Unlubricated bearings? Maybe the reason you are wearing out the races. I
use Moly grease on all of mine, no problems yet. Every bearing needs
lubrication, even old windmills from 100 years ago have oilers, and windmills
only
turn at about 75 rpm. Where I live dust and dirt above 50 feet is not a
problem, maybe in West Texas or Arizona the big dust storms could deposit
enough to make a difference.
The grease would not make a negative difference in the grit problem.
Once grit gets into the races the damage is done, grease or no grease. No way
to get the grit back out either way. Actually the grease would help keep
the grit out. Once a bearing is put through several rotations, excess grease
is forced out through the races. There is no way to get this grease back
into the bearings. There is no grease pump to move grease back onto the
bearing surfaces.This is why you repack wheel bearings. The excess grease can
act as a semi-seal for the races.
Also the only way to get grit into this bearing is for it to blow in an
upward direction through the small crack between the two halves. Grease in the
bearing would prevent airflow through the bearing. No airflow, no grit.
FWIW,
Marty ab5gu
In a message dated 5/18/2010 7:34:30 A.M. Central Daylight Time,
K7LXC@aol.com writes:
In a message dated 5/17/2010 6:18:19 P.M. Pacific Daylight Time,
towertalk-request@contesting.com writes:
> Hi TTers,
I got that Rohn 45 tilt-over down and home last week. In remarkably good
condition. Only thing I wondering about is the TB3 thrust bearing and how
to
lubricate it. It turns freely but has a notable rumbling sound and feel
to
it. I notice at the bottom of the inside shaft area where to mast passes
through, is a recessed Allan head fitting/plug. Would this be the place
to
remove and squirt in some white grease? And then replace the plug?
Removal of the Allen screw allows you to remove the ball bearings and
then take the bearing apart.
This bearing should NOT be lubricated with anything. All that does is
give airborne grit and crud a place to attach to, thus accelerating the
failure of the bearing. The bearings are not sealed so it's easy for junk
to
get into the bearings and races.
The TB-3 (and TB-4) are both aluminum races with steel ball bearings.
It is very common for older TB's to have the rumbling you describe since
in
wind gusts, the steel bearings can get pounded into the softer aluminum
races. This means the bearing is on its last legs. I wouldn't reinstall
it.
Well, if you were just going to use it as a bushing without tightening
the 3
bolts, it'd last for years. The actual value of a thrust bearing is the
subject of some conjecture since most or all of the weight of a mast and
antenna array should be on the rotator.
Cheers,
Steve K7LXC
TOWER TECH
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