In a message dated 6/13/01 8:20:39 AM Central Daylight Time, K7LXC@aol.com
writes:
<< You sure? Isn't a hundred-pound load going to weigh 100 pounds no
matter
how the block and tackle are set up? The load effort on the end of the rope
will be reduced but the dead weight of the load stays the same. You still
need a suitable ginpole.
Cheers, Steve K7LXC >>
Good grief! Steve, as usual, is correct. It matters not whether you have a
4:1 or 8:1 block and tackle set up for lifting--the load on the gin-pole is
the same (actually plus the weight of all that rope).
I do the opposite when lifting Rohn 55 sections. I go for mechanical
DISADVANTAGE, and speed ADVANTAGE. I use a CJ5 to pull with a movable pulley
attached to the monster hook on the front of the Jeep. This requires the
Jeep to back away from the tower only half the distance of the lift and
surely the Jeep doesn't flinch at 250# of pull compared to the normal 125#.
Went to this because I only had 60' of clear backing room and needed to lift
110'. With good sailboat type pulleys (a turning one at the bottom of the
tower and the movable one on the Jeep) and strong rope there is no problem.
The load on the gin-pole is still the same but the one spot with double load
is the movable pulley on the Jeep.
John, N0IJ
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