in an old post,
I calculated the forces when raising a crankup with a ginpole at various
(there are three links there, one is an excel spreadsheet, others show what
shorter ginpoles (like a raising fixture which is what, around 8' maybe)
the forces on everything a lot. I used a 14' ginpole as a result for my
(I didn't have a raising fixture).
I calculated assuming a direct connection to the tower (no compound
on most raising fixtures). But you can divide by 2 in the right places
to get the effect
of a 2:1 compound pulley setup.
adding weight to the top of the tower, when lifting, obviously causes a
than linearly distributing added weight across the tower. ...i.e. 300
lbs at the end
of the tower, is worse than a 300lb heavier tower. Because the tower is
a class 3 lever, and the pull effort is closer to the fulcrum than the
load is, so the 300 lbs
My calcs break the analysis in two. The weight past the tower attach
point is a class 3 lever.
The weight below the tower attach is a class 2 lever. I assumed the
attach point height
equals the ginpole height always. I assume the tower weight is linearly
simplify the analysis with an appropriate point load at the halfway
there are two, because of the two different class 3 and class 2 lever
You can modify/do the calcs, but it's not out of the question to exceed
a 1500 lb
pulling force with a 2:1 compound pulley, with my example. (which had
on top of the tower). I would do the calcs with the antenna load at
even though you would install them at a slight angle. The difference can
I don't know the exact height of the raising fixture in question, or the
height of the attach point to the tower, though.
Food for thought: if you think you need stronger winch, at a certain
point you need
stronger cable (like 1/4"). I'm not sure what size cable was on your
1500 lb winch.
The rest of the setup may be strong enough already.
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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