![]() Ovbiously the tension in each line will have halved as they share the load. Then half the rope and join the ends, then tie the rope to something fixed using a threaded fