sorry not 10% (#440) !! example 1/4 at 60F is #670 tension
Guy Guy Cable Initial Tension (lb) Cable Ambient Temperature Diameter 0°
F 20° F 40° F 60° F 80° F 100° F 120° F 3/16 590 520 460 400 340 280 220
1/4 980 870 770 670 560 460 360 5/16 1650 1470 1300 1120 950 780 610 73
Bill N1HWC
On Wed, Jul 30, 2008 at 11:17 PM, Roger (K8RI) <K8RI-on-TowerTalk@tm.net>wrote:
> Dan Hearn wrote:
> > Dennis: You will find different opinions here on many subjects however I
> > believe there is almost uniform opinion on guying crankup towers. Don't
> do
> > it. That puts additional stress on the lifting cables when horizontal
> force
> > is applied to the tower. 73. Dan, N5AR
> >
> >
> (If I did the math correctly)
> Think of it this way. Each 1/4" guy wire at 440# tension (10% of 4400#
> strength) and 60 degrees at the anchor = 30 degrees angle at the
> tower. Neglecting the weight of the guy = 440*Cos(30) = 381#. There are
> three guys per level so that would be 1143# vertical load added to the
> tower and on the raising cables.
> Say a second set at 45 degrees = 440#*Cos(45)= 311# or 933# vertical
> load added, so adding just two sets of 1/4" guys properly tensioned will
> add 2076# vertical load to the tower and cables. IOW adding guys to just
> two levels that move adds over a ton of load on the cables. Using steel
> guys would also add additional weight from the cables as would larger,
> stronger guys.
>
> The strength of wire rope varies over a very wide range which makes the
> selection of the cables a primary consideration and pretty much
> eliminates what you find at the corner hardware, or big box store
> although the hardware store could likely order it to spec. This is also
> why it's important not to oversize the guys on a tower.
>
> 73
>
> Roger (K8RI - ARRL Life Member)
> www.rogerhalstead.com
> N833R (World's oldest Debonair)
>
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