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Rohn shackles/T-Bars

To: <>
Subject: Rohn shackles/T-Bars
From: (sawyers)
Date: Thu, 06 Jun 96 07:47:27 cst
You MAY - and I repeat MAY - be seeing a difference in the "rated strength" 
methods of two different industries.

1/4" EHS is rated at its minimum ultimate breaking strength i.e. 6700 #. It 
is known in the tower industry that we apply a "factor of safety" of two to 
the design load on the guys per EIA-222. That is if the tower and antennas 
put a 3000" load on the guy wire we know we must select a guy wire that 
will hold at least 6000#.

Shackles are used in the construction industry. The rating that you MAY be 
seeing is "safe working load". This usually has a "safety factor" of 3 to 5 
applied to the ultimate breaking strength. It depends on the manufacturer 
and the standard under which the shackle is rated. This would say that the 
shackle COULD HAVE an ultimate breaking strength of 6000# to 10,000#. You 
need to look at the manufacturer's catalog, or call the manufacturer to 
determine exactly what factor of safety is included in their rating.

You have to understand the rating system to understand what they are trying 
to tell you.

This is kind of like how some people rate towers in ads, only in reverse. 

de n0yvy steve

Disclaimer: I and my company agree on at least one thing: My opinions are 
my own.

______________________________ Reply Separator _________________________________
Subject: Rohn shackles/T-Bars
Author:  AA7BG Matt Trott <> at ccmgw1
To: <>
Date:    6/4/96 3:29 PM

Can anyone tell me why Rohn would advise (in their catalog) using 3/8 
shackles with their torque bar guy package.  I guess my pea-brain just 
doesn't understand how some of this stuff is rated. Let's say you're using 
1/4" EHS guy cable. This is rated at 6700#. Now if you use the 3/8 shackles 
at the torque bars isn't this a "weak" link.  Near as I have been able to 
find out, these shackles are "rated" at 2000#! I've tried 1/2" shackles, but 
the pins are too big to go thru the hole in the torque bar.  The reason I 
don't just slip the thimble thru the torque bar is that I'm using P-stran 
which requires oversize thimbles.  I really, really, really doubt that the 
3/8" thimbles would ever break, but I just don't understand the rating 
differentials of 6700# vs. 2000#. It just bugs me, man. 
AA7BG      Matt Trott 

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