[TowerTalk] One thrust bearing vs. two

[John E. Cleeve]

To resolve a similar problem with the head unit of my 60ft lattice tower, I
used a heavy duty roller thrust bearing, obtained from a scrapped heavy
truck in a vehicle scrap yard, at the top of the head unit, half way down I
fitted a well grease lubricated "Tufnol" plastic sleeve, bored out at 2
inches, in the vertically misaligned bearing support of the head unit. I
passed the 2 inch diameter, antenna support/rotation tube down through the
top thrust bearing and then through the "Tufnol" sleeve, and I coupled the
rotor, a Prositel worm drive unit, to the 2 inch tube, by means of a 6 inch
outside diameter rubber doughnut coupling, intended as a vehicle final drive
transmission coupling. There is a secure sleeve clamp around the antenna
support/rotation tube, between the antenna and the thrust bearing which
transfers the weight of the antenna system to the top of the thrust bearing.
73, John G3JVC.



-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of john at kk9a.com
Sent: 12 August 2009 15:44
To: towertalk at contesting.com
Cc: tod at k0to.us
Subject: Re: [TowerTalk] One thrust bearing vs. two

Tower top plates and rotator plates are not manufactured very precisely and
trying to line up two bearings plus your rotator bearing could be difficult.
If it's not lined up exactly it will cause some binding and add more stress
to your rotator and I don't see any benefit to having a lower bearing if you
are using an adequate rotator.   I think just using a top bearing and a
heavy duty rotator about 5' or more below would be a better choice.
 
John KK9A


To:  "'Tower Forum'" <towertalk at contesting.com> 
Subject:  [TowerTalk] One thrust bearing vs. two 
From:  "Tod -ID"
Date:  Tue, 11 Aug 2009 22:20:15 -0600 


I would be interested in 'opinions' on the need or utility for only one
thrust
bearing at the top of a tower vs. two thrust bearings one at the top and the
other several feet below the first.

Tod, K0TO

 

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