# Resistance of track sections and connections



## servoguy (Jul 10, 2010)

I have been interested in making tight (read low resistance) connections between track sections for some time. I have tried using an ohmmeter with less than accurate or quick results. A few days ago, I rigged up a Kelvin connection for measuring resistance. It will measure as low as 20 micro-ohms. With this I have made the following measurements:

A good connection between track sections is 1.5 milli-ohms. This is with clean pins and clean openings in the two sections. Also, it is necessary to bend the ends of the section where the pins are installed to increase the contact pressure between the pins and the openings in the adjacent section. With the pins of a section pointing away from me, I bend the left rail where the pin is installed to the left and bend the center rail to the right. I also use pliers to form the ends of the open rail back to where they should be if they are bent out of shape. 

Resistance of a Lionel O-31 curved section = 0.0035 ohms
Resistance of a good joint between sections = 0.0015 ohms
Resistance of a Lionel O-31 straight section = 0.0032 ohms
Resistance of a Lionel prewar 072 curved section = 0.0048 ohms
Resistance of a Lionel prewar 072 straight section = 0.0058
Resistance of a prewar American Flyer O-40 curved section = 0.0040
Resistance of a prewar American Flyer O-40 straight section = 0.0040
Resistance of a Lionel O-42 curved section = 0.0039 ohms
Resistance of a Lionel prewar 072 (711) switch = 0.0100

About half of the resistance of the 711 switch is the wire that connects from the rivet holding the fat rail to either of the other two center rails. This wire is apparently steel and not copper. Replacing this steel wire with a copper wire would reduce the resistance of the switch by about 0.003 ohms. With the steel wire, the resistance is 0.0047 ohms.

The four 711 switches that I tested had a significant amount of resistance between the rivet that holds the fat rail and the rivet itself. I soldered the rivet to the fat rail. 

Making a Kelvin connection requires a constant current supply and a voltmeter than can read down to 10 micro volts. I am using a current of 100 milliamps and reading the voltage with a meter with a resolution of 10 micro volts. I multiply the voltage reading by 10 to get the resistance.


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## Lynn D Bennett (Jul 27, 2013)

My first thought is you are making too much of these connection IF you use the guidelines MTH publishes for DCS operation. That is a lock-on every 12 sections of track, positioned in the middle of the block. They want the block to have individual wire runs from the transformer to each block in 16 gauge wire (star wiring). I ran four MTH DCS engines on my whole layout and did not exceed 5 amps. The losses in the track rail connections would be minuscule compared to the available 18 VAC.

I think the same would be true for even a variable voltage conventional layout.

So, use the rule of 12 sections per lock-on, star feeders of 16 gauge wire, and you should be fine. The voltage losses at the locomotive at the end of the block will be less than 1% even with the worst track you tested.

Even I don't follow that rule and I have no connectivity problems. I run four distributed lock-ons on a hundred section of track with no blocking and 16 gauge star wiring. My DCS signal strength measure nearly 10 (out of ten) almost everywhere on my layout.

If you are having problems with connectivity then solder the track together but I highly doubt that is necessary with the track sections you tested in your post.

Lots of lock-ons is the key.

LDBennett


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## sjm9911 (Dec 20, 2012)

Lynn, I belive servoguy is trying to do it with the least amount of lockons, to show how his way of connecting tubular track works. And it does. Were not talking dcs here but it might be promising. I have no where near the amount of lockons your suggesting, when , and if I hook up my legacy I'll post if there is signal problems. But I dont have much power loss if any. On your larger runs dosent the command system compensate for power loss?


