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

[Stan or Patricia Griffiths]

K6ASL had a crankup tower failure in about 1964.  It folded over at the top of
the first section and was a 4 section, 72 foot crankup.  The antenna on top was
LARGE . . . 5 elements of a 60 foot boom on 20meters.  The cause of the failure
was cut guy wires by an irrate neighbor . . .

Another friend of mine had an interesting crankup failure.  It was a 72 foot
model also, but it had a stack of Telrex monobanders on it.  The tower was
normally kept fully nested to appease neighbors.  It was motorized but the
tower was not visible from the basement shack so it was often raised without
being watched.  It was probably raised at least a couple of times a day.

Because the time to raise it was several minutes and the owner was impatient,
he replaced the winch motor with one twice the normal size.  This improved the
raising speed by cutting the  time in half.  Over a period of months, the steel
cables chaffed away at the sides of the aluminum pullys and eventually one of
the cables slipped off the side of a pully and jammed around the pully axle.
Normally, this would stall the motor and blow a breaker, however, with twice
the normal sized motor, it did not stall.  Instead, it continued to crank until
it snapped a cable and the entire tower telescoped down from approximately half
way up.  Several elements were bent as the tower and beams came to a sudden
stop at the bottom.  Nobody was hurt.  The tower and beams were totaled.

Stan  w7ni@teleport.com

K2we@aol.com wrote:

> I'm curious. I'd like to hear from other users of Crank-up towers. Have you
> or someone you know had a Crank-up tower come down?? If so:
>
> 1. What caused it?? Broken Cable, High winds?? Defect in tower?? Etc.
>
> 2. Age & Type of tower?
>
> 3. What kind of antenna was installed on top??
>
> 4. Who installed it?? You?? A Professional installer??
>
> The reason for this survey is a friend was turned down by his town for the
> installation of a 52' motorized Crank-up on the grounds that if the tower
> falls over it will land in the street!!. I had mentioned t him that I've
> never heard of a Crank-up tower falling over from the base. Most failures
> happen when a cable snaps causing the tower to collapse inside it self but
> his town doesn't want to hear it.
>
> I'd like to hear from anyone out there who has had this kind of Crank-up
> tower failure.
>
> Thanks in advance.
>
> 73  Steve/K2WE
>
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