This message is to seek advice on the choice of thrust bearings. I have
checked the archives, but still need advice. I am just returning to TowerTalk
after a two year absence.
A current tower project for my new station includes a 120' PiRod tower that
will support two large antennas at 121' and 132' on a Chrome Molly mast. The
tower and mast are suitable to handle these antennas, with a safety margin.
The mast extends 7' into the top section of the tower. Three 1/2" steel
plates are welded into the structure of the top tower section at the 112', 116'
and 120' levels for the large ProSistel rotator and two 3" thrust bearings.
The
bearings are intended to handle both horizontal and vertical thrust, and
provide a stable mast support to permit removal of the rotator for maintenance.
The antennas are a full size 4-element K3LR 40m yagi (on a 48' boom and ~30
square foot wind load) and Force 12 Ultra 80m dipole (102' long and 11.5 square
foot wind load). The 80m dipole will be mounted parallel to the 40m boom to
spread the wind load more evenly.
The antennas and mast together weigh about 550 pounds.
Advice on the choice of thrust bearings would be appreciated. Low
maintenance is desired. Periodic service is not an issue, whereas replacement
would be
a challenging and costly project.
Jack Hammett, K4VV
k4vv@aol.com
_______________________________________________
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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