Sorry, in my previous post I should have mentioned:
My top "thrust bearing" is actually what N4NM calls a "pointy-top"... a tube
attached to the top tower section thru which the mast passes... which acts as a
guide. Inside the tube, the mast is protected to some degree against chafing by
a thin polyethylene sheet wrapped around the mast as a bearing, plus plenty of
grease. I used rubber plumbing adaptors ("Furnco's") as grease retainers top &
bottom... one end hose-clamped to the mast and the other end a loose fit on the
guide tube. But the important point is that nearly all the weight is supported
by those double-saddled muffler clamps sitting on the REAL thrust bearing
that's between the guide tube and the rotator. I don't even use the setscrews,
so scoring, etc, is not an issue. I would think that using two actual TB's
would work as well.
Rotator removal is not a problem because my tower tilts over, but if it didn't
the TB taking the weight would allow me to R&R the rotator without disturbing
the mast or antennas.
73, Jerry K3BZ
----- Original Message -----
From: kb9cry@comcast.net
To: Noel ; towertalk@contesting.com
Sent: Thursday, July 22, 2004 2:46 PM
Subject: RE: [TowerTalk] Re: Thrust bearing
I have TB-3 on my towers and what I do is set the mast down into and resting
on the rotator. I center the mast in the thrust bearing and tighten the collar
screws, really just to keep it centered. I then install a small SS pipe clamp
onto the mast and move it down the mast so it is up against the top of the
bearing. I then install the antenna. My assumption is that some of the
additional load from the antenna is being borne by the TB. Seems to work for
me. If I need to remove the rotator, I've installed another pipe clamp up the
mast above the top bearing plate and used a small scissors jack to jack the
mast assembly up and out of the rotator. On the new tower I might attach a
come-along to a clamp attached on the mast just above the rotator and jack it
up that way. Phil KB9CRY
-------------- Original message --------------
> Agreed with everthing except the statement. "...Then make sure the
> collar can rotate around the mast without binding".. Seems to defeat the
> point of having a thrust bearing? Why not have just a collar then? I
> think the bolts in the thrust bearing should be tightly holding the mast
> or at least very snug. Not bearing weight but enough to support any
> lateral movement. Your method would cause the bolts to eventually scar
> the mast even though you say the clearance is minimal, unless one used
> shims.
>
> I'm curious haw many people who utilize thrust bearings, allow the
> bearing to "rotate around the mast" or make sure the mast and bearing
> are tight and rotate together?
>
>
> Noel
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather
> Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions
> and ask for Sherman, W2FLA.
>
> _______________________________________________
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
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