Dan Levin wrote:
>My idea is to take 6 pieces of 1/4"x2"x2" or so angle
>iron, and drill a 1/2" hole about 2" from one end. I
>would bolt these pieces horizontally onto 2 legs of
>the tower about every 10 feet, with the end with the
>hole sticking out from the tower 6" or so and with
>the hole facing up and down. Then I would attach one
>end of an 80 foot long piece of 1/4" wire rope to the
>top of the tower, and thread it down through the
>holes in the pieces of angle iron and then attach it
>to the bottom of the tower. So I would have a wire
>rope running up the tower, spaced off the tower 6" by
>these pieces of angle iron every 10 feet.
>
>The idea is that I would clip my fall arrest lanyard
>to the wire rope as I climb up or down. Every 10
>feet, I would come to one of the pieces of angle
>iron, and I would have to unclip from the wire rope
>on one side of the iron and re-clip to the wire rope
>on the other side. Other than that, while I am
>climbing the lanyard clasp would just slide on the
>wire rope.
>
>If I fall, the lanyard clasp would slide down the
>wire rope until it got to the nearest piece of angle
>iron where it would stop. The angle iron would catch
>the lanyard, and the lanyard would arrest my fall.
>In essence, I would be clipped in to the next lowest
>angle iron. My fall would never be more than 10 feet
>plus the length of my lanyard.
Exactly how would you clip your lanyard onto 1/4"
wire rope? There are basically two types of commonly
available rope "grabs" (or sliders):
1) made for 3/8" wire rope, and
2) made for 5/8" synthetic rope.
Also, although rope grabs are fairly easy to remove
and re-affix to the line, you do not want to have to
do that every 10' or 20'. Of course, you could have
one for each span, but they cost $150 each or so.
Commercial fall arrest systems use snap-in standoffs.
The first guy up the tower pulls the safety line out
of the standoffs, and it generally is left that way
until that crews' job is done. The last guy off the
tower pops it back in on the way down.
The standoffs are generally located every 20' or so.
They are sold as parts of a system (not cheap of course),
but the standoffs themselves, if you can find them
separately, should be fairly inexpensive. Virtually
all tower manufacturers offer vertical safety line
kits as accessories.
Alternately, you could homebrew some sort of snap-in
bracket. It's only purpose is to keep the cable from
slapping the tower - but it should not impede the
climber. If dealing with your fall arrest system wears
you out by the time you reach the top, assume it needs
improvement.
The type of standoff that comes with some crankups for
holding the feedlines would probably work with a little
modification.
73,
--
Steve K8LX
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