The pulley at the top of a gin pole merely changes
the direction of the rope. Please explain how a
block and tackle "Magically" reduces the force on
the rope to the top pulley and how to install the
block and tackle to achieve this magical reduction.
One more point. One pulley can give a 2:1 mechanical
advantage if one end of the rope is attached to a FIXED
support. If both ends of the rope are moving, there is
NO mechanical advantage, only a direction change
plus loss due to friction.
de Tom N4KG
On 13 Jun 2001 Mike Gilmer - N2MG <n2mg@contesting.com> writes:
> Steve, you are "half" right.
>
> The lift effort is part of the overall load on the
> ginpole (everyone forgets this), so without any
> mechanical advantage there is 2X load weight applied
> to the ginpole. If you employ a 3:1 advantage, and
> thereby reduce the lift force needed, you decrease the
> overall force on the ginpole.
>
> 73 Mike N2MG
>
> On Wed, 13 June 2001, K7LXC@aol.com wrote:
>
> > In a message dated 6/12/01 11:45:50 PM Pacific Daylight Time,
> > w7ni@easystreet.com writes:
> >
> > > A 3:1 mechanical advantage block and tackle system does,
> indeed, relieve
> > > about 1/3 of the load on the gin pole, in addition to reducing
> the number
> > of
> > > bodies required on the pull rope.
> >
> > 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
> > Tower Tech
>
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