Hi All,
Yes the Tri-ex/Rohn TB-3 Thrust bearing is ruff and has always been ruff on
turning. And Yes the W-51 had only three mounting holes for the 4 hole
TB-3 Bearing. My LM470 (2@) both have a 4 hole mounting but the W-51 had
only a 3 hole mounting.
I took my TB-3's that I recently purchased from Tessco and did the
following to make them turn easier. Yes, fellows, I know that the
rotational speed of an amateur array is only LESS than 1 RPM, but christ,
it's kinda like dragging a perfectly good GUN down the sidewalk because you
are only walking 10' and the sidewalk looks smooth..
The TB-3 has steel bearings and an aluminum casing, just a little bit of
dis-similiar metal problem. The bearing rust and the aluminum ozidizes and
flakes away. Living 2 miles from the Pacific Ocean I see lots of corrosion
from the salt air and 40" of rain per year.
Here's what you do-------
1. Dis-assemble the bearing.
2. Drill the top half of the bearing assembly for a grease fitting and
then cross drill the top section to facilitate the grease getting to
the bearings inside.
3. Re-assemble the assembly and GREASE the bearing with a good quality BOAT
wheel bearing grease, (the kind you grease your
boat trailer with because you roll the trailer wheels into and under
the water when you launch your 'other hobby'. You know the
story, the only difference between men and boys is the price of their
toys!!)
4. Cut a piece of flexible plastic to form a cone that can be clamped to
the mast above the bearing to cover the bearing.
I've done this to both my TB-3's and yes, you have to crank the tower down
to do it, but they lived for 15 years the last time...
I've got some pictures if you would like to see them, let me know
Bob Smith
A.R.S NA6T
ARRL Life Member
Fort Bragg, California 95437
"On The Air-Conditioned Mendocino Coast, In REAL Northern California"
No trees were destroyed in the sending of this message.
However, a large number of electrons were terribly inconvenienced.
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