Pat:
I can't address the M.E. issues you bring up, but is the engineer in
question aware that the Tri-Ex LM series uses redundant cables?
That is, there is a pull-up and a pull-down cable, but if one were to break,
the other one still does hold up the structure, and will raise/lower it for
emergency purposes? (I know, I have had one cable fail...came off pulley and
got pinched/broke, and I was still able to safely control the tower.)
Based on my experiences here (west-central Missouri) I would definitely try
for the S.S. cable, as corrosion and contamination are definitely issues
with galvanized, especially over time.
I have restrung the cables on my LM470D, and while it can be done, it is a
rather lengthy and tiring process. Anything which will keep the tower safe,
while extending its maintenance periods, is worth the investment.
GL & 73
Dan
K0DAN
----- Original Message -----
From: "Pat Barthelow" <aa6eg@hotmail.com>
To: <towertalk@contesting.com>
Sent: Sunday, October 02, 2005 4:03 PM
Subject: [TowerTalk] Lift cable, Galv Steel, vs Stainless
>
> I am reviewing the engineering calculations for a Triex LM 354 tower, a
> paper copy of which is signed and sealed by a Civll Engineer. The 19 page
> doc, gives the uninitiated a small, insight into the calculations,
including
> the mathematical equations used, for all aspects of mechanical engineering
> of that particular tower. One calcualation, that of loads on, and thus
> tensile strength requirements of, the lift cable, I am examining for
insight
> to viability of stainless steel lift cable substitute for galvanized steel
> iin hopes of eliminating worries of deterioration due to corrosion.
> The LIFT CABLE STRESS Calcs:
> (Quote)
> 1/4 x 7 x 19 galv aircraft cable
> Maximum Breaking Strenght = 7000 lbs
> Factor of Safety = 7000/540 = 13.0 >3.0
> (Unquote)
>
> (where 540 is a calculated value of tension on the bottom run of the
cable.)
>
> If I interpret this line correctly, is it saying:
>
> Factor of Safety is 13.0 which is much greater than a minimum factor of
> safety of 3, therefore easily passes.
>
> Is this an good interpretation of what the Engineer writes?
> If so, then stainless steel lift cable, which according to most wire
tables,
> has only slightly less tensile stregth than similar galvanized steel
cable,
> should also easily meet requirements for lift cable for ham towers..
> Or am I, as an unprofessional observer missing or assuming too much?
> Tnx...
> 73, DX, de Pat Barthelow AA6EG aa6eg@hotmail.com
>
>
> _______________________________________________
>
> 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.
>
> _______________________________________________
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>
_______________________________________________
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.
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