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Bearing for Pointy-Top Towers

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Subject: Bearing for Pointy-Top Towers
From: (
Date: Wed, 15 Jan 1997 12:27:13 -0500 (EST)
In a message dated 97-01-14 22:51:39 EST, you write:

>From what you are saying, then, is that it is okay to cinch down the
>thrust bearing on the mast to take the vertical load?  My impression
>was that the prevailing thought was that the rotor takes the vertical 
>load and the thrust bearing keeps it all vertical. 

Hi, Dale --

    Well, yes, that's what you're supposed to do.  

    The purpose of the thrust bearing is two-fold.  First, it takes most of
the wind induced side load exerted on the antennas/mast; the side thrust.

    Second, it also takes (much) of the vertical dead weight of the
aforementioned antenna/mast system.  In theory, this is supposed to be easier
on the rotator as the thrust bearing takes much or all of the weight.  Then
all the rotator has to do is turn the antennas.  

     While all rotators have a vertical weight capacity (i.e. the Orion 2800
will handle 1800 pounds of vertical load), the subject of exactly HOW MUCH
vertical load to have is undefined.  All rotators are designed to have some
"load" on them for proper operation.  This seats the bearings in the races
properly, etc.  But I haven't been able to find out what the correct AMOUNT
of pre-load is. Then the question, if we decide that pre-load is desireable,
is how do we measure it?   If any has some pithy comments in regard to this
topic, I'd appreciate hearing about it.  
>Seattle is dogging my trail...we have had four nights of sub-32 degree
>temperatures since I have been back.  I don't like this one bit. 

    Out of the refrigerator and into the freezer, eh?

73,  Steve   K7LXC

    TOWER TECH -- professional tower supplies and services for amateurs

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