I agree completely with your analysis Guy. Which end of the
gin pole rope is attached to a "block" ? q.e.d.
Bottom Line: The mechanical advantage in a lossless system
equals the number of supporting segments between the LOAD
and the SUPPORT.
For a GIN POLE this number is ONE i.e. NO mechanical advantage.
Sum of Forces approach: Load on one side of the gin pole pulley
must be balanced by the "pull" on the opposite side. The Gin pole
supports the LOAD plus PULL, or twice the weight of the load.
Rope In = Rope Out approach: The amount of rope going into
the gin pole pulley equals the amount of rope coming out of the
gin pole pulley. Mechanical advantage = ONE.
The gin pole rope MAY be attached to the HOOK of a Block
and Tackle which will provide a mechanical advantage to the
puller but NOT to the gin pole. The other end of the block
and tackle is presumably anchored to the ground. Two ropes
are involved here. The block and tackle rope will travel X times
the distance of the load where X is the mechanical advantage.
The gin pole rope will travel the same distance as the load,
i.e., the height of the tower.
Time for a new thread.
de Tom N4KG
On Wed, 13 Jun 2001 "Guy Olinger, K2AV" <firstname.lastname@example.org> writes:
> The reduction mechanism of a ganged pulley system is in the number of
> feet of rope the worker pulls in as a ratio to the distance the load
> travels. In a two to one system the worker pulls 200 feet of rope to
> lift the object 100 feet, thus the analog to a lever, and the
> Two to one: rope tied at top block, through pulley at bottom block,
> through pulley at top block, to worker.
> Three to one: rope tied at bottom block, through pulley at top
> block, through pulley at bottom block, through pulley at top block,
> to worker.
> Four to one: rope tied at top block, through pulley at bottom block,
> through pulley at top block, through pulley at bottom block, through
> pulley at top block, to worker.
> > From: Mike Gilmer - N2MG <email@example.com>
> > Date: 2001/06/13 Wed AM 09:06:35 EDT
> > To: firstname.lastname@example.org
> > Subject: Re: [TowerTalk] Ginpole for 20 foot sections
> > Nothing "magical" about it...
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