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## Lynn D Bennett (Jul 27, 2013)

sjm9911 said:

*"On your larger runs dosent the command system compensate for power loss?"*

It is impervious to losses in track voltage within limits but it would only effect the top speed if anything. The engine has a flywheel with marks on it. It counts the marks as the motor turns and compares it to the command it gets from the controller and puts a voltage to the motor. If the command and the counts don't match it adjusts the voltage up or down until they do. It is like the speed control in your car that you set for a speed and the car adjusts the throttle until and forever to maintain that speed. It is a "closed loop" in control systems nomenclature. The voltage on the track limits the top speed the loco can go. When it is 18VAC continuously that correspond to nearly 100MPH on most engines. My layout has nowhere on it that it can do much above 50MPH without flying off the tracks on a curve. So I have lots of headroom before my locomotives are impacted by loss of voltage to the track.

It is a poor choice to minimize lock-ons and wiring. It is asking for places in the layout where the voltage is low for conventional control. MTH pushes their approach to assure good communication with DCS. They even have a mode on the controller that tells you the quality of the signal to the engine in real time as the engine moves around the layout.

Another fear with bad connectivity is the heat developed in the high resistance track section interconnection. Under the some conditions it might start a mini-fire (??).

There are excellent ways to power a layout and other ways that kind of work most of the time. For me the last thing I want to do when I run trains is to have to be chasing track voltage problems. Do it right the first time and you probably will never have to do it again or have to fix it.

Anyway that's my opinion and yours may vary.

LDBennett


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## servoguy (Jul 10, 2010)

Lynn,
I am running conventional, and so voltage drops in the track are a problem. The locos I run don't have any closed loop speed control. BTW, I got out of engineering school 51 years ago, and have been doing electrical engineering and analysis of dynamic systems ever since.

I want to minimize the voltage drop around the track so I can use a minimum of lockons. Since my layout is on the floor, I want to minimize the amount of wire.

The last layout I made had 53 sections of track in the outer loop, and the voltage drop from the transformer to the far end of this loop was 0.25 volts with my 2353 pulling about 8 postwar cars. This track was O-31 straights, 072 curves, 042 curves, and 040 curves. All of the track sections had the pins offset to minimize the joint resistance. I have been using this approach to minimize the resistance of the joints for about the last 7 years. It works well. 

I definitely don't want to solder the track sections together as this is a floor layout and that would be difficult and probably damage the carpet. 

One additional thing: I have a lot of old track that is somewhat rusty. Tonight I am cleaning out the ends of the sections to get rid of the rust. Buying new track is not an option due to the amount of track I have. It would cost a fortune to replace all my track.


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## sjm9911 (Dec 20, 2012)

Servoguy, did you ever try the rust inhibitor , electrical conductor gel. I did use your method of putting together track. But I added the gel. It woeked for me. Or it could be that your method worked. Curious as to weather or not it makes a difference. I do not have the equipment to measure or the smarts to do it .


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## servoguy (Jul 10, 2010)

The track I am working on is track that was somewhat rusty when I got it. Some is recently from eBay. Other is track I have had a long time, like about 40 years. It was rusty when I got it. I don't have any trouble with things corroding here in Florida as long as I keep it in air conditioned space. Can't store trains in the garage or attic. Too hot and humid.

I have some prewar locos with zinc wheels and they all have the original wheels. One came from Texas, two from Oklahoma, one from Missouri, and I don't remember where the others came from. 

I may get some corrosion inhibitor to see if it will remove rust from pins and ends of rails.


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## Lynn D Bennett (Jul 27, 2013)

servoguy:

I too graduated as an electrical engineer 51 years ago! Funny that!

Even in your situation I think using lock-ons every 12 sections (that is only four in your 53 track section layout you described) is the best solution. Old tubular track often has trouble maintaining tightness with the flexing that occurs when laid over carpet. With four lock-ons you minimize the possibility of dead spots. If you can find heavy duty high amperage 120VAC ZIP line wire (moulded plastic insulation that encompasses both wires) then the star wiring would be minimal at four wire pairs from the transformer but watch the polarity of the connections.

