FWIW... I recently had one of my Ham-Ms repaired.
Granted, it was severely overloaded, however it lasted more than a year
before croaking. I knew it had some teeth sheared off the ring gear (Al,
not steel) during hurricanes, however what I didn't expect was a comment
from the repair place, "Severe ball bearing depression in raceways, appears
to have been overloaded".
I was using a TB3, 4+ feet of mast inside of the tower, and all antenna/mast
weight (about 150lbs) on the rotor. - ???
73,
Blake N4GI
----- Original Message -----
From: "Jim Lux" <jimlux@earthlink.net>
To: "AA6DX - Mark" <aa6dx@arrl.net>; "TowerTalk" <TOWERTALK@contesting.com>
Sent: Monday, October 24, 2005 1:05 PM
Subject: Re: [TowerTalk] Bearings in Rotators
> At 08:19 AM 10/24/2005, AA6DX - Mark wrote:
>>Hello TTers ... just musing ... all the CDE / Hy-Gain rotators I have
>>taken
>>apart for the first time had room for a lot more ball bearings than came
>>with "stock". Years back, I went to the Bearings store locally and
>>stocked
>>up, and every time I put a rotator back together, I filled the race,
>>within
>>the plastic holder.
>>What is the consensus on this practice .. why would you NOT do that ..
>>and,
>>of course, why does NOT the manufacturer ... it seems like such a
>>no-brainer, but there must be a reason, other than $$$ ???? 73, Mark
>>AA6DX
>
> I suspect it makes NO difference for a low duty cycle application like a
> rotator.
>
> For things that continuously rotate, there are some peculiarities in how
> the balls roll along the race that make certain numbers of balls better
> than others. For instance, they tend to stack-up next to each other, then
> spread apart. This behavior results in different vibration patterns, some
> of which are "worse" than others for wear and life. I think that the
> number of balls and/or the filling ratio affects this. But this was for a
> space application with very precise tolerances and life requirements (not
> to mention running in a vacuum) with people who obsess about every little
> funny noise or wiggle in the torque curve.
>
> Some bearings have a spacer that holds all the balls (or rollers) at
> particular distances. Bearings that that have a consistent radial load
> might also perform better with certain numbers of balls in the race.
>
> Neither is probably the case for a rotator.
>
> You might try calling Fafnir or King Bearing and asking one of their
> applications engineers.
>
> I'm just guessing here.. It would be interesting to know the "real story".
>
> Jim, W6RMK
>
>
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and ask for Sherman, W2FLA.
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