how to access motor on Bachman Spectrum 4-4-0 American (circa 2000)

JimmyB said:
But surely grease in NOT conductive, so will reduce or even eliminate the contact usability.
Click to expand...
Here we go, grease is not conductive, but the electricity will get through... a light grease will still allow conductivity.

Lps and Deoxit are not conductive either. But while it goes contrary to "logic", enough metal to metal occurs that grease coated contacts will pick up.

Also LGB conductive grease is NOT conductive. And you don't want to use real conductive grease, it tends to get everywhere and you get shorts.

By the way DeOxit is great stuff, to keep oxide buildup down, it leaves a thin anti-oxidation coating down.

If you don't know this stuff, happy to educate, but we should start a new thread, since "common wisdom" will be opposite to what I am saying. (but electrical engineers and physicists can explain).

The key is that the contact patch is very small, and even with grease on it, some metal will be in contact.

Greg
 
Greg Elmassian said:
Here we go, grease is not conductive, but the electricity will get through... a light grease will still allow conductivity.

Lps and Deoxit are not conductive either. But while it goes contrary to "logic", enough metal to metal occurs that grease coated contacts will pick up.

Also LGB conductive grease is NOT conductive. And you don't want to use real conductive grease, it tends to get everywhere and you get shorts.

By the way DeOxit is great stuff, to keep oxide buildup down, it leaves a thin anti-oxidation coating down.

If you don't know this stuff, happy to educate, but we should start a new thread, since "common wisdom" will be opposite to what I am saying. (but electrical engineers and physicists can explain).

The key is that the contact patch is very small, and even with grease on it, some metal will be in contact.

Greg
Click to expand...
Nice, always like learning something new. Would you reccomend the DeOx or LPS for the wipers/axel in this case? I was leaning towards the DeOx, but the LPS3 is "technically" listed as a grease.
 
So, in this case, I would go with the DeOxit, a self-limited thin film that won't attract dust and dirt.

Being close to the roadway, I would think LPS would pick up most stuff, and like WD-40, is not intended as a permanent lubricant, at least from my testing. LPS has been around for years, and more of a temporary lube and break free in my opinion.

You should not really need grease on that nice contact patch.

Greg
 
Greg Elmassian said:
Here we go, grease is not conductive, but the electricity will get through... a light grease will still allow conductivity.
Click to expand...
Greg you can't have it both ways, if electricity is going through anything including grease, it is conducting it, regardless of how thing the film is. There may be some resistance but it is still conducting the electricity.

Conduction
noun [ U ]
US
physics, chemistry
The flow of electricity or heat through a substance
 
Jimmy, I somehow knew you would come back on this.

The electricity is not going through the grease, it is where metal is touching metal. Let me help you a bit... start by telling me about a car wheel bearing, which is packed with grease.

Do you think there is a film of grease where the ball/roller touches the bearing race?

Just yes or no... If yes, you need to talk to a mechanical engineer or physicist (you are already talking to one of these, hint)

Bottom line, there is enough actual metal to metal contact even with grease, that electricity conducts, and the actual area of conduction is very small.

Greg
 
Greg Elmassian said:
Jimmy, I somehow knew you would come back on this.

The electricity is not going through the grease, it is where metal is touching metal. Let me help you a bit... start by telling me about a car wheel bearing, which is packed with grease.

Do you think there is a film of grease where the ball/roller touches the bearing race?

Just yes or no... If yes, you need to talk to a mechanical engineer or physicist (you are already talking to one of these, hint)

Bottom line, there is enough actual metal to metal contact even with grease, that electricity conducts, and the actual area of conduction is very small.

Greg
Click to expand...

Greg Elmassian said:
Here we go, grease is not conductive, but the electricity will get through... a light grease will still allow conductivity.
Click to expand...
I am a Registered Mechanical Engineer, but this statement is then incorrect, the light grease does not allow conductivity, but allows metal to metal contact, your statement not mine.
 
Jimmy, you need to talk to someone who knows, other than me, or spend the years in college to understand (as I did).

