Author Topic: Knot or not?  (Read 6022 times)

struktor

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Knot or not?
« on: July 20, 2011, 10:24:31 PM »
Compare:

1/
Ashley's Book of Knots (ABOK)  3234 Double Spanish burton.  
Power gained- five times.   :)

2/
A Double Spanish Burton fig. 102. Power gained- four times            :(
http://www.gutenberg.org/dirs/3/0/9/8/30983/30983-h/30983-h.htm#P54
or
http://www.gutenberg.org/files/30983/30983-h/30983-h.htm#P54

                                    Title: Knots, Bends, Splices     
                                           With tables of strengths of ropes, etc. and wire rigging
                                    Author: J. Netherclift Jutsum
                                    http://www.gutenberg.org/files/30983/30983-h/30983-h.htm

Compare:

1/  
Double Spanish Burton p.13. Power gained- five times:
http://mytreelessons.com/ks/mz/lines_of_force.swf            

2/
Ashley's Book of Knots (ABOK)  3235 Double Spanish burton.     ???
Power gained- five times.


Struktor
« Last Edit: July 21, 2011, 08:00:42 AM by struktor »

TheTreeSpyder

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Re: Knot or not?
« Reply #1 on: July 21, 2011, 01:09:25 AM »
The Numbers look right to me; must understand legs of pull, and count how many pull on the load.

http://mytreelessons.com/ks/pulleys.png

This is assuming single pull, but can '2 hand' to place your body weight + your effort + the equal and opposite of your effort ( at a lessor input point of 2 less pulls as multiplier).  This can make a 3x system have a potential of 3x bodyweight + 4x Effort.  But, can make a standard 5x have a potential of 5x bodyweight + 8x Effort.

http://www.smackdock.co.uk/tackles.htm

http://www.mytreelessons.com/Marlinspike_%20Sailor.htm

http://www.mytreelessons.com/Marlinspike_%20Sailor_Rig.htm

http://www.mytreelessons.com/Flash/2handing.swf
« Last Edit: July 21, 2011, 03:18:16 AM by TheTreeSpyder »

struktor

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Re: Knot or not?
« Reply #2 on: July 21, 2011, 07:25:32 AM »
http://mytreelessons.com/ks/pulleys.png
''i do think this line should go to center of pulley and end, not side''

I think so too.
Thank you

ABOK #3275
From Furttenbach (1629) :
http://digital.bibliothek.uni-halle.de/hd/content/pageview/117157
« Last Edit: July 21, 2011, 12:40:35 PM by struktor »