[TowerTalk] Hindsight: Check your rotator bolts

[Dick Green WC1M]

How do you get double nuts on a bolt that has no nuts to begin with? The
bolts screw into threads in the rotor casing. There's no way to double nut
them.

73, Dick WC1M

> -----Original Message-----
> From: Roger (K8RI) [mailto:K8RI-on-TowerTalk at tm.net]
> Sent: Friday, June 06, 2008 2:41 PM
> To: Barry Merrill
> Cc: jeremy at m2inc.com; 'Towertalk'; n5ya at n5ya.com
> Subject: Re: [TowerTalk] Hindsight: Check your rotator bolts
> 
> Just an added note:
> 
> I always use locking nuts (double nutting) on rotator mounting bolts
> unless they are the huge bolts as used by Prosistel.  I still use lock
> washers and locktite on the nuts.  I've never had a bolt come out of
> one
> of the Ham series of rotators or any other for that matter with this
> approach.  I don't know what size mounting bolts they use with the
> Orion
> but I'd guess this might apply here as well.
> 
> I'm not knocking safety wires. I fly airplanes and everything
> including
> oil filters is safety wired<:-)) However in less regulated and  much
> more environmentally friendly places than aircraft engine
> compartments,
> lock nuts (double nutting) is very effective.
> 
> 73
> 
> Roger (K8RI - ARRL Life Member)
> www.rogerhalstead.com
> N833R (World's oldest Debonair)
> 
> Barry Merrill wrote:
> > In 2003, I (actually, I watched, while Bill, N5YA,
> > and a 60 ton crane with 161 foot boom did the work)
> > installed a US Tower HDBX72 with a 24 foot mast,
> > and mounted a 2-el Cal AV 40 at the bottom and an
> > OB16-3 at the top, turned with an Orion RC2800
> > rotator, and have had zero problems and fantastic
> > results.
> >
> > Yesterday, after a day of 50mph winds, I noticed
> > that the antennas were rotated about 45 degrees,
> > and then discovered I could not rotate them.
> >
> > After Reading The Fine Manual and making the voltage
> > and resistance checks, which confirmed the motor
> > was fine, I called M2 support and received excellent
> > support, as Jeremy went thru the system and gave me
> > additional diagnostics, in particular, to connect an
> > ohmmeter to the counter wires, toggle the rotator
> > control, and see if reed switch opened and closed,
> > which it did, confirming the rotator electrics
> > were not the problem.
> >
> > Looking at the rotator from the shack (from the West)
> > I had seen nothing obvious, but when I then looked from
> > the North, I could now see that the rotator was no longer
> > in the center of the tower; the rotator was now flush
> > with the West side of the tower, and the mast was 2-3
> > inches off vertical at its bottom!!!
> >
> > Clearly, the bolts holding the rotator to the
> > tower plate had loosened.
> >
> > When I called Jeremy back to thank him for the
> > excellent diagnostics that eliminated elecrics
> > and to report what I had observed, he said that
> > this did, very rarely, happen, and that M2 now
> > offered a set of bolts that were pre-drilled for,
> > and were shipped with, safety wire, and he personally
> > packaged a set (only he and the Purchasing manager
> > were in the office, so he did it all!) and sent
> > them via UPS early AM delivery (promised for 8:30am,
> > the doorbell rang at 7:31am)!
> >
> > On the tower this morning, with the new bolts in hand,
> > before the wind kicked up again, Bill discovered
> > that two bolts were gone, one was still in place,
> > but loose, and one had enlarged its hole in the
> > tower plate so that it was above and sitting on
> > the plate, cocking the rotator.  Fortunatly,
> > with ropes on the boom for horizontal pull,
> > a jimmy bar in Bill's hand to lift, and a
> > comealong strap around the rotator body,
> > he was able to realign the rotator and its
> > holes, and the new bolts AND SAFETY WIREs were in
> > place with only about 2 hours tower time by Bill!
> >
> > With hindsight, it is now intuitively obvious to
> > the casual observer (or more certainly, casually
> > obvious to the intuitive observer), that I should
> > have had the rotator bolts checked before
> > five years had elapsed.
> >
> > And, now, with the awareness of the alternative
> > bolts and safety wires, even at $50.00 for the
> > package of six, I'd strongly recommend they
> > be purchased if you install the Orion, and
> > maybe for all rotators, and, periodically check
> > your bolts!
> >
> > Photos of the original tower installation are
> > in the lower left corner at http://www.mxg.com,
> > and you can see the load on the Orion is most
> > definitely non-trivial.
> >
> > 73,
> >
> > Barry, W5GN
> >
> > _______________________________________________
> >
> >
> >
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>