[TowerTalk] One thrust bearing vs. two

[K7LXC at aol.com]

In a message dated 8/12/2009 8:12:01 A.M. Pacific Daylight Time,  
towertalk-request at contesting.com writes:

>  I would be interested in 'opinions' on the need or  utility for only one 
thrust
bearing at the top of a tower vs. two thrust  bearings one at the top and 
the
other several feet below the  first.


        The alleged purpose of the  middle thrust bearing is to hold the 
mast vertically to aid in rotator  replacement. You don't need a middle 
bearing - all you have to do is capture the  mast. You can do that with a rotator 
plate sans bearing or fabricate a mast  holder made from a couple of pieces 
of angle iron and U-bolts. You just install  it when you need it. 
 
        A mid thrust bearing can  potentially add more bind in the 
rotator/mast system. The tolerances are  relatively large and some misalignment is 
common. 
 
Cheers,
Steve    K7LXC
TOWER TECH -
Professional tower services for hams
Cell: 206-890-4188
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