[TowerTalk] mast weight on the rotor or thrust bearing?

[John E. Cleeve]

Hello Dan,
That is exactly what I have done to my Strumech P60 tower. At the top of the 
head unit I have fitted a roller bearing which has a two inch bore, the 
bearing came from the back axle/wheel hub of a large truck. The two inch OD 
yagi support shaft passes through the bore of the bearing, with a collar on 
the yagi side, to transfer the weight of the antenna assembly to the inner 
of the bearing and thus via the bearing rollers, to the head unit of the 
tower. The rotor drive is then taken via a six inch diameter,  flexible 
rubber "doughnut" coupler, which in another life coupled the transmission 
drive shaft to the rear differential assembly of a Triumph sports car, and 
the rotor itself, is a worm drive Italian job. The rubber doughnut flexible 
coupler does a great job in absorbing the initial mechanical shock of 
gusting wind conditions, which I have found, in the past, eventually 
strips/breaks the teeth of the conventional spur geared 
rotators..........sincerely, John G3JVC.
----- Original Message ----- 


From: "Dan Zimmerman N3OX" <n3ox at n3ox.net>
To: <towertalk at contesting.com>
Sent: Monday, November 20, 2006 6:30 AM
Subject: Re: [TowerTalk] mast weight on the rotor or thrust bearing?


> >Actually I think the old, cheap, TV towers had it right. They had a 
> >sleeve
>>at the top and that served as a "side" thrust bearing.
>
> I'm wondering something, as someone who's spent graduate school
> building big machines, but  also someone who's never done anything
> with a real tower.
>
> It seems to me that a good approach would be a tower section with two
> good bearings mounted in it, one for radial forces only (the top one)
> and one for axial and radial forces on the bottom, and then the
> rotator would JUST rotate and brake, with a flexible coupler between
> the rotator shaft and the mast.
>
> Are people doing it, and I just don't know, or is there some practical
> advantage to having your lower bearing be custom-built into the
> rotator housing?
>
> 73 from an eventual tower owner,
> Dan
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