[ARC5] ARC receiver dynamotor screw seals

[Neil Barnett]

Dynamotors are scarce here, and I've never seen
or heard of one with seals fitted to the cover screws.
I may be way off base with this suggestion but here
goes:

Service technicians in the field may have been in
the habit of overlubricating the bearings, causing
premature failure of the brushes.
Perhaps sealed bearings were introduced late in the
war, giving a much longer and more predictable
service interval.
The late date stamps reported by Clare (below)
tend to support the suggestion.

Is it possible that the sealed cover screws indicate
that the dynamotor was shipped with the new type
bearings, and that the service interval was different
from that of an ordinary unit?  Sealed bearings
would be discarded and replaced at say 2,000 hrs,
versus a re-lube at 1,000 hours for the non-sealed
type.

Its been more than 30 years since I last inspected
the insides of a dynamotor, and I paid no attention
to the type of bearing at the time.

73 de Neil ZL1ANM
in Auckland.


----- Original Message ----- 
From: "Clarence M. Owens" <Owens_Clarence_M at cat.com>
To: <ARC5 at mailman.qth.net>
Sent: Thursday, April 21, 2005 6:27 AM
Subject: [ARC5] ARC receiver dynamotor screw seals


>
>
>
>
> Hi All,
>
> I ran into something unfamiliar this weekend.  I bought four ARC receiver
> dynamotors, type DY-2A/ARR-2.  Nothing too special there, but three of 
> them
> had all four cover screws secured by lead seals.  The seals have the ARC
> logo molded into them.  The fourth dynamotor had them on one end only so I
> decided to open the seals on that one.  Swaged cups hold the cute little
> lead seals over the screws.  In order to service the dynamotors you have 
> to
> destroy the cups and seals and then drill out the back of the cups so they
> can be removed.  I suppose the chances of ever having to change brushes or
> grease before the plane was destroyed were very slight during the War so
> ease of maintenance was not a real concern back then.
>
> The Navy date stamps on the dynamotors are from 1943 and 1944.  Were these
> seals applied as an alternate to safety wire?  Were they common?  I have
> over a dozen other command receiver dynamotors and none of them have seals
> like these.
>
> Just curious....
>
> Clare Owens  N2RJB
>
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