WHAT I FREQUENTLY DO IS USE THE GIN POLE NORMALLY AND THE WHEN THE ROPE GETS
DOWN TO GROUND LEVEL USE A SNATCH BLOCK SO A HORIZONTAL PULL IS NOW WHAT IS
NEEDED....THEN
A SEPARATE BLOCK AND TACKLE ARRANGEMENT ANCHORED TO A TREE OR PICKUP TRUCK
OR OTHER IMMOVABLE OBJECT ACTS AS ONE END (THE STATIC END OF THE BLOCK AND
TACKLE....AND THE OTHER END - THE BLOCK THAT WILL BE MOVING IS ATTACHED TO
THAT HORIZONTAL ROPE COMING DOWN FROM THE GIN POLE AND OUT THROUGH THE
SNATCH BLOCK...
WHAT HAPPENS IS THAT THE LOAD IS DIVIDED OVER THE NUMBER OF TRIPS TO EACH
AND FROM THE TWO PULLEYS IN THE BLOCK AND TACKLE ARRANGEMENT...
SO HOW DOES THIS WORK - WELL YOU HAVE TO PULL A LOT MORE ROPE TO GET THE
SAME NET AMOUNT OF MOVEMENT - THE SAME RELATIONSHIP EXISTS (INVERSELY) TO
THE LENGTH OF ROPE PULLED AND AMOUNT OF ULTIMATE TRAVELED BY THE LOAD....
EXAMPLE THE LOAD YOU ARE MOVING IS A SECTION OF 55g AT ABOUT 100 LBS
IF YOU HAVE TWO ROPES BETWEEN THE BLOCK AND THE TACKLE PULLEYS YOU WILL PULL
LIKE IT IS A 50 POUND LOAD BUT YOU WILL HAVE TO PULL THAT FIFTY POUNDS TICE
AS FAR - IF YOU LIFT THE TOWER SECTION ONE HUNDRED FEET YOU WILL PULL TWO
HUNDRED FEET OF ROPE THROUGH THE BLOCK AND TACKLE....
SAME LOAD BUT WITH 4X ROPES IN THE B&T....FEELS LIKE A 25 POUND LOAD BUT NOW
YOU HAVE TO PULL 400 FT OF LINE THROUGH THE BLOCK AND TACKLE TO MOVE THE
LOAD 100 FEET....
IT IS SIMILAR TO THE VOLTAGE CURRENT RELATIONSHIP IN ELECTRICAL POWER
(COINCIDENCE, I THINK NOT) - YOU RUN THE 100 WATT APPLIANCE AT 100V AT 1 AMP
OR 50V AT 2 AMPS OR 25 V AT 4 AMPS...
NOTE THIS IS A LOT EASY TO PULL THIS WAY BUT TAKES COPIOUS AMOUNTS OF ROPE
TO DO - WE FREQUENTLY WILL RE-SET THE BLOCK AND TACKLE SEVERAL TIMES TO
AVOID HAVING IT AT THE OPPOSITE END OF THE PROPERTY FROM WHERE THE LOAD GOES
VERTICAL! PULL IT UP A THIRD OF THE WAY....RESET (OPEN UP THE BLOCK AND
TACKLE SO THE TWO ARE FAR APART AGAIN...AND NOW ATTACH IT TO A LOOP TIED
INTO THE LOAD ROPE AS IT EXITS THE SNATCH BLOCK
SORRY FOR THE CAPS....TOO LAZY TO RETYPE IT...
K4OJ
----- Original Message -----
From: "Chris BONDE" <ve7hcb@rac.ca>
To: "jljarvis" <jljarvis@adelphia.net>
Cc: <towertalk@contesting.com>
Sent: Thursday, July 11, 2002 6:20 PM
Subject: Re: [Towertalk] mast disaster avoidance
> It has been awhile since I have done any mechanical stuff with pulleys. I
> think that you are on the right road but not all the way.
>
> If you are lifting a 100lb weight with one pulley at the top, you need
100+
> lbs on the other side to lift it. I would then say that there is 200+lbs
> of weight on the pulley.
>
> If you are lifting a 100lb weight with 2 pulleys at the top and one on the
> load, then you have a mechanical advantage and need only 1/3 of 100+ lbs
to
> lift the weight (I think that that is correct, but it is a lot
> less) Therefore, the total weight on the pulley is 100lbs plus the
reduced
> amount hence less.
>
> I think that this is correct.
>
> Chris opr VE7HCB
>
> At 02:00 PM 2002-07-11 -0400, jljarvis wrote:
>
> >Mike...
> >
> >If you had a ginpole with a 2 wheel block on top (never seen
> >one, myself. Do they exist?), you would reduce the load on each
> >run of line, proportional to the number of lines.
> >
> >But the load on the axle is still the sum of the line-loads.
> >i.e., unchanged.
> >
> >The compressive load on the ginpole itself is thus still the
> >same, and the out-of-column bending loads are the same.
> >
> >
> >Jim/N2EA
> >
> >
> >-0-
> >From: "Mike Gilmer"<n2mg@eham.net>
To: <towertalk@contesting.com>
> >Date: Thu, 11 Jul 2002 12:16:03 -0300
> >Subject: [Towertalk] Re: mast disaster avoidance
> >
> >I agree with most of N2EA's post except:
> >
> > > Solutions using added pulleys still leave the same load on
> > > the ginpole material itself
> >
> >This is not true. As has been oft-discussed on this reflector in the
> >past (and still misunderstood), judicious use of "added pulleys" can
> >reduce the total load on the ginpole.
> >
> >Mike N2MG
> >
> >
> >
> >
> >_______________________________________________
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>
> _______________________________________________
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additional 5 percent off
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