Hi Dave,
And thank you, too, for the excellent example of mechanical advantage using
pullys. The only difference between my system and yours is that I use a
double pully at the top and a single pully at the load and I get a
mechanical advantage of 3:1 instead of 2:1. The principles are exactly the
same.
Please help me convince these guys that there really is something to this.
I can tell you from personal experience that using a block and tackle with a
gin pole to lift a long heavy mast makes a HUGE difference in how easily and
safely it goes up.
Stan w7ni@teleport.com
k6ll@juno.com wrote:
> This is interesting discussion. Consider the following
> simple setup:
>
> Take a standard gin pole, run the rope through the pulley,
> but instead of attaching the rope directly to the load,
> run the rope through a second free pulley, which is attached to
> the load. Now run the end of the rope up to the top of the
> gin pole, and firmly secure it to the top of the gin pole mast
> somehow. Now attempt to lift a 100# mast.
>
> The 100# is supported by two ropes, so the tension on the rope
> is 50#. Tension on the rope is constant in a pulley system, so
> the people on the ground are exerting another 50#
> downward tension, and the resultant downward force on the gin
> pole is 150#, instead of 200#, which it would have been if the
> second pulley had not been used. Additionally, the people on
> the ground only have to exert half the force. It sounds like
> a pretty slick idea to me, and it only takes one additional
> $10 pulley, and a longer rope! The rope has to be longer by
> the height of the tower plus the length of the gin pole, but it
> needs to be only half as strong as the rope without the second
> pulley.
>
> Dave Hachadorian, K6LL
> Yuma, AZ
> K6LL@juno.com
>
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