[TowerTalk] Guy Cable

[Eric Scace K3NA]

   "Wire rope" is also a technical term used in the rigging industry.  
It covers all forms of steel cable that have been discussed in this 
email thread, including "aircraft cable".

   Choosing a wire rope design for cranking up/down a tower is different 
from choosing a wire rope design for guying a fixed tower.  These are 
different applications that have different requirements.  Choosing the 
right wire rope for cranking up a tower involves a lot more tradeoffs 
(rope material, sheave material, sheave diameter and cross-sectional 
shape, rope construction, rope core choice, etc).  The tower 
manufacturer's engineering team should have evaluated these trade-offs 
in selecting the type of wire rope used in a specific tower.  Why second 
guess?

   Guy cable does not need to bend and straighten as it passes around 
the sheaves of pulleys.

   W3YY reported he has used aircraft cable for guy wires.  Sure, it's 
possible.  But that's not what aircraft cable was designed for.  One can 
use needlenose pliers to punch a hole in the top of a paint can, too... 
or a screwdriver to chisel out some wood.  But aircraft cable IS more 
stretchy than 7-strand wire rope under load.  That extra stretch may not 
be a problem at one installation, but could be a problem at another.

   K7LXC's prime directive applies.

on 07 Mar 14 09:44 K7LXC at aol.com said the following:
>  
> In a message dated 3/14/2007 4:36:06 A.M. Pacific Daylight Time,  
> towertalk-request at contesting.com writes:
>
>   
>>  My understanding is that EHS is "galvanized steel cable",  which is not the
>>     
> same as wire rope. 
>  
>     Rope is "a strong, thick line or cord, commonly  one composed of twisted 
> or braided strands of hemp, flax, or the like, or of  wire or other material". 
> And technically, it's only cordage above one inch in  circumference and below 
> 10 (bigger-around than that is a cable). 
>  
>     Wire rope is a generic term used to describe just  what it is. In amateur 
> circles we tend to use several different terms for the  same thing; e.g. guy 
> wires, guy cables, etc. 
>  
>   
>>  While they might have the same breaking strength,  other
>>     
> characteristics may be quite different, such as abrasion  resistance.
>
>
>     Umm, I'm not sure about the abrasion resistance  but each wire rope is 
> characterized by the material, its lay (either right or  left), the number of 
> strands and the number of strand bundles that make up the  completed wire rope; 
> most crank-ups use 7x19 wire rope because all of the  small strands make it 
> easily bendable and flexible so it can pass  over pulleys many times without any 
> damage.
>
>   
>>  Rohn specs call  for EHS, not wire rope. I wouldn't fool around with 
>>     
> anything
> other than  what the spec calls for.
>
>
> Yep - the LXC Prime Directive still applies: DO  what the manufacturer says. 
>  
>     BTW there are 7-8 different grades of wire rope  for a given size; e.g. 
> 1/4" - galvanized, utility grade, stainless steel, EHS,  etc. - and it's really 
> important to use the right grips with the right wire  rope. They are NOT 
> interchangeable. 
>
> Cheers,
> Steve    K7LXC
> TOWER TECH 
>
>