Cheese press with pulley system

[smilingcalico]

Quick inquiry, maybe.  I've been examining a few of the crafty presses out there on the site and have seen someone with a block and pulley system.  I'm unclear as to the need of the pulley, as it seems the downward force of whatever weight is being used would do the same work as without the pulley.  Can someone clarify its benefit for me?  Thanks.

[KosherBaker]

Hey SC. I think it was covered well in this thread, along with a few other press related topics. See what you think:
http://cheeseforum.org/forum/index.php/topic,4026.msg32048.html#msg32048

[DETERMINED]

Try to think of pulling a gate closed, if you pull on the rope and the gate has a dragging weight of say 30 lbs and you have to pull the rope 10 feet to get it closed this is the amount of work you are trying to do.  If you wrap the rope around the post that you are closing the gate against you will have created a pulley, but now you will have to pull the rope twice as far{20 feet} to get the gate closed the difference being is that you will now only have a dragging weight of 15 lbs {plus minimal friction} The pulley is not making you work less you are still moving 30 lbs 10 feet you are simply applying your energy in a way better suited to your ability. If  this makes  sense to you then think of a dutch press that you have 50 lbs hanging on the end of the arm . Now try to imagine a cable fixed to the base of the press straight down below the end of the arm,next a pulley attached to the end of the arm the cable going through the pulley and your 50lb weight hanging from the cable, you are now applying 100 lbs of force to the end of the arm,  The difference being the travel [working]distance is now half of what it was before.

[FarmerJd]

Depending on the position of the pulley, it can increase the force applied by the same factor as the number of pulleys. In other words 2 pulleys gives a mechanical advantage of 2 if they are positioned correctly. This is how a chain hoist works if you have ever seen one.

[smilingcalico]

Physics never was my strong suit.  I'll have to read these a few times to understand better, but thanks, I know you have all put me on the right track.