On 17 Aug 1998 rick@area.com wrote:
>
> There was some recent discussion on towertalk about using cranes to
> install towers. I am confused by what I read. On the one hand,
> various people mentioned that you can't just assemble 90 feet of
> Rohn 25 on the ground and casually lift it up into place because
> it will bend in the middle, etc. On the other hand, I seem to remember
Having put up several of my own towers with a crane, my comment is if a
90' tower is flimsy enough that you can't pick it up at the 2/3 point with
a crane, then I wouldn't want to use it at all.
The skinniest I've put up has been 110' of a 16" face (solid rod
construction) tower, and it survived fine. The largest has been 160' of
40" face, which all went up in one peice. A dozen in between, of various
sizes. The crane was the limiting factor (reach wise) as it has max
height of 96' with a working height of around 90'. Weight isn't usually
the issue. I also put up a large 120' microwave freestanding tower, but
for that weight was an issue so that had to picked up without the jib
attached. The crane was a Grove 18 ton hydraulic truck unit.
> > Would it be practical to build a new tower from scratch be >
> assembling the top few sections on the ground and then lifting > that
> assembly up and inserting additional sections underneath. > How do you
> determine how many sections can be assembled on the > ground? How high
> of a tower can be built this way (apparently > at least 80 ft)? How
> much crane time is needed?
I think it's very practical, but I'd put most of it up (all if possible)
in one peice. Lighter towers wouldn't even need a "real" crane, a lighter
and easier to get into small spaces unit generally called a "picker" truck
can do the job. Some of these have very significant mast/hoists, capable
of reaches well over 120', and can handle a reasonable tower with ease.
For even smaller jobs, sign repair trucks might be acceptable, but most of
what I've seen have been pretty lightweight units.
Time wise, EVERYTHING takes longer when the meter is running! Be organized
and plan everything through.
73 Don
VE6JY
VE6JY Don Moman email: ve6jy@freenet.edmonton.ab.ca
Box 127 Lamont, Alberta email forwarding: ve6jy@rac.ca
T0B 2R0 (403) 895-2925
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