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:
>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.
>The compressive load on the ginpole itself is thus still the
>same, and the out-of-column bending loads are the same.
>From: "Mike Gilmer"<email@example.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.
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