While poor conductivity between section does reduce the available voltage, that effects little except the max speed of a convention engine as it limits the max voltage to the motor and unstable speeds as the connections make and break. Connectivity that is lost is the thing that should be avoided. Many lock-ons minimizes that. Tubular track by its nature is shaky at best for maintaining good electrical and physical connectivity. While your testing and fixes may initially reduce dead spots with minimal lock-ons, with use and time the situation may change abruptly. More lock-ons is better than individual initial low resistivity section to section connectivity, in my opinion. And the cost for implementation is minimal.

Some of the rust conversion liquids convert the rust to some compound (black looking?) that may or may not be a good electrical conductor. A little testing probably should be done before a large effort on all your track.


LDBennett


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## servoguy (Jul 10, 2010)

Lynn,
After 63 years of playing with Lionel trains, I feel my approach is the best. If you bend the rails where the pins are installed, the connection will be tight and the track sections won't come apart. Running conventional, it is important to keep the connections tight. Lionel's recommendation of pinching the open end of the rails to make a tight connection doesn't work very well. That is what I did until I discovered a better way. The other advantage of bend the rails where the pins are installed is that you only have to do it once. You can take the sections apart and put them together again without bending the rails again. 

The reason that you need so many lockons is that Lionel's method of making the connections tight doesn't work well as there is little or no contact pressure.


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## Lynn D Bennett (Jul 27, 2013)

The recommendation was for MTH Track system by MTH. Seams they too have connectivity problems if you don't use lock-ons every ten to twelve sections. But I used four for about 100 section of track with no problems of connectivity. Now alignment of rails from section to section is a different story as well as getting some engines through their switches.

I appreciate you have lots of experience but it seems so simple to just add lock-ons and the star wiring rather than having to tweak every piece of track you own. But hey, its your choice to make and NOT mine.

LDBennett


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## cshabino (Jan 8, 2013)

Would you please refresh my memory on how you bend the rails where the pins are inserted


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## servoguy (Jul 10, 2010)

Look in the first post.


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## servoguy (Jul 10, 2010)

Lynn, One of my primary objectives it to minimize the wiring since this is a floor layout. Also, the 072 track and switches I have and the American Flyer O40 track and switches are about 80 years old. It is time to refurb the track and switches to make sure that the layout doesn't have any connection problems. I think I have found the solution to making tight connections between sections, and I will post more about this in the near future.


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## servoguy (Jul 10, 2010)

Lynn,
There is a problem using lockons on rusty track. The lockons don't make a good connection with the rusty rails. I have found that Marx lockons make better connections than Lionel lockons.


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## servoguy (Jul 10, 2010)

I am still working on restoring rusty track, and when I get a method that I am satisfied with, I will post it.


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## TrainLarry (Jan 15, 2012)

By far the most effective method to clean up rusty track is the electrolysis method. Very simple and inexpensive, it is the method that museums and other restoration facilities use to restore their items. Electrolysis is the method that produces rust, and we use electrolysis to remove it. Remove the connection pins, and you will get both the outside and the inside rust free with very little physical effort involved. No harsh chemicals, no wire wheels or hand cleaning is needed. No harm is done to non-metal parts, including the insulating fish paper. I have done track, tools, and pieces of very rusted steel with this method and can attest to it working well. My latest project was a solidly rusted motor for a car moon roof. I immersed the entire motor in the solution, and an hour later I removed it and was able to disassemble it, clean and lubricate it, reassemble it and return it to service good as new. The time needed to clean up track would probably be an hour or so in the solution. Rinse off the track, let it dry and it is useable as is.

Larry


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## rkenney (Aug 10, 2013)

The electrolysis method sounds good, and I am just lazy/curious enough to try it.

I used a similar method from a book as a child with salt water and mimeograph stencils to etch my name in some wrenches.

But if you have used this on track, you didn't share your technique. A couple of obvious questions that come to mind are:
Does it destroy the paper insulators for the third rail? 
Since the method requires a complete circuit through both the part and the electrolyte, does the third rail need to be electrically connected to the two outside rails?:stroke:


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## TrainLarry (Jan 15, 2012)

Bob,

The insulators do not get affected by the process or the solution. Once dry, the track can be placed in service. 
A short length of wire can be tied around one outside rail and the center rail. A stack of track can be put into a large, non metal container and the negative electrode placed on one track. The current will pass through all the track, and do them all at once. 
Use copper wire to connect the charger positive wire to the anode material. Steel will dissolve away.
See here for a large vise treated with this process.

