Hello Dino,
I wonder if you could post those pictures here so we can see them as
well??
I have two crank up towers and I am very concerned regarding that type
of failure!!
Many Thanks in Advance.
73,
Ted K2QMF
On Sat, 13 Oct 2012 16:45:27 -0700 "Dino Darling" <dino@kx6d.com> writes:
> I do have some photos of K6CF's failure and it is exactly as Skip
> mentioned. I'll get those to you. However, I don't think there is
> any
> real close-ups of the shaft. But you can CLEARLY see what broke!
>
> Skip, thanks for the clarification on Mike's failure being the
> shaft. I
> should have made that more clear in my first message. Again, this is
> the
> failure K6CF had too...same place also! Chris' tower used to belong
> to
> Jim Rafferty, N6RJ (SK). Jim would have purchased only the best at
> the
> time.
>
> As for the shaft failure; its unfortunate that they did not support
> the
> shaft on BOTH ends of the multigroove pully! I was going to mention
> blocking the first two sections together and taking that stress off
> of
> pulleys when not in use. US Tower does this on their military tower
> trailers and I've seen them on their towers sold to the Cell Phone
> companies. However, every failure has happened during transit that
> I'm
> aware of. Block it as you go if you are worried about it!
>
> If it was me, I'd modify the original 1" shaft models or replace it
> with
> a newer system. I think the modification would be easy enough
> though.
>
> Dino - KX6D
>
>
> -------- Original Message --------
> Subject: RE: [TowerTalk] Yet another worm gear box failure...
> From: "Scott MacKenzie" <kb0fhp@verizon.net>
> Date: Sat, October 13, 2012 10:46 am
> To: <KJ6Y@aol.com>, <dino@kx6d.com>, <towertalk@contesting.com>
>
>
> Any one have any quality photographs of the shaft failure? I am
> looking
> at
> photographs of the fracture surface. That should tell us the
> mechanism
> of
> failure.
>
> Scott
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf
> Of
> KJ6Y@aol.com
> Sent: Saturday, October 13, 2012 1:37 PM
> To: dino@kx6d.com; towertalk@contesting.com
> Subject: Re: [TowerTalk] Yet another worm gear box failure...
>
> Mike's tower sounds like the shaft broke and not a gearbox failure.
> On
> the older MD-750 motor drives, the shaft was 1 inch coming out of
> the
> gearbox. (Tristao and then US Tower). US Tower then went to a
> larger
> shaft, 1 1/4 or 1 1/2, don't remember which. Have not seen any of
> the
> newer ones fail.
> There is a lot of tension on that multi groove pulley, especially
> when
> hams have a tendency to overload their tower. It's not just wind
> load
> but
> weight. Those towers have a weight limit. Add it all up, mast,
> rotor,
> antennas, cables, etc and I'm sure you'll see more weight then you
> thought.
>
> Regular maintenance and inspections should be done.
>
> Skip, _KJ6Y_ (http://www.kj6y.com/)
> _Communications Service Co_
> (http://www.communicationsserviceco.com/)
> 818-887-3569
> _______________________________________________
>
>
>
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