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Mechanical advantage
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oldtimer
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PostPosted: Sun Jul 12, 2009 3:30 pm    Post subject: Mechanical advantage Reply with quote

This subject is one of life's great mysteries which has been with me all my days.I doubt if my few remaining brain cells will be likely to bring a grasp of this situation when years when I could reasonably hope for a bit more grey matter to focus on this other matter,if you get my drift,failed.
While not yet in Shakespeare's Seventh Age of Man I am a candidate for number 6.
It is not that I DOUBT this concept works.I seem to recall seeing a T.V.
programme where a sizeable number of people wrapped rope back and forth between pulleys and then proceeded to pull a CENTURION TANK!
It seems to me to be the sort of shenanigans that would have merited
being burnt at the stake at one time,even in the absence of the tank
Perhaps there will be a rapid demand that I be banished from this erudite
gathering but I will just have to hope that you have some concealed shortcoming ,or even the same one!
oldtimer
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47Jag



Joined: 26 Jun 2008
Posts: 1480
Location: Bothwell, Scotland

PostPosted: Sun Jul 12, 2009 11:37 pm    Post subject: Reply with quote

Oldtimer,

Comparativly ancient man had mastered this concept to hoist sails and move rigging spars on ships. I don't know how far back but at least 500 years.

Art
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peter scott



Joined: 18 Dec 2007
Posts: 7211
Location: Edinburgh

PostPosted: Mon Jul 13, 2009 12:08 am    Post subject: Reply with quote

Think of it just like gearing. You reduce the force by increasing the required movement. For a simple two rope system you need to pull the rope twice as far in order to move the object. Counting the number of ropes between the pulley blocks tells you the advantage ratio.

2 ropes = twice the force
3 ropes = thrice the force

etc, etc. (approximately, because friction in the pulleys may act against you slightly)

Peter
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1939 SS Jaguar 2 1/2 litre saloon
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oldtimer
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PostPosted: Mon Jul 13, 2009 11:19 am    Post subject: mechanical advantage Reply with quote

Thank you both,Art and Peter,for your input.
The point Art made is,perhaps,akin to my position.I know the system works but could never have explained it,or why it does.
I suspect many of these chaps accepted it because the forebears had done it that way and it worked and they didn't know of any other way.
The "If it ain't broke dont fix it" approach.Maybe they would not have been too good at explaining the theory to some dimwit like me!
As for Peter,I would, almost, have put money on his being ready,once more,to attempt to help me as he has in the past.
I can say that he invariably explains things in clear,simple terms and that the concept of considering the system as a series of levers has helped
immensely.
Once again my thanks to you both.Hope all is well Jaguar wise
Regards
John
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clan chieftain



Joined: 05 Apr 2008
Posts: 2041
Location: Motherwell

PostPosted: Mon Jul 13, 2009 10:10 pm    Post subject: Reply with quote

Being a bit of an oldtimer myself now...62 past but wasnt that how they built the pyramids and stonehenge and the like. Cool
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The Clan Chieftain
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peter scott



Joined: 18 Dec 2007
Posts: 7211
Location: Edinburgh

PostPosted: Mon Jul 13, 2009 11:17 pm    Post subject: Re: mechanical advantage Reply with quote

oldtimer wrote:
Hope all is well Jaguar wise
Regards
John


Hi John,

Yes thanks, she's back on the road but it's a bit of a long story which isn't quite finished yet but I'll (hopefully) tag an ending on the long saga soon.

Regards,

Peter
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1939 SS Jaguar 2 1/2 litre saloon
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