[TowerTalk] Have you had a crank-up come down?

[Stan or Patricia Griffiths]

Chris Pedder wrote:

> I am aware from postings on this reflector that there are considerable
> differences of perception concerning crankup towers on the two sides of the
> Atlantic. I would guess that the majority of amateurs, who have towers,
> here in the United Kingdom have crankups.
>

There are lots of people over here who are pro-crankup as well.  I, personally,
am probably the most outspoken anti-crankup person I know.

>
> There is a number of reasons for this, not least of which is the difficulty
> in obtaining planning permission (building permit) for any sort of tower.
> In most areas the ability to retract the tower 'when not in use' is a
> considerable plus with the planning authorities.
>

Boy, we have the same sort of problems getting permission to put up towers and,
especially in California, it seems, crankups are very popular and for the very
same "planning authorities" reasons.

>From the practical viewpoint, how many crankups are ACTUALLY retracted when not
in use?  I rarely see a retracted crankup.  The idea looks good on paper to
planning authorities but is rarely put into practice once the tower is
installed.

>
> First of all some crankup towers are designed to be guyed. I should say,
> however, that the tensions used are probably rather less than those used on
> a fixed tower. I do not happen to guy my crankup even though it carries a
> substantial headload. The usual failure mode, in extreme weather
> conditions, is bending of the middle section followed by collapse of the
> entire system. This can be prevented by suitably placed, lightly tensioned,
> guys. (As the wind increases the common 'gravity' system used here will not
> bring the tower down due to binding/locking of the sections. A positive
> pull-down would solve this but is seldom used in U.K. and people do not
> learn to get them down early enough or to guy them loosely.)

One of my points, exactly.  People are quite well aware of what they SHOULD do
regarding crankup towers, but very often simply DON'T do it . . .

>
> Before anyone tells me that any guying system increases the tension in the
> lifting cables I should point out three things:
>
> 1.  We use a lock system which takes the tension off the cables.
> 2.  I did say that tensions are lower than on fixed towers
> 3.  The cables will take it anyway.
>
> There is, on this reflector, a very evident 'anti' sentiment with regard to
> crankup towers and this is a pity.

I can identify with this statement since I am the outspoken "anti" person and
the only real "pity" is because of all the tragic accidents that occur because
of crankups.

> Each type, fixed or crankup has its uses
> and each is capable of being used safely over a long period of time.
>

Here, I beg to differ.  If you could obtain statistics, you would probably find
that failures and injuries occur MUCH more often on crankups than on fixed
guyed towers.  Of course we can't obtain those statistics since most people
are  embarassed to discuss their tower failures since most of them are related
to their own personal errors or stupidity.

>
> I will admit that I had a tower 'come down' on me but that was due to
> criminal neglect on my part, having had a new set of lifting ropes in the
> garage for eight years and failing to fit them!
>

Well, you are one who is not too embarassed to admit it.  Thanks for that.  An
interesting possible way to evaluate "safe use over a long period" would be to
calculate the number of "tower-years" a person has had experience with and
compare that with the number of failures or injuries.  Here is my personal
experience:  I have had as many as 4 towers up at one time and for decades.
These are all guyed, fixed towers.  So far, my total "tower years" is 120 with
NO failures.

I wonder how that compares with others . . .  If you have had one crankup for
20 years and it failed just once, I would regard that as a dismal record . . .

Personally, I think "planning authorities" are often among the most
ill-informed and dim people I have ever met.  They should be putting personal
safety way ahead of aesthetics and crankups should be outlawed entirely as a
dangerous hazard.  I think the statistics we can't get would show this very
clearly . . .

Stan  w7ni@teleport.com

>
> Enjoy,
>
> Chris G3VBL




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