[TowerTalk] Hindsight: Check your rotator bolts

[Roger (K8RI)]

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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