[ARC5] Dynamotor Maintenance - Graphite as Lube

[Christopher Bowne]

Re graphite as lube, around 1980, ARCO marketed a motor oil called ARCO 
Graphite, which contained graphite as an additive.  I tried it in my 1977 
Mercury Bobcat 2.3L wagon's engine. Stopped using it after only a few thousand 
miles because it badly gummed up the valve lifters and made them clatter, 
problem went away after it took that stuff out of the engine.  Still have black 
oil stains on the cinder block knee wall in my garage where oil flew off the OHC 
cam lobes when I made the mistake of trying to listen with the engine running 
for the stuck lifters with the OHC cam cover removed!  Had done that  before on 
OHV engines, did not consider how much oil can fly off a cam.  The oil was 
already black fresh out of the can.  The stuff  disappeared from the market a 
short time later, perhaps due to other people having similar problems to mine.




________________________________
From: Mike Hanz <aaf-radio-1 at aafradio.org>
To: jfor at quikus.com
Cc: arc5 at mailman.qth.net
Sent: Sun, January 20, 2013 8:28:17 AM
Subject: Re: [ARC5] Dynamotor Maintenance

As both Roy and Ken point out, there are many forms of graphite, John.  I was 
specifically referring to carbon dust from the brushes, which is a harder 
material than pure graphite.  Roy's reference to a clay material rings a bell 
with me too.  Perhaps abrasive was a stronger word than needed - it has a 
polishing action that will wear high speed bearings out fairly quickly in steady 
service.

I am frequently reminded how much caveating (or maybe cavitation? :-) ) is 
needed when we talk about stuff on this list.  E-mail isn't the greatest medium 
for covering complex subjects.  Here are some additional caveats that came to 
mind after reading the morning traffic:

1)  The primary subject has been small dynamotors which had no forced 
ventilation, unlike the larger dynamotors (ART-13 and the like, as well as most 
of the rotary inverters by the end of the war.)  In that equipment, an open 
architecture with fans and impellers on the shaft blow quite a blast of air past 
the commutators and reduce the carbon dust problem to a degree.  The Navy took 
it to the logical extreme with shipboard equipment, a great deal of which had no 
end bell covers at all.  Just don't stick your fingers in the rotating machinery 
to test it...OSHA wasn't there to fiddle with the situation.

2)  In the late 1950s, bearing seals had vastly improved because of new 
materials, and I have an NOS DY-17A here from Robert Downs whose bearings has no 
capability of being serviced.  Like any machine, it needs to be cleaned and 
check occasionally, but it should have a longer time between servicing than the 
WWII counterparts.

3)  In the last few months, a list member sent me some photos of an amazing 
amount of wear on a commutator - the brushes had carved a deep U shaped valley 
across the commutator, and he said it was still running fine.  It's another 
reason never to say never about something.  There are always example of extreme 
punishment endured without whimpering.

4)  In rereading what I wrote last night, I want to make it absolutely crystal 
clear that I did not mean to reflect any disrespect for Wayne, nor suggest that 
he was wrong in any way.  I was grateful that he took the time to post the 
fascinating differences between the two manual revisions, and he obviously knows 
what he is doing -  his work on a dynamotor using "magneto grease" (small 
bearing grease) is a classic way of doing a job the "correct way" (if there is 
such a thing.  Some folks bristle at the thought...)  My closing thoughts were 
directed toward some stuff I've read on the ham radio reflectors, not to any of 
the inhabitants of this list - we collectively seem to have a lot more knowledge 
than the folks on those lists.

I hope that everyone was a wonderful Sunday,
- Mike  KC4TOS

On 1/19/2013 11:15 PM, J. Forster wrote:
> I am puzzled by your statement that Graphite is abrasive, especially since
> it is widely used as a dry lubricant.
> Messy, for sure, but abrasive?
> 
> -John
> 
> ==============
>> 3)  Clearly this was a non-sustainable maintenance policy.  While the
>> binder doesn't wear out, and you can renew the viscosity level of the
>> lubricating oil that does the essential work in the bearing, you cannot
>> keep contaminants out, and carbon dust from the brushes is one of the
>> most abrasive contaminants around.

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