Hello,I'm thinking about adding a crossover to my existing layout, but am concerned about "reverse loop" implications. I run all of my trains using DCC only (Bachman Dynamis DCC). Shown in the picture below is a very basic illustration of my mainline with the crossover in question. What components, if any, do I need to make this work so that polarity isn't an issue. I would like to make this as simple as possible with no operator type moves on my end (throwing switches). Is this possible? Will I be able to run trains in either direction to each other if I want and not have worry about anything, other than them crashing into each other?
Thanks for any help you can provide,Steve
I would imagine a DCC auto reversing module would be all you need. It's been the topic of a few posts lately and exactly how it works I can't say but it does the polarity switching for you. I am only assuming that it some how sense the direction of the locomotive and switches the polarity of the track wiring accordingly.
Here is a link to Tony's trains one of the dcc guru's of the hobby I am sure a better explanation of how it functions can be found there.
yes I'm curious too, I would guess a reverser but I'm thinking only 1 direction of travel ,but I hope I'm wrong.... some body here knows...J.W.
Insulate both rails at the joints marked with an X And then install something like this on one of the now isolated loops.
http://www.hobbylinc.com/htm/bac/bac44912.htm
Dave
Lackawanna Route of the Phoebe Snow
Phoebe Vet install something like this on one of the now isolated loops.
install something like this on one of the now isolated loops.
Phoebe Vet,Do I need an auto-reverse module for each side? totalling two modules. Also, I assume I can use other brands besides Bachmann, correct?
Thanks for the help. This seems like a simple solution, assuming it answers my question regarding trains running in either direction as well.
Steve
You only need one and yes, you can use other brands. I showed you that one because you have Bachmann now. If you follow these posts you are probably aware that I am not a fan of Bachmann.
I prefer, and use, Digitrax, but there are several really good brands available and the choice is a personal preference.
DCC is symmetrical, the engine does not care about polarity. The auto reverse module is there to prevent short circuits when the track loops back on itself and while the powered units are crossing the boundary between segments where the polarity is reversed.
It works automatically and seamlessly.
Phoebe Vet You only need one and yes, you can use other brands. I showed you that one because you have Bachmann now. If you follow these posts you are probably aware that I am not a fan of Bachmann. I prefer, and use, Digitrax, but there are several really good brands available and the choice is a personal preference. DCC is symmetrical, the engine does not care about polarity. The auto reverse module is there to prevent short circuits when the track loops back on itself and while the powered units are crossing the boundary between segments where the polarity is reversed. It works automatically and seamlessly.
Thanks again Phoebe Vet,I understand where you are coming from about Bachmann. The Dynamis works "ok" for my needs right now and was the cheapest of the bunch. BUT...I can see moving on to Digitrax, MRC, or one of the others down the road.
I have just one more question about this reverse loop thing though...well actually two. (1) It almost seems to me that you need two modules because each end is a reverse loop? (2) are there any special concerns with switch machines controlling the crossover turnouts that I should be aware of?
All that is important is that the two sections are completely isolated from each other. The auto reverse module, when it senses the short as the engine passes across the gap, will reverse the section that it controlls to match the polarity with the one it doesn't control. It does not matter whether the train is entering or leaving the controlled section. If the two sections already match, it will not do anything.
I highly recommend Digitrax. I have the Super Chief.
Look more carefully, Dave. I did not just isolate the crossover. I divided the track into halves at the crossover.
Other Dave.
Perhaps this diagram is clearer. The blue side controlled by the auto reverser. At no time would the train be crossing two transitions at once, and I doubt that he would be running a train longer than the blue section since it appears to be about a third of his mainline. It WILL work, and you only need ONE reverser.
Dave B:
Maybe it's my fault. Perhaps I did not make my diagram clear enough. I don't think you understand where I suggested the OP put his 3 breaks in the track. There is no very short section. It is not possible for the train to cross two of the breaks without going around one end of the mainline or the other.
If he had drawn a double crossover, it would be different, but he did not. Check his original diagram.
Dave P
One thing has me a little puzzled, would the reversing loop only be required if the train were to change direction correct? If the train were to travel from the outside loop to the inside loop still continuing in the same direction a reversing loop would or would not be needed?
Allegheny2-6-6-6 If the train were to travel from the outside loop to the inside loop still continuing in the same direction a reversing loop would or would not be needed?
If the train were to travel from the outside loop to the inside loop still continuing in the same direction a reversing loop would or would not be needed?
There's only one loop (oval actually) with a crossover between the two sides. A train will change direction every time it uses the crossover.
If you install the crossover then you will need the auto reverser. The switch will cause a short if it's not insulated between the switches, and if it is insulated, the train passing over the switch will cause a short. The auto reverse module, with the three electrical breaks I described, will make the proper polarity changes to the loop to which it is wired when it detects that short.
As Dave B said, the loop must be longer than the train and the loop that is controlled by the reverse module must be isolated electrically from the rest of the layout. It will be if you put the breaks where I showed you.
Hey all,Great discussion going on here! I really appreciate all of the help and input. I have my crossover just about done. Just waiting for the glue to dry to move on to install the auto reverser. I have one more concern....Will I need to add power feeders to each turnout in the crossover, between the frog and the insulated railjoiner between the two turnouts? my thinking is that this area becomes a dead zone which may stop a locomotive as it goes through the crossover.
Thanks,Steve
No, you will not need feeders there.
Make sure that you use insulated joiners on BOTH rails at all three places I marked with an X.
Ignore those circles, they are just marking regular joints by the program I used to make the diagram.
Well, I got everything hooked up for my crossover and BAM!....recieved a short-circuit as I ran my loco through the crossover.
