In a message dated 7/22/2004 3:50:29 PM Eastern Standard Time, k3bz@arrl.net
writes:
I use two thrust bearings, one at the top and one a couple of feet down the
mast. The rotator is a couple of feet below the bottom TB. The top TB is
merely a guide; the bottom TB supports all (or nearly all) the weight of the
mast
and antennas via two opposing "double-saddled" muffler clamps on the mast.
The mast doesn't actually bear much on the rotator... the rotator merely grips
the mast and turns it. I figure the less weight that bears on the rotator,
the longer it will last.... and TB's are cheaper than rotators! I do have
the mast pinned to the rotator, however, as the Yaesu rotator provides for
pinning.
This is my first tower, but this arrangement seems to work A-OK for me. I've
had no slipping or other problems with it.
73, Jerry K3BZ
Jerry's approach using two bearings (or a thrust bearing and guide) before
the mast gets to the rotator is the preferred method. You will realize it the
first time you want to change out a broken rotator. However, it you choose
to use a Rohn top section with the snorkel top, you can get away with a
single thrust bearing on a plate above the rotor. The snorkel is your guide.
A
bit harder to get to the antenna attachment point but not bad.
73, Steve
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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