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Re: [TowerTalk] Mast and Thrust Bearing questions

To: Christopher J Galbraith <>,towertalk <>
Subject: Re: [TowerTalk] Mast and Thrust Bearing questions
From: bob finger <>
Date: Fri, 07 Jul 2006 15:54:21 -0400
List-post: <>
Chris:  Rule of thumb is 1/3 of the mast inside the is a rule 
you should follow.  Rohn TB3 thrust bearings will last a very long time 
if you DONOT lubricate them.  If you do, then expect failure.  They are 
designed to run dry and unless you rotate the beams constantly ie 24 
hours a day every day then it should last you a lifetime.  It is a good 
idea to put a boot on the mast to keep water out of the bearing....look 
for a rubber collar in the plumbing section.  If you don't have ice 
don't worry about it. 

A second lower thrust bearing is a good idea if you ever need to pull 
the rotator.  It need not be a thrust bearing tho. You want to 
eliiminate side movement is all.  If you use a second TB3 then do not 
tighten the capture nuts except when you are lifting the mast to pull 
the rotator.  It is almost impossible to get two thrust bearings aligned 
such that there is no twist.  Leaving the lower one loose keeps lots of 
trouble from happening. 

A second rotator plate with the mast running through the hole and a 
piece of oak with a hole drilled about 1/8 inch larger than the mast and 
bolted to the shelf will do the trick for far less money.  When you need 
to pull the rotator just put a U bolt and saddle on the mast and resting 
on the top of the oak to keep it from slipping down while the rotator is 

Good luck and do it all safely.  73 bob de w9ge

Christopher J Galbraith wrote:


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