I'll refer you to the illustration of portion of my layout below. As you can see, I hooked up my MRC auto-reverser from what I thought was the correct way (notice the blocks placed within the crossover). The directional arrows show the direction the trains go to perform the "loop". The yellow dashed lines indicate that I also tried installing the yellow wires from the auto-reverse unit there....again with no luck. I'm lost and a little frustrated.
Just a little more info for you. The crossover consists of (2) #6 Walthers/Shinohara "DCC ready" turnouts. The rest of the track is Atlas flex 83 and custom-line turnouts. All other tracks shown end in "stub end" yards.
Any help is GREATLY appreciated!!!-Steve
I agree with CSX Robert. The section that you have set up to be the reversing section must be powered ONLY by the reverser, otherwise when the reverser changes the polarity of the power going through it it will cause a short through the reverser.
gtw1969-Steve
-Steve
Hi I reread your original post and have a question. How do you get the loco to cross over without a turn out. "switch"?
Lee
Ok, I've rerouted my wiring (Shown in illustration below). I completely isolated the main bus wires from one half of the layout from the other. The bus wires are joined together by the MRC auto-reverser as shown. One one side of the layout I have my DCC controller. Just for reference, I've also shown a few feeders.
So with this setup, it still doesn't work properly. The loco stalls/short circuit's as it goes over the crossover (isolation joiners). If I push it along so that both sets of trucks are on the same side of the isolation/loop, it will start up again.
Any other ideas based on what i've done to remedy the problem? Thanks!!!
yankee flyer gtw1969 -Steve Hi I reread your original post and have a question. How do you get the loco to cross over without a turn out. "switch"? Lee
gtw1969 -Steve
CSX and Phoebe are correct. Check your wiring and be sure that the isolated section of track forming the loop is only wired to the auto reverser.
Yankee Flyer raises a good point too. If all of the other tracks shown in your diagram lead to stub ends, how does your loco ever enter the crossover? From the direction of movement indicated on your diagram, the loco could bypass, but not enter, the crossover. Very confusing.
Rich
Alton Junction
gtw1969 Ok, I've rerouted my wiring (Shown in illustration below). I completely isolated the main bus wires from one half of the layout from the other. The bus wires are joined together by the MRC auto-reverser as shown. One one side of the layout I have my DCC controller. Just for reference, I've also shown a few feeders. So with this setup, it still doesn't work properly. The loco stalls/short circuit's as it goes over the crossover (isolation joiners). If I push it along so that both sets of trucks are on the same side of the isolation/loop, it will start up again. Any other ideas based on what i've done to remedy the problem? Thanks!!! PS - Yankee flyer, if you notice I have a crossover in the middle of a dog-bone style layout. Look at my orginal picture. Thanks.
PS - Yankee flyer, if you notice I have a crossover in the middle of a dog-bone style layout. Look at my orginal picture. Thanks.
gtw1969,
You don't want to isolate two sections of bus wire from one another. The bus wire should remain unbroken. You need to isolate any feeders from the isolated section of track (the loop) and run those feeders to one side of the reverser, while the unisolated section of track (the remainder) is powered to the other side of the reverser by a feeder from the bus wire.
Here's the full illustration of my layout with updated arrows. The way I want the crossover to work is having a train come out of the Hamtramck yard, then go into the crossover, so that when it loops around it can run up into Zug Island, and visa versa. I hope this clears it up.
Can you post a COMPLETE diagram of your layout showing ALL the track and the locations of all the feeders?
Your original post showed only the mail line loop.
I suspect that you have a feeder someplace that is connected to the isolated loop. It might be in a siding, or there might be another connection to the non reversing loop that is not apparent on the partial diagrams you have posted so far.
Almost all of your sidings are electrically on the left side of the insulators, even the ones at the extreme lower right of the physical layout. I assume that there are numerous feeders among them. If you wire your reverser to reverse the loop on the right side of the insulators, that looks like it's a simple loop with only one very short siding.
Phoebe Vet Almost all of your sidings are electrically on the left side of the insulators, even the ones at the extreme lower right of the physical layout. I assume that there are numerous feeders among them. If you wire your reverser to reverse the loop on the right side of the insulators, that looks like it's a simple loop with only one very short siding.
Exactly Phoebe Vet.I've completely shut off the right side of the layout really. I have my auto-reverser going from the main bus wires on the left side to a set of track feeders only on the right side. With that, it still doesn't work. I've tried to cross the wires on the one side of the auto-reverser with the track feeders, and then the loco will go through the crossover but when it comes around and tries to go over the gap (closest to the small siding), it shorts. I thought this was going to be simple. Hmmmm
As far as where are all the feeders? I can assure you that they are all going into the bus wires on the left side of the layout. No feeders or bus wires are connected to them from the right side (loop area). They are there, but not connected to anything that has current running through.
If you get a short as it crosses the insulators that clears when it has completely passed, then it is either not reversing or the changing of the polarity is causing a short.
1 Be absolutely certain that the reverser is wired correctly.
2 Recheck that there is not a feeder from the main buss still going to the right side, Perhaps it is on the siding.
If you want to check the reverser, connect a couple of pieces of flex track with insulated joiners, hook the power and reverser up with alligator clips, place them on the bench or the floor, and run back and forth over the joint.
If I was closer to MI I would come have a look, but alas it is too far.
CSX Robert,I think that might be the case as well. After going over every square inch of my wiring, I can't seem to find any faults. And you mentioning my Dynamis shorting out quickly.....that is happening. I have read about those other auto-reverse devices (solid state), and decided to go with the MRC because of cost (middle of the road really). I wish I had an MRC based command console to see if it works with it, but I don't. Looks like I might have to splurge and get the solid state version or maybe just keep it simple and hook up some kind of SPDT switch if that is possible.