Basically in this case, oil or a light grease will not stop the brushes from picking up power. There are enough small areas of metal to metal contact that the grease will not affect conductivity.
(clearly dirt or grit or something so thick that it lifts the wiper will stop conductivity)

Again, you are a mechanical engineer, not an electrical engineer, nor a physicist, and do not realize that the actual paths of where the electrons actually move is very small. It's an interesting subject, and I have told you a bit about how small the areas are that actually do the conductivity, but you seem to ignore or just not believe.

So the surface is still lubricated, but electricity can flow.

Perhaps this will help you if you consider it with an open mind:

You know that people put LGB grease in rail joiners... but power still flows... how can that be? It's lubricated. The grease is not conductive at all.

Why does this work: because there is enough metal actually touching at any one time that current can flow.

If you still want to argue, call up a university and talk to someone with a PHD.... (in electrical engineering or physics)

Greg
 
Greg Elmassian said:
Jimmy, you need to talk to someone who knows, other than me, or spend the years in college to understand (as I did).

Basically in this case, oil or a light grease will not stop the brushes from picking up power. There are enough small areas of metal to metal contact that the grease will not affect conductivity.
(clearly dirt or grit or something so thick that it lifts the wiper will stop conductivity)

Again, you are a mechanical engineer, not an electrical engineer, nor a physicist, and do not realize that the actual paths of where the electrons actually move is very small. It's an interesting subject, and I have told you a bit about how small the areas are that actually do the conductivity, but you seem to ignore or just not believe.

So the surface is still lubricated, but electricity can flow.

Perhaps this will help you if you consider it with an open mind:

You know that people put LGB grease in rail joiners... but power still flows... how can that be? It's lubricated. The grease is not conductive at all.

Why does this work: because there is enough metal actually touching at any one time that current can flow.

If you still want to argue, call up a university and talk to someone with a PHD.... (in electrical engineering or physics)

Greg
Click to expand...
Greg, the grease discussion has been going on a long while, and as you know both copper slip/cote/whatever (lots of commercial names), LGB graphite grease etc., are not actually greases. Part of my studies included hydrocarbons (including lubricants), so I have a good understanding of grease in in it correct form. I think some of this misunderstanding is the terminology used. I think we should leave it here, and agree to have our own views :)
 
OK, not trying to define grease, and I believe I said oil too, but a thin coating of any grease, or oil in moderation will still allow conductivity, the point is that there are still enough small patches that are metal on metal to allow conductivity.

And to go with that, it is important to realize that the actual contact patch size required is VERY small.

Those are the 2 salient points.

I don't get into the makeup of the greases, whether natural hydrocarbons, synthetic, etc, because not relevant in this case, the discussion is about electrical conductivity with a light coating of oil/grease/hamburger fat/whatever. The topic of friction/wear vs lubricant type is another whole kettle of fish as you know, and I do acknowledge some things are not greases,

(But LGB "conductive" grease is a lithium based grease with powdered graphite added in and it is in no way conductive itself).

Greg
 
Greg Elmassian said:
OK, not trying to define grease, and I believe I said oil too, but a thin coating of any grease, or oil in moderation will still allow conductivity, the point is that there are still enough small patches that are metal on metal to allow conductivity.

And to go with that, it is important to realize that the actual contact patch size required is VERY small.

Those are the 2 salient points.

I don't get into the makeup of the greases, whether natural hydrocarbons, synthetic, etc, because not relevant in this case, the discussion is about electrical conductivity with a light coating of oil/grease/hamburger fat/whatever. The topic of friction/wear vs lubricant type is another whole kettle of fish as you know, and I do acknowledge some things are not greases,

(But LGB "conductive" grease is a lithium based grease with powdered graphite added in and it is in no way conductive itself).

Greg
Click to expand...
Greg, I did say lets agree to differ and drop this discussion. Or I will just leave it at that :(
 
Summary:
It's complicated..
But, in general terms, some light lubrication (grease or oil) will not do any harm.

PhilP
 
You must log in or register to reply here.
Back
Top