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What is a "conductive lubricant" and why do I care?

5089 Views 12 Replies 8 Participants Last post by  Mike O
There's a thread on another forum that brings up a good FAQ that bears repeating, and actually has information for newbies and experienced modellers alike.

So here goes another "Techno-Greg" thread.

I think at one time or another we have all heard of a "conductive lubricant". Wow, that sounds great!

It seems to make sense that if you have power pickup on an axle, a lubricant that was ALSO conductive would be a great thing. Well it COULD be.

First: let's talk about what is REALLY conductive or not.

In the model train industry, I only know of ONE product that is plastic compatible and says "conductive" on the outside. That's LGB "conductive paste" in the red and white tube.

This stuff is NOT conductive. I don't care what the tube says. Put an ohmmeter in it. Yes I know it has graphite in it. But it's not solid graphite, but little particles in suspension in a nice grease. Not conductive. Period.

There are other "conductive" products, that are NOT plastic compatible. Aristo has one called "Electra Lube". It's actually somewhat conductive, not enough to help anything (more later), but it is documented to destroy certain plastics, notably the first generation of Aristo truck sideframes: //www.aristocraft.com/vbulletinforums/showthread.php?t=5686

There are "conductive lubricants" that are kind of a light oil/clear fluid. They are not conductive either, but it does not matter, they eat plastic, and say not for use on plastic. They are more like "tuner cleaner" in a light oil base.

There are also real conductive lubricants with copper, silver, or gold in them. They are VERY expensive, and do conduct electricity. They are not normally plastic compatible. The danger here is they spread everywhere, so even if it did not attack the plastic sideframes, it has the potential to create short circuits on insulated wheel sets, and many other parts. Just not practical to use. (This stuff is often used in electrical wiring and large high current wipers in moving equipment).

Then why are people calling something conductive when it's not?

This is because the best thing you can do to keep metal surfaces conductive is to keep them from oxidizing. Just as oxidized brass rail does not conduct well, virually any oxidized metal surface does not conduct well.

So, if you put grease in your LGB rail joiners before assembling, water and air cannot get in, and it keeps the joint conductive. Basically any grease will do. In the auto industry, when we had rotors and distributor caps, what grease was put on the contacts? Silicon grease. It's a wonderful dielectric, i.e. insulator, by itself.

But wait! how can this work, I put an insulating grease on my axles? How does the electricity get through?

This is the part you have to understand. It actually takes a VERY SMALL patch of "clean metal" to make electricity flow. On a round axle, the actual contact "patch" is very small, but on that very small part, the pressure is very high. High enough to make sure the metal parts touch.

So all you need to do is keep the metal clean, unoxidized.

What's the bottom line?

Use the appropriate lubricant for your axle bearings, grease or oil, use grease on wipers or rail joiners. You can still use the contact cleaner and lube stuff on your motor commutators, but use it sparingly.

The bottom line is the electricity WILL get through, just keep it clean and oxide-free.

Regards, Greg
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RE: What is a "conductive lubricant" and why do I care?

The best thing on the connectors is probably a silicon grease, it would be clear and not messy if you got it on yourself, if I am understanding your type of connectors.

Regards, Greg
RE: What is a "conductive lubricant" and why do I care?

Should not hurt anything Mark, it's an OK grease. I prefer other greases though, like the hob-e-lube, and aero-locomotive greases... the hob-e-lube has moly in it, better than graphite in my opinion.

Most of these "dark" greases are lithium based.

Regards, Greg
RE: What is a "conductive lubricant" and why do I care?

My experience has been that the silicon dielectric grease is normally friendly to plastic, but it's lubricating qualities are not as good as "purpose designed" lubricating greases. I would not use it on high load lubricating tasks. It's more often used for insulating, keeping out moisture, and lubricating O rings like in filter housings.

Regards, Greg
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