Fast Fours Mechanical Advantage System
The Fast Fours is a simple variation on a standard set-of-fours. The difference is that the far end of the rope is not terminated on the becket of a pulley. Instead it is run through another progress capture pulley. This means that an operator can either pull on both ends simultaneously to yield a fast take up 2:1 or a single strand for a 4:1.
There is another unique advantage of this system for fallen worker and confined space recovery. If capable, the fallen worker can pull on one end of the system while the rescuer pulls on the other which speeds the recovery, halves the individual work, and involves the victim in the task.
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About The Author
Richard Delaney
Richard Delaney has worked professionally with ropes since 1992 as a multi-pitch rock-climbing instructor, technical rescue instructor and rope access technician. Understanding and teaching the Physics of Rigging is a core passion of Richard’s, one based on his experience, and his prior professional life as a qualified engineer.
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Very clever.
Trying to figure out if I can rig the boom on my sail-boat like that!
I can’t remember where I saw this but I got the idea from a sailing pic. Fast take up of a main sheet during a jibe.
There are so many great ideas that sailors and others have used for hundreds of years – just takes us Rope Techs a while to catch on.
Something like this:
http://www.harken.com.au/content.aspx?id=3902