[TowerTalk] Tower Guy Calculations

[Ken K6MR]

Back when guyed crankups were  all the rage, there were special stops made that were put under each extended section as the tower was raised.  This could be done at the 20 foot level.  Once the tower was fully extended, the cable was allowed to go slack and the tower sections rested on the stops.  This is part of the reason that guyed crankups extended one section at a time rather than all at once like a self supporting model.  The stops allow guying at every level.



The other system Jim noted was a lever and a stop welded on one corner at the top of each section.  The lever was spring loaded and would snap into place as each section was raised and provided the down stop.  A rope was attached to the lever so that when you lowered the tower you would pull the rope which would disengage the stop, allowing the section to be lowered.  These were, as they say, an “extra cost option”.  TriEx was the primary supplier of guyed crankups back in the day.  Even galvanizing was an extra option.  The standard models were painted only.  Probably why so few still exist.



Ken K6MR



________________________________
From: TowerTalk <towertalk-bounces at contesting.com> on behalf of jimlux <jimlux at earthlink.net>
Sent: Tuesday, October 15, 2019 5:25:38 PM
To: towertalk at contesting.com <towertalk at contesting.com>
Subject: Re: [TowerTalk] Tower Guy Calculations

On 10/15/19 11:13 AM, n6sj at earthlink.net wrote:
> Tom,
>
> Self-supporting crank-up towers should never be guyed.  When the wind blows,
> the lateral force is translated downward through the guy wires.  This adds a
> new load to the supporting cable that it was never designed for.  Typically
> the cable will break first, although sometimes one of the tower legs will
> buckle first, as it is being stressed by the additional downward force
> beyond its design as well.  The weak anchors for the guy wires are totally
> beside the point.
>
> Never guy a self-supporting crank-up!
>
> 73,
> Steve

You can guy the bottom section of a crankup without causing load issues
on the hoist cable - this might be a useful expedient for a tower
trailer type situation.

There are crankups that have funky locking mechanisms too, which might
be guyable at higher points (these are the 100 ft plus big trailer mount
units)- but they've clearly been designed for this
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