Hi Gary,
Well, I hate to say this, but I don't fully agree with your analysis of the
system you
diagramed. I do agree that the down pull tension will only have to be 100#,
but it
won't reduce the load on the gin pole since you have TWO strands of rope on the
down
pull side with 100# tension in each one, both pulling down. This means the
single
rope above them will have the original 200# tension in it and therefore, the
gin pole
still sees 400#.
Stan w7ni@teleport.com
Gary McDuffie, Sr. wrote:
> On Fri, 02 Apr 1999 23:18:04 -0800, Kurt Andress wrote:
>
> > I can't see anyway that adding a mechanical advantage to the load side or
> > lift
> > side of the system will result in a reduction in the load applied to the
> > top of
> > the gin pole.
>
> You don't add it to either side of the gin pole. You replace the single
> pulley at the top of the pole with a block and tackle.
>
> > It can make the job easier for the fellows pulling on the rope, but the gin
> > pole
> > doesn't get to enjoy the benefit. Gotta have a net load of 200# on each
> > side, no
> > matter how you achieve it! The load at the top of the gin pole is
> > determined by
> > the line tensions exiting either side of the sheave and their angles.
>
> That's what I originally said also. But, if you revert back to my last
> description and replace the single pulley with a 2:1 advantage B&T, you
> only have to hang 100 lbs on the pull side to equalize the 200 lbs load.
> You now only have 300 lbs on the pole (instead of 400 lbs).
>
> Gary
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>
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