like that. Just cut the Y off at the diverging route on each switch on the main.
Hi, Thanks everyone for all the suggestions, but I'm about to forget the whole mess, and change all the wheels to plastic and return the electronics in the caboose back to operate off of a battery as it was when I first added it to the caboose during the 1980's. The track plan can be found here. Please be advised that it is not to scale. The other reversing section is located almost dead center left to right and is in all that spaghetti above the (3) in "Team Tracks (3)." This reversing section will hold about 1/2 the amount of 50 ft cars and a loco as the section coming off the yard I believe that may have answered my questions. I can easily cut some additional gaps using my roto-tool and and some styrene and ACC glue if I decide to continue with this. Rewiring the yard is not an option I wish to tackle at this time.
Double gap it at the locations in red and you will have no problem. Wire that section (yard and tracks) not to the buss, but to an auto-reverser and then to the buss and you should be good to go.
There has to be a way to do this WITHOUT rewiring the layout. The wye for the yard is not the only concern. I know that others have the same problem because the suggestion for the non-powered rails came from other threads on Trainboard.
Okay, then you can basically do the same "trick" with that section. Basically, you put one gap in that reversing section (or crossover) above the "3" that you pointed out. Then you put a second gap on the mainline, approximately under the "I" in "Industry 1". Then you put a third gap on the mainline, approximately above the "u" in "Industry 9". Industry 1 & 2, and the loop of mainline around Industry 4 (and more) would then become the "reversing section", and this would not require addtional hardware. This plan should allow for very long trains too. The second and third gaps could be located in other places to minimize the need for the autoreversing section to "flip" during planned operations, or for a longer train. For example, the second gap could be moved around so that it is to the left of Industry 6. Or the third gap could be moved to the mainline right in front of the turnout for Industry 2 if you have a really really really long train reversing around that loop. Anyway, I think you get the idea. Again, anyone who may be confused by what I'm talking about, I can draw on a copy of Gary's track plan. Now, depending on which track you plan on using for the "drill track" on your yard, you might want to modify all of the gap locations (or even add a fourth power district so that the electronics manage it better). But I believe that should work. In the meantime, in the caboose, if you use a simple four diode matrix to power your caboose electronics, I think you can make it so that you can pickup power from both trucks without tripping the autoreverser when the two trucks span a "reversing gap". You should be able to set up a four diode matrix for each truck, then connect the pos and neg outputs of each diode matrix together. Of course, an additional four diode circuit in an N-scale caboose is no trivial matter, but it should work. Again, if that's not clear, I can draw that up too. ---jps
Sorry Shooter. Didn't catch the part about the wiring. I guess with out understanding how you wired your yard, it would be difficult to answer. You have me stumped. I change my vote to plastic wheels and no lighting int he caboose.
Well, we're talking about a few different things at this point. As far as the auto-reverser wiring, please refer to the track plan below. There are two sections where Gary's layout requires a reversing section. One is in the wye by the yard, and the gaps for the yard reversing section are shown in blue. The other is the small crossover at the top of the plan, where the gaps Gary planned for that section are shown in green. But the green reversing section is shorter than some train lengths, which causes a problem. The gaps for one possible alternative to the green reversing section are shown in red. These are general locations, merely to show how one can avoid short reversing sections in such arrangements. In Gary's case, we're trying to avoid having a reversing section shorter than a train due to electronics he has in a/some cabeese, and metal wheels he has in some cars. If avoiding a reversing section shorter than a train length is not possible or desirable, and you will have a lighted car(s), or even metal wheels on the layout, a simple gap at those locations may cause problems (with the metal wheels shorting across the gap). So the general suggestion is to "double" the gap, in other words, have two gaps at each location less than an inch apart, with the rail in between those two gaps "dead". If you're only concern is metal wheels, the length between the gaps only need to be 1/4" or so. If you're concern is also trucks that pick up power for lighting or some such thing, then the distance between gaps needs to be longer than the longest "powered" truck. Additionally, one would also have to draw power from only one truck (unless the electronics were modified), otherwise a short would occur between the front and rear trucks. If the car has a DCC decoder onboard, you may be limited to drawing power from only one truck. But if the car has simple electronics that are merely pulling power from the track (for a flashing rear light, for example), you should be able to pull power from both trucks. In the attached diagram, the top circuit shows a standard diode bridge (which aligns the power polarity) that would be used to power such a flasher circuit. But this setup would electrically connect the front and rear trucks, and would cause a car so equipped to trip an auto-reverser. But if you use the circuit at the bottom (with separate diode bridges), the car can draw power from both trucks without tripping the auto-reverser. While that was a little long winded, I hope it's clearer now. ---jps
Hi Shooter, If I can get over the phobia of doing a major rewiring (number 3), which is needed, your placement of the gaps (blue and red) will solve my problems. Currently the reversing section at the top has the gaps where your have the green gaps, I had never thought of making the top section as large as you have it. But I could not get past using only 2 gaps.:tb-mad: As to the caboose there is no problem there, besides the rectifier bridge I had to put in a voltage regulator to drop the DC voltage down to 3 volts. Thanks for both of the drawings. Gary
Gary, do you really need that crossover where the green marks are? It looks very non-prototypical to my eye; possibly a modeller's kludge to make life easier than real life Given the grief it's causing you, ripping it out might be a better solution.
