[TowerTalk] Thrust Bearing

[Mike]

There is now way that a small Set Screw on the locking ring provides against any downward force for moment.  Think about it, 200 lbs of antenna maybe and 90 pounds of mast.  I certainly would not be under the mast removing the rotator and hoping the set screw would hold.  The Rotator (even cheap ones) are able to handle heavy vertical loads.

Mike

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Ed Williams
Sent: Saturday, November 24, 2012 11:36 PM
To: 'Wilson Lamb'; 'towertalk'
Subject: Re: [TowerTalk] Thrust Bearing

Hi Wilson,

True that the thrust bearing provides side support, but most that I have seen also provide down force protection as well.  Mine has a locking ring at the top of the bearing.  It is non-circular to provide for centering the mast in the bearing, and a Allen key to lock the mast from dropping thus removing the down force onto the rotator thus a real side and downward thrust bearing.

73, de KN4KL/KG4KL ed 

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Wilson Lamb
Sent: Sunday, November 25, 2012 12:20 PM
To: towertalk
Subject: [TowerTalk] Thrust Bearing

OK, I�m old.
I keep seeing the trem �thrust bearing� used for the bearing at the top of towers, to take the side load of the mast.
AFAIK, thrust bearings take AXIAL loads, the load of the mast/antenna going down the mast toward the rotor.
Car crankshafts have thrust bearings, ship propshafts have thrust bearings, etc, so why should we be different?
Yes, thrust and radially loaded bearings can be built together, as in a car engine, but that�s not what we have when a mast goes through a sleeve.
So am I behind the times?  Do tower people speak their own language, or what??

The Ham IV has 96 ball bearing balls, but they don�t bother to rate it for axial load.
This little TV rotor http://96.9.26.247/schemi/ACC_rotator/NTC_ECG_rotator_spec.pdf , however, is rated for 100lb axial load, so I think the most of us with a tribander and Ham XX won�t have a thrust problem.

Wilson
W4BOH
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