This is very simular to the one UST uses. With the exception that the
mast diameter is 2 1/16" and has a 2 hole bolt pattern. I wonder if
the 2" hole would be too small for some masts?
Julio, W4HY
----- Original Message -----
From: ersmar@comcast.net
Date: Friday, May 12, 2006 11:46 pm
Subject: Re: [TowerTalk] Thrust bearing shot
To: K8RI on Tower talk <k8ri-tower@charter.net>,
TOWERTALK@contesting.com
> Roger:
>
> I used a self-centering industrial bearing at the top of my
> tower, similar to:
> http://www.applied.com/catalog/ma/catalog.do?e=10&s=2000776&r=0 .
> I lube it once each year with marine grease. It cost about what a
> TB-3 would cost ($70 in 2001.) Because it's self-centering, it
> will accommodate up to a +/- 2 degree misalignment of the mast and
> bearing centerlines. FWIW.
>
> 73 de
> Gene Smar AD3F
>
>
> -------------- Original message ----------------------
> From: "K8RI on Tower talk" <k8ri-tower@charter.net>
> > I thought I'd pass on some information.
> >
> > It seems like even with care planning for problems when pushing
> the limits
> > the problems turn up where we don't expect them.
> >
> > I'm running a 97 foot ROHN 45G. The tribander is supported just
> above the
> > top of the tower on a 24' long, 2" structural steel tube with
> 1/4 wall over
> > an 1 1/2 tube with 1/4 inch wall made up of two sections
> totaling about 44
> > feet. So the center section has essentially a 1/2 inch wall,
> supports the
> > TH-5 at 100' while the 7L C3i 6 meter beam at 115' is mounted on
> the 1 1/2
> > pipe right at the top of the 2". The 144/440 array is 12 feet
> above the
> > 6-meter antenna at roughly 127'.
> >
> > The mast is supported by a TB-3 at the top of the tower with a
> second TB-3
> > about 12 feet below the top of the tower that just keeps the
> mast centered
> > with the rotator (PST-61) mounted at 17' below the top of the
tower.
> >
> > I knew the leverage of the tall mast above the top of the tower
> would create
> > some pretty strong forces at the top of the tower, but after
> about 4 years
> > with lots of severe winds up here, the races in the TB-3 have
> worn to the
> > point where the upper race is setting right down on the washers
> for the
> > mounting bolts. This is causing the bearing to bind to the
> point the PST-61
> > is unable to turn the mast.
> >
> > It appears as if I'm going to need to replace the upper bearing
> with a
> > pillow block arrangement of some sort with a fairly close fit.
> If it
> > weren't for the massive side forces created by the leverage I'd
> use oil
> > soaked hard wood, but I think I'm going to need to get a split
> block of
> > steel or Aluminum machined to fit which will give a large
> surface area to
> > support the side forces without undue wear. I sure could use
> that milling
> > machine I was going to purchase before the market tanked back
> around the
> > turn of the century.
> >
> > And the day before I was going to order some LMR-600 and
> fittings for the
> > pigtails the price went up. <sheesh>
> >
> > Roger Halstead (K8RI and ARRL 40 year Life Member)
> > N833R - World's oldest Debonair CD-2
> > www.rogerhalstead.com
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> _______________________________________________
>
>
>
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