brass transformer rollers

Do not know your answer but brass is considered a softer metal IMHO.

That is my understanding too, but copper is even softer than brass.

According to what I see on the web, copper is given as 2.5 - 3, and brass is given as 3-4 on the mohs scale (10 is the hardest)

I am under the impression that the hardness of a piece of brass with vary with the alloy composition.

I recall that some years ago, someone was producing rollers made of real gold and claimed that they offered much better conductivity, longer life, and lower heat buildup. I would have them tested before assuming that they are made of brass. Maybe with todays prices for gold you can cash them in!

Eric Hofberg

TCA, LCCA

The rollers in the ZW are Carbon because is is cheaper to

replace a carbon roller than the transformer coil. The carbon

will wear out before the copper transformer coil will

wear. There was a dentist that made a replacement roller

out of gold. Gold is soft and a better conducter than carbon

but now that gold is $1600 per oz the rollers would be too

costly.

I'd remove them post-haste and replace them with the proper carbon rollers.  As others have said, they're going to damage the transformer coils with continued use, that will be the end of that transformer!

I did replace the rollers while I had it apart.

I am going to save the brass ones as a curiosity.

The power cord was rotten and in need of replacement.

The "Z" was a pleasure to work on. It was designed in a manner that allowed for very easy service.

For those not familar with the "V" and "Z" transformers, they even have adjusting screws to allow the laminations to be held tightly.

There is another reason for the use of carbon rollers on these transformers. During operation it is not unusual for the roller to contact two adjacent windings shorting them together. This is not much voltage but the potential is there for significant current flow. The carbon roller resistance acts to lower this current. If a metal roller is used the life of the transformer is lowered and could result is a burned out core.

Al

hello guys and gals.......

How about nickel-silver rollers ?

the woman who loves toy trains

tiffany 

Good point about the carbon rollers and resistance.

Tiffany, nickel-silver would be low resistance, see the prior post by Al.

I saw a video made in the 90's "The magic of Lionel trains" New Buffalo, Mich. : TM Books and Video, 1993.

One of the layouts featured was that of a jeweler. He replaced his zw with gold rollers and was selling them as a "upgrade".  Don't know who he was, but I am curious if those "brass rollers" are a little more valuable than standard brass.

I think I can tell the difference between brass and gold.

Another reason carbon is used is that it has no liquid state.  It changes directly from a solid to a gas.  If there is any arcing, all that is given off is CO2.  There are no metalic deposits left on the transformer coil that would, in time, short the bars.

Interesting point as well, never thought of that.  I should know this, I ran the projectors in a drive-in for a couple of years in high school!