[TowerTalk] Lift cable, Galv Steel, vs Stainless

[Al Williams]

I agree with w4hy.  One of the reasons that I selected the LM470 was that 
Joel of First Call claimed that there were two cables so that the tower 
would not collapse if one broke.  This tower was built by the short lived 
Paragon company and unless other manufacturers versions are rigged 
differently they too will collapse if the main pull up cable breaks.

I would appreciate very much if k0dan would explain exactly which cable 
broke etc.

k7puc

PS  This was not the only claim by Joel that wasn't true!

----- Original Message ----- 
From: "Julio Peralta" <jperalta at tampabay.rr.com>
To: <towertalk at contesting.com>
Sent: Monday, October 03, 2005 3:46 AM
Subject: Re: [TowerTalk] Lift cable, Galv Steel, vs Stainless


> Pat I don't think this is entirely correct. If the main pull up cable
> were to break the 2nd section would fall bring the 3rd and 4th inner
> sections with it. The pull down cable runs from the base of the tower to
> the bottom of the 4th or top section and serves to help the tower
> retract in conditions where the wind is blowing and may bind the
> sections. The pull down cable will not support the weight of the tower.
> Not because it's not strong enough but because it's not rigged to do so.
>
> I think I'm right about this can someone else confirm my comments?
>
> Julio, W4HY
>
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of k0dan
> Sent: Sunday, October 02, 2005 10:55 PM
> To: Pat Barthelow; towertalk at contesting.com
> Subject: Re: [TowerTalk] Lift cable, Galv Steel, vs Stainless
>
> 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 at hotmail.com>
> To: <towertalk at 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 at 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.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> _______________________________________________
>
> 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.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>