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3 versus 4 guys

To: <>
Subject: 3 versus 4 guys
From: (
Date: Tue, 11 Jun 1996 14:17:31 -0400
In a message dated 96-06-11 11:40:24 EDT, you write:
>I would say that the quadrature guying is because of the space required for
>mounting booms on the tower top while on the ground.  I don't know what
>forces you are talking about as there would be no rotational twisting forces
>the tower (in the plane of the earth) while folding it over (assumes no
>I don't see that having quadrature vs triangular guying improves things at
>base of the tower while folding it over.  The hinge guys must resist the
>introduced by the folding action and 3 guys work as well as 4.

Hi, Bob --

      Actually I sent that post without checking my Rohn book.  The specs
call for 4 guys over the entire structure.   I was in error and apologize for
any confusion.

    IMO the reason that four guys is used is is because of the potential for
larger torsional stresses both in the lowering/raising mode and in the
upright position.  As you know, some beams are not symetrical in terms of
their mechanical balance.  If you have an unbalanced load such as this on
your foldover tower, there will be a torsional load on the mast exerting some
twist to the tower.  Also, even though the section at the hinge is pinned, it
is not connected 100% to the rest of the tower like a regular section is.  It
is also a weak link in the ability of the tower to absorb  these torsional
forces.  Therefore, having 4 sets of guys gives the tower additional twist
resistance to make up for the design compromises of the hinged tiltover
design.  Like I said, this is my opinion based on my observational experience
in working on towers.  BTW, I've rarely seen a tiltover section that wasn't
bent or broken at some time in its history.  Don't overestimate the
mechanical strength of any tiltover fixture.  73,  Steve   K7LXC


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