Date: Thu, 11 Apr 2019 11:33:30 -0700
From: Grant Saviers <grants2@pacbell.net>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Fwd:? Fwd: Tower foundation and bedrock
<In addition to Steve's cautions, I would add that crank ups depend on
<the hoist cable strength to stay elevated (unless a locking tower which
<is designed to be guyed when locked). Guys add a lot of downforce on
<the hoist cable, both from the preload, and then several times more at
<max wind velocity. So check out the design calcs for all cable loads
<against its rated break strength. Sheave and winch winding diameters
<also affect the break strength as do the sheave axles.
<All together, the PE calcs I have would strongly advise against adding
<guys to my HDX589. If the analysis shows the bottom section or anchor
<system is most likely to fail first, then I don't think there is much
<downside to adding guys to it, since the ground level wind field
<probably won't add a lot of tension to those guys.
<Grant KZ1W
## You can not guy a US TOWER product, period. The only exception per UST,
is guying the very bottom section. IE: guyed at the 21 ft level.
## Other brands of crank up towers include locking plates, that can be
deployed, with the
tower extended to any height..up to and including max height. The locking
plates are typ installed
at the 21 ft level. They take the stress completely off the drum cable.
Those types of towers
can be guyed on their upper sections.... but those types of towers also have
a cable for EACH face
on all the upper sections. Done that way, and sized correctly, so the lifting
cables can handle the huge pre-load
and also much more, at max wind velocity. Worse case scenario is when the
wind is blowing between 2 x guy wires.
The downward force on the tower is now DOUBLE what it would be vs wind
directly inline with a guy wire.
## Guyed crank up towers have come down in the past, its not something new.
Jim VE7RF
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