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

[Chris Pedder]

At 15:51 13/04/2000 +0000, Ed, K4SB wrote:

>Guys, you should NEVER guy a crankup! If the tower can't stand
>what's on it, ( and I'm as guilty as all ) then put up another
>tower or do without.
>
>73
>Ed

Hi,

I am sorry but I must beg to differ with this rather sweeping statement.

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 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.

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.)

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

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!

Enjoy,

Chris G3VBL

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