[TowerTalk] Re: Thrust bearing

[K4FJ at aol.com]

In a message dated 7/22/2004 3:50:29 PM Eastern Standard Time,  k3bz at arrl.net 
writes:

I use  two thrust bearings, one at the top and one a couple of feet down the 
mast.  The rotator is a couple of feet below the bottom TB. The top TB is 
merely a  guide; the bottom TB supports all (or nearly all) the weight of the mast 
and  antennas via two opposing "double-saddled" muffler clamps on the mast. 
The  mast doesn't actually bear much on the rotator... the rotator merely grips 
the  mast and turns it. I figure the less weight that bears on the rotator, 
the  longer it will last.... and TB's are cheaper than rotators!  I do have  
the mast pinned to the rotator, however, as the Yaesu rotator provides for  
pinning. 
This is my first tower, but this arrangement seems to work A-OK  for me. I've 
had no slipping or other problems with it.

73,  Jerry  K3BZ



Jerry's approach using two bearings (or a thrust bearing and guide) before  
the mast gets to the rotator is the preferred method.  You will realize it  the 
first time you want to change out a broken rotator.  However, it you  choose 
to use a Rohn top section with the snorkel top, you can get away with a  
single thrust bearing on a plate above the rotor.  The snorkel is your  guide.  A 
bit harder to get to the antenna attachment point but not  bad.
 
73, Steve