Isolating Tracks

St Joe · October 23, 2012, 01:10:28 PM

I am using Bachmann Nickel Silver HO EZ-Track. I have an outer loop using 22 inch radius track and an inner loop using 18 inch radius. I want to connect the two loops using the #6 Crossover switch unit. However, I want to isolate the two loops (electrically) and run one train on each loop with two power supplies. I want to be able to switch either train to either loop. What do I need to do?

rbryce1 · October 23, 2012, 04:07:55 PM

If this is DCC, you probably don't need to go through all that, unless you just wish to. I have 3 concentric tracks, two of them connected with the left and right #6 crossovers, all powered from the same DCC power supply / throttle and I have run 5 engines so far with the EZ DCC controller rated at 1 amp!

If you are saying you wish to use more than one power supply and throttle on each of the two interconnecting tracks separated by isolators, I would strongly say don't do it. First, it is a carnal rule of DCC to never power a track from more than one DCC command controller, but that is not what you seem to want to do. You want to power two tracks from two controllers with them being isolated from each other, but the ability to cross from one to hte other. I'm not sure (and interested to find out) what happens when your engine straddles both systems (forward truck on one system and the rear truck on the other system) and gets conflicting DCC signals.

It may run just fine. It may get a forward direction signal from one truck and a reverse direction signal from the other truck and not know what to do. I don't think it will short, and it may not just shut down. Since there is only one motor to drive two trucks, they will not spin the wheels in opposite directions, thats for sure!

If each system has say 18 volts and the two systems provide voltages at the same time, would it be like DC in parallel where the voltage stays the same and the current available doubles, or like your kitchen oven when it receives 120 volts from one leg of your power panel and 120 volts from the other leg of your power panel to result in 240 volts being applied to your motor windings.

If everything goes fine after the crossover, what happens if your throttle is no longer communicating with that engine? Will it continue to run under the last command or shut down? If the second throttle is not programmed for the engine, it cannot control it.

Guess we need more information about your desired setup so we can all come up with conflicting opinions which will most likely only result in this being resolved by trial & error

!

St Joe · October 24, 2012, 10:30:49 AM

Thanks for all the feedback. I am not using DCC control, just the standard Bachmann power packs. Our local hobby shop advised not to use the #6 Crossover for this application, but rather two #5 Turnouts of the same hand (either right #44566 or left #44565). The metal track connectors have to be removed and replaced with isolators. Any thoughts...I appreciate the feedback.
St Joe

rbryce1 · October 24, 2012, 11:46:08 AM

This is the way I can see it, and others please correct me if I am wrong.

Again, I don't recommend doing it, but if you do, watch your polarity. If one power pack is set for forward direction and the other is set for reverse direction, the engine may see both at the same time during the cross over at the isolators. During the cross-over, if the front truck on the engine recieves a "+ to -" signal and the rear truck on the engine receives a "- to +" signal, you may have a direct short via the wiring.

Normal setup on tracks

Left Side Trucks

Rear Truck Front Truck
|---------------------------|
+ o o o o +
_________________ ________________

Right Side Trucks

Rear Truck Front Truck
|---------------------------|
- o o o o -
_________________ ________________

At the isolated Cross-over point if the transformers were reversed

Left Side Trucks

Rear Truck Front Truck
|---------------------------|
+ o o o o -
_________________ ________________

Right Side Trucks

Rear Truck Front Truck
|---------------------------|
- o o o o +
_________________ ________________

Probably not much of a problem if the engine just blows over the joint, but going real slow or stopping may start to burn wires. Just don't waist time or stop there, and even better yet, make sure the transformers are in alignment with each other before doing the cross-over and the problem goes away.

Again, this is how I can see it, if others know better, please respond.

BarneyJack · October 24, 2012, 02:59:38 PM

Hello St Joe,
In order to do what you are requesting (without converting to DCC), I think you are going to need more switches, and break your two loops into a number of isolated blocks. This is referred to as Cab Control. For additional reading on this, try this link:
http://www.building-your-model-railroad.com/model-railroad-wiring.html

QuoteI want to be able to switch either train to either loop. What do I need to do?

If you only add one pair of switches, you will be limited to changing loops, at least in reference to the to/from perspective, in one direction only. (In other words, with two RH switches, a train moving forward CW on the outer loop can move to the inner loop, but would then need to back through the switches to get back to the outer loop. Likewise, a train moving forward CCW could move from the inner loop to the outer loop; but won't be able to return to the inner loop in the forward direction). Ideally, for ease of operation, I would recommend 8 switches (two opposing pairs on each side of your concentric loops). This would allow you to switch your various blocks between your DC contollers in a fashion that will prevent the shorting of the two power supplies (cabs), and would allow you to control (with some coordination) two different trains either moving in the same or opposite directions back and forth between your two loops.

