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@contesting.com> on behalf of jimlux
<jimlux@earthlink.net>
Sent: Tuesday, October 15, 2019 5:25:38 PM
To: towertalk@contesting.com <towertalk@contesting.com>
Subject: Re: [TowerTalk] Tower Guy Calculations
On 10/15/19 11:13 AM, n6sj@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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