Larry


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## servoguy (Jul 10, 2010)

Thanks, Larry. I think I am going to try your method. Sounds good!


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## gunrunnerjohn (Nov 10, 2010)

Have you actually tried electrolysis on tubular track Larry?

I've tried EvapoRust on track and a lot of other items, it does a great job of removing rust.


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## TrainLarry (Jan 15, 2012)

You're welcome. Be sure to show pictures of before and after. You know we love pictures here!

Yes I have, John, and it works well. The process will not harm non-rusted metal. 

Larry


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## gunrunnerjohn (Nov 10, 2010)

Larry, we need pictures. 

How about detailing the setup you use to do the cleaning. Do you first have to clean the track before doing the actual electrolysis?


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## sjm9911 (Dec 20, 2012)

http://www.modeltrainforum.com/showthread.php?t=17961&highlight=electrolysis
Some pictures of the process I remembered seeing on this forum!


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## TrainLarry (Jan 15, 2012)

John,
There is no preparation of the track that is needed beside cleaning off any loose dirt and rust, and you really do not have to do that, as you are immersing the track in detergent.
Get a bucket and add enough water to cover your work. Add 1/4 cup or so of the washing soda (Arm and Hammer brand Washing Soda - found in the detergent aisle of your local supermarket). Mix the solution. If you are doing track, stack them in a pile in the bucket and connect the negative clip of a car battery charger to the top track. For the anode, get a piece of scrap steel or stainless steel and either solder, or wrap the end of a copper wire through a small hole drilled in the steel. The key is you do not want the positive battery clip under water with the current flowing, as the clip will slowly dissolve away. (From personal experience). The negative battery clip will not be affected under water. Place the anode near, but not touching, the track, and turn on the power. You will immediately see a stream of small bubbles between the anode and the track. The rust will slowly come off, and form a dirty film on top of the solution, as seen in the linked photos. The closer the anode is to the track, the faster the reaction. You can shut off power after about an hour and check progress. Reapply power if more action is needed. There is no maximum time limit, as the process is self-limiting. When the rust is all dissolved off, the current flow will fall off to a negligible amount. You can safely leave items in overnight if necessary. The water temperature will slowly rise with a heavy current draw; this is normal and does not inhibit the process.
When you are done, let the rust sink to the bottom and the solution can be poured down the drain, as it is detergent, or it can be reused indefinitely. 

Larry


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## gunrunnerjohn (Nov 10, 2010)

Sounds interesting, that's for sure. Now, if you could only re-plate them after the process, they'd be like new!


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## TrainLarry (Jan 15, 2012)

If I'm not mistaken, electroplating uses a very similar process as this. With the proper electrolyte and anode, you could plate your track with gold if you want.

Larry


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## servoguy (Jul 10, 2010)

It is a little difficult to Electroplate holes. The electric field in the holes is small. This makes it difficult to plate the inside of the rails.


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## geophyte1 (Dec 9, 2014)

*Looking For Feedback On the Electrolysis Track Cleaning Method*

By this time I'm assumming at least a few people will have tried the electrolysis track cleaning method outlined in this tread.

Three questions:

1. How has the method worked for you?

2. Any caveats we need to know about?

3. In cleaning track with electrolysis, does it remove the black paint on the track flanges?
Thanks,


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## sjm9911 (Dec 20, 2012)

To be honest I would use a scotch brite pad to clean the rails. If there really rusted, the track is cheap enough to buy more of. If its something else, evaporrust works wonders. It just seams that using electrolysis to clean track is complicated so I never tried it I'm sure it will work well if your inclined to try it out. For vapor rust just dunk it in, no need for batteries , steal pieces or wires


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