John

Len · October 24, 2012, 03:32:06 PM

Bachmann needs to either:

A. Get clear instructions on modifying the #6 Crossovers for use in DC layouts right here on the Bachmman web page.

or

B. Redesign the blasted things for use in DC layouts, with jumpers included to bypass the gaps for DCC use.

Len

Hunt · October 24, 2012, 03:32:19 PM

St Joe,
Yes, you need to use insulated rail joiners as the local hobby shop advises or gap the rails at necessary places. Both serve the same purpose.

Suggest both you and rbryce1 obtain book(s) about model railroad wiring or use the many good websites and videos on the web about model railroad layout wiring. Although you are planning on using DC control now, consider wiring with DCC control in mind as it will make it easier to switch to DCC control in future.

Bachmann HO turnouts are all routes-live (not power-routing) and layout must be wired with that turnout type in mind.

rbryce1 · October 24, 2012, 06:08:27 PM

Really Hunt. Could you be a little more specific about these books and where I am wrong. I have many books and have read a lot on line, but none seem to cover the prospect of putting two transformer power supplies on the same engine with reverse polarity. I am definately willing to learn if I am incorrect, but I'm sure all of us would like to benefit from your knowledge rather from your off color innuendos. Could you include the differences he needs to consider between DC and DCC so he can wire it to accomplish both as you suggest, as right now, he has DC.

rbryce1 · October 24, 2012, 09:28:05 PM

Well, you may not feel it was off color, but I do. If that is not how you meant it, I accept that. But the next time you write something like "Suggest both you and rbryce1 obtain book(s) about model railroad wiring or use the many good websites and videos on the web about model railroad layout wiring", you consider whether the person you are writing it about thinks it is off color. I may not have as much experience in model railroad design, but I have a great deal of experience in electrical theory, circuit design and electronics. Again, if you have some suggestions, I'm all ears. If you can tell me where I'm wrong, I'm all ears. But to tell me to go and get educated when you now say you don't have suggestions as to where I am wrong and didn't even read my whole post, I'm sort of confused as to just how to take your comment.

St Joe,

I agree wqith BarnyJack. His sugestion looks like it will provide the protection you will need, in my opinion, to prevent from shorting the power supplies, assuming you are using two seperate power supplies like I think you indicated.

JerryB · October 25, 2012, 12:38:45 AM

rbryce1:

You are so far off base here as to be on a different planet.

The reason you don't see any information on directly connecting multiple power supplies to adjoining sections of common trackage is because it can't be done safely nor operationally. You also don't see any instructions for putting a full sized V-16 diesel engine in an H0 scale model, building a nuclear reactor in the basement to power trains, nor any of hundreds or perhaps thousands of less than brilliant schemes.

Hunt's suggestion was simply that you find some texts on what is both possible and common practice in using multiple DC power supplies to run multiple trains on a layout. That is typically called block control or block wiring, and there are dozens of both free and for-pay resources for this information.

Acquiring a little knowledge in both common and advanced practice in DC (and DCC) model train layout wiring and control, would (hopefully) cause you to not make suggestions that will most likely result in disaster. Recommending (as you did above) that it might be okay to run a train between power sections that are wired to separate power supplies is just plain wrong. Using your instructions can damage engines, power supplies and tracks.

You claim to be an astute electrical and electronics designer. Why not act like one and learn about the application of those skills to model RRing prior to making public recommendations that at best will not work, and at worst will lead to the damage or destruction of someone's equipment.

As to your ". . . off color . . ." statement, I would again suggest that you do some studying: This time use a dictionary and / or thesaurus to look up words, phrases, and their meanings.

Happy (Well Informed) RRing,

Jerry

rbryce1 · October 25, 2012, 07:50:28 AM

Jerry,

In one respect you are telling me I am so far off I am on a different planet, which if I am, I can respect that. But you then say you not only don't say why, but actually agree with me and that I am correct.

I have always been saying, as you stated it, "you cannot directly connecting multiple power supplies to adjoining sections of common trackage is because it can't be done safely nor operationally". This is what I have been saying, while trying to leave the door open if someone does know how to do it.

I never recommended doing it and have tried to show why not to do it unless there are special track wiring conditions to allow it, which I also said I did not know of any.

I did not say Hunt was right or wrong, just that I did not appreciate his tone, and I don't. I appreciate constructive comment. What I don't appreciate is someone telling me I need to go out and get an education and then say he has nothing to offer.

I never stated it was safe to do what he was going to do, in fact, I tried to explain why NOT to do it, for the exact reasons you have just stated. Don't connect power supplies in parallel to run multiple trains on the same layout. You can harm things by doing so.

I said I agreed with BarnyJack and his article seems credible as a way to do it. If you do not agree, could you explain why, not just say we are all screwed up.

As far as the term I used, I did use the right term, as that was the way I took his comment. I do not need a dictionary to tell me what "off color " remarks are. I could have used the word condescending ("behaving toward other people in a way that shows you consider yourself socially or intellectually superior to them"), but that was not what I was trying to say.

I have met and discussed many things on this forum with many members. Most all have been very knowlegible, polite and courteous. A few have not.

