On Wed, 5 Nov 1997 10:28:55 -0600 (CST) firstname.lastname@example.org writes:
>questions; how easy/difficult is it to un-tension and detach the top
>set of guys prior
>to folding over - can it be a single person job?
My Rohn 25 48' foldover has been up for 20 years. To remove the
top guys you just unscrew the turnbuckles until the top guys are
loose and unscrew a bolt, or in my case with old-style Philly
terminations, pull a cotter pin. It's a one person, 4 minute job.
When the tower is folded over, the two bottom guys closest to the
antenna also go slack and can be removed temporarily if they get
in the way.
> What type and how
>maintanance need to be done on the winch, cable, foldover section etc.
I've never done any maintenance on the cable or foldover section.
I had to disassemble the winch once and clean it up because the
clutches were stuck. It was no big deal. The winch has a little
manual with an exploded view of all the parts and how they fit
together. Actually, I fold it over so seldom, I really should
take the winch off and store it in the garage when it is not being
used. Keep in mind that I live in a very dry desert.
> Are there any
>reports of disasters/failures during the foldover process? How does
>the Rohn foldover
>concept compare with crank-ups?
I think it's safer than a crankup, but I would not overload
it. The current Rohn catalog specifies a safe dead weight load
at the apex. Old catalogs used to have an additional specification
"safe moment about the hinge." As I remember that spec, it was
approximately = (safe load at apex) x (distance from apex to hinge).
In this case 190 x 16 = 4750 ft-lbs. You apparently have a long
mast, so you need to go through the moment calculation for each
component; rotor, mast, each antenna, coaxes, etc. to make sure
you don't exceed 4750 ft-lbs.
The foldover is not as cost effective as it used to be when priced
against crankups. It's no fun installing the boom section, since
it weighs 165 pounds. It has guy wires, which are unsightly,
and always in the way when you're trying to do something. If I
were to do it again today, and had $2200 to spend, I think I'd
buy a heavy duty 55' crankup. Actually, I think I'd spend $4000
for an LM-470E 70-footer. Not many choices available when you
don't like high work. Oh by the way, installing or removing a
foldover requires high work.
Dave Hachadorian, K6LL
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