[GreenKeys] Model 14 TD distributor rings

[Bruce Gentry]

Carbon tetrachloride is dangerous to health, ozone depleteing, and 
difficult to get. A good substitute for it would be non-flammable 
formula brake cleaner from an auto parts store. There is truly no need 
to clean off the brown film formed by carbon-copper contacts. Keeping 
oil off of them and carbon dust from building up between the segments- 
where it can create a short- is all that is needed. If the TD has sat in 
a damp place for decades and the copper has green corrosion on it, or 
the entire surface is black, a Scotchbrite or equal pad works well to 
take the deposit off. You don't need to make the copper bright and shiny 
as new, a "Hershey bar" colored brown film is desirable. After a few 
minutes of carrying current, the film will stabilize and make reliable 
contact. It is not a perfect electrical connection, it does have a very 
low resistance, but it is stable, durable, and offers minimum friction 
to the brushes.  This applies to motor communtators and slip rings as well.

    Bruce Gentry, KA2IVY


On 6/17/21 14:03, Ralph Mowery wrote:
> >From what I read the copper and carbon from the brushes mix together and
> sort of make like a case hardening.
>   It should not be cleaned except for the normal oil and dust.
>
>   I don't know if you can even get any carbon tetrachloride any more.  Seems
> that I read that if you were around much of it and drank alcohol it could
> cause kidney failure.
>
> If I wanted to clean the dust and oil off of the ring segments I would use
> some 90% or better alcohol or electrical contact cleaner.
>
> Ralph ku4pt
>
>
> -----Original Message-----
> From: greenkeys-bounces at mailman.qth.net
> [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of John, W9DDD
> Sent: Thursday, June 17, 2021 1:37 PM
> To: Green Keys
> Subject: [GreenKeys] Model 14 TD distributor rings
>
> Best way to clean copper distributor ring segments?
>
> TM 11-2222 says carbon tetrachloride.  I'm not sure you can even buy
> that anymore.  I can remember in my youth that it was some pretty nasty
> stuff, but it worked great for cleaning.
>
> I seem to recall hearing a suggestion of using a pink pearl eraser, is
> that effective and/or OK?  Maybe depends on what's stuck to the copper
> rings?
>
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