I have 3 hobbies which I actively pursue, show cars, boating and now model railroading. I did have a layout when I was a teenager, but only recently got back into the hobby as a bad weather day interest.

I am a member of 12 forums. Two are boating forums, four are model railroad forums and the rest automobile forums. I have not seen on a single other forum where people make comments about each other like the one we are now discussing. It is totally rude and uncalled for.

One member of the Model Railroad forum actually warned me of this regarding the Bachmann forum. I didn't use the language he used, as it would not be appropriate either. At the time I supported the Bachmann forum because I had not seen examples of it. Now I have.

I have had conversations on this forum, on line via private messages and even phone calls from many members of this forum, which were all very pleasant. It's too bad there are some who are not like this. Some agreed with me, some sort of agreed and we discussed various points of view, and some disagreed and we politely and intelligently discussed why. No insults, off color remarks or condescending comments, and yes, I am and did use the correct words.

PS. I am a retired Nuclear Engineer, and I can send you a book on building a nuclear reactor in your basement, including the rod drive mechanisms, shielding and instrumentation. But, since a nuclear power plant is only 18-30% efficient depending upon it's size and insulation, that is not something I would recommend doing either

jward · October 25, 2012, 08:22:55 AM

Quote from: rbryce1 on October 24, 2012, 06:08:27 PM
Really Hunt. Could you be a little more specific about these books and where I am wrong. I have many books and have read a lot on line, but none seem to cover the prospect of putting two transformer power supplies on the same engine with reverse polarity. I am definately willing to learn if I am incorrect, but I'm sure all of us would like to benefit from your knowledge rather from your off color innuendos. Could you include the differences he needs to consider between DC and DCC so he can wire it to accomplish both as you suggest, as right now, he has DC.

For books, i'd recommend "the complete atlas wiring book" as well as the use of atlas's modular wiring components. their wiring system is designed to be easy for beginning mosellers to use, yet flexible enough to grow with you as you expand. bachmann themselves offer no equivalent wiring components.

as for differences in wiring between dc and dcc, as long as the wiring can handle the current, there is no reason a dc wired layout, with block selector switches, can't be used to run dcc. i"ve done it on two different layouts without problems. the block selector switches are set up to switch segments of track to either of two controllers, or disconnect them completely. once you convert to dcc, you simply remove your dc controllers, wire the dcc command station in plaqce of one of the controllers, and set all the switches to that position. if you have a short, you can quickly find where it is by turning off your track one section at a time until the short goes away. or if you want to lessen current draw on your dcc system, you can park them on a spur then isolate that track.

to answer the original poster's question, since gapping and insulating the bachmann crossover is such a hassle, it'd be much easier to buy two #6 and make your own crossover. if you use one rail as a common return, similar to a ground in electrical equipment, you only have to use insulating joiners on one rail. just be sure that it's the same rail wherever you insulate. all of this is covered in detail in the book i mentioned.

rbryce1 · October 25, 2012, 09:46:55 AM

Jeff,

Thanks for the reference. I have 6 Model Railroad books now, but not this one. It is available on Amazon for about 18 bucks, so I ordered it.

Looking through all of my other books, I can not find a description of what actually will occur for the condition we seem to be discussing which seems to have shifted from the posters original question to that of powering a layout with two seperate power transformers at the same time. Most say you should never do it, some are describing ways around it, and my concern is using a way around it may have unforseen bad results.

If an engine is stationary and it's two powered trucks straddle the track isolation gap, and each side of the gap is powered by two different transformers which are, at that time, connected with opposing polarity, like one in forward and one in reverse, what would be the effects on the wiring inside the loco?.

I do not think the track wiring would be in danger as it is probably 16 gauge wire or better, but I believe it would create a short which would conduct a smoke test on the small 22 gauge wiring connecting the trucks together to the motor, but other than theory, can find no reference's to this situation.

What are your thoughts?

jward · October 25, 2012, 12:00:33 PM

i have run into this condition many times. not only is it something that happens on dc block controlled layouts from time to time, but it can also occur in reversing sections if the polarity is incorrect. what usually happens in these cases is that the locomotive, especially if it is equipped with flywheels, will continue to drift into the section of opposing polarity until the motor slows down and pushes it back into the original section. this may happen 2 or 3 times before it stops. remember, dc controllers are much less sensitive to shorts than dcc ones, so usually there is no harm done. if you are going fast enough, you may derail the train the locomotive is pulling.

on a common rail system, the effect of the power supplies seems to be additive. that is, if you are running the train at half throttle, and the opposing controller is set at full throttle, the locomtive will reverse quicker than if they were both set the same.

as kids we used to call these "dancing engines" and drove my grandfather nuts by doing this on purpose.

rbryce1 · October 25, 2012, 01:05:10 PM

Thank you, that is an explaination that makes sense. Even though the condition does ocur, I am happy to see that the damage to the engine I was concerned about does not actually take place.

There is a guy at one of our local flea markets who sells old HO and Lionel equipment. I'm tempted to go over and get an old DC loco and another DC transformer and try this just for grins.

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Isolating Tracks