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
----- 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.
>
> _______________________________________________
> 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
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
http://lists.contesting.com/mailman/listinfo/towertalk
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