A thrust bearing takes the weight and the downward moment off the rotator.
I have several commercial Fafnir bearings for schedule 40 water pipe (1.9"),
2" steel mast, and 2 1/4 in steel mast. You "MUST" use the size that
matches your mast. Using a size too big means that even if you adjust the
set screw you still do not have an effective bearing especially for the
downward moment. The WD9IIX ladder mast I have is 2 1/4" so I use a
matching bearing.
The best protection for any rotor is to have both a thrust bearing and a
sleeve bearing. I have an old paper written by Lou Tristao (presented at
some hamvention). He explains why the Tristao towers (Now US Tower) have a
sleeve bearing and why he advises everyone to add a trust bearing at the top
of the tower, too. The "so called" pointed top on the Rohn top sections
also act as a sleeve bearing. The sleeve bearing holds the mast in a
straight up position with regard to the rotator even in a strong wind. Thus
giving protection from side moments.
Lou explains why this is so by using college static and dynamic equations.
Using the old Tristao tower with the trust bearing I have used a T2X since
1979 to rotate multiple beams on the tower. Now if I could control the
bees, trees, and white lubricant that goes chalky every 5 years (I have a
spare T2X, too)..........
Dave K4JRB
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