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Pulley Question.

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Pulley Question.

Unread postAuthor: boyntonstu » Fri Aug 14, 2009 1:46 pm

What would be a low friction design to pull a string with a 200 pound tension 120* around an axle/pivot?

A small diameter light weight pulley mounted on a ball bearing comes to mind.

I have some old roller skate wheels in my junk pile and they spin easily.

However their mass is quite large and therefore the moment of inertia would be a drag.


My idea is to vertically pull rubber bands and transfer the force to horizontal.

BoyntonStu
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Unread postAuthor: AngryChauncey » Fri Aug 14, 2009 2:04 pm

I forget the formula to find the MA (mechanical advantage) when using pulleys, but what you want relies on this principle. The low friction that you want will come with using enough pulleys. Google "pulley mechanical advantage" and you should find what you need.
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Unread postAuthor: jrrdw » Fri Aug 14, 2009 2:04 pm

Try a bell crank. The longer the arms the more leverage etc...
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