[TowerTalk] Thrust Bearing adjustment

Jim Thomson jim.thom at telus.net
Thu Apr 10 19:40:58 EDT 2014

Date: Thu, 10 Apr 2014 13:46:43 -0700 (PDT)
From: Mike Fahmie <wa6zty at yahoo.com>
To: Tower Talk <towertalk at contesting.com>
Subject: [TowerTalk] Thrust Bearing adjustment

I'm about to raise a 72' US Tower equipped with a pair of TB2US thrust bearings spaced about 3'.? I'll be using a TailTwister2 Rotator.? Is there a procedure for centering these components to preclude binding?

I doubt there is a way to make the two bearings share the vertical load, so which one should I choose.? I'm thinking that the top bearing should take the load and use the lower bearing to stabilize the mast laterally.


##  DON’T  use the set screws in the 2nd ..lower  TB2US.   I use two of the same bearings on my UST-HDX-689.   Lower bearing is 4 foot down from the top.   PP rotor is 6 foot down from the very top.   2 foot between
lower bearing and rotor.    The tb2us uses an eliptical locking ring.   It will either lock CW..or CCW.    Just make sure u know which way it went on.   A small recessed partial hole on the locking collare is whacked with a drift punch..to lock the ring.

##  so leave the bottom bearing loose....so it only takes the lateral load..that’s it.    You can only ever line up 2 things...not 3.   So with the 2 bearings +  rotor.... it becomes the top bearing and rotor...never the middle
bearing.    And I sure as hell would not rely on that top double plate and cylinder  on the UST towers to take all the load...esp when rotor removed..mast elevated a bit...and only the top bearing used.  Not with
a 20 ft mast.... with  14 ft above the tower..and 6 foot into the tower.     Which becomes   15 ft above and 5 ft below..when rotor is removed.   The double plate at  the top of the tower and cylinder has a set screw..used to lock the mast  when rotor is removed.   I would supplement that   with some temp u bolts on the mast +  angle steel..so the mast  doesn’t rotate in a high wind with rotor removed.

Jim  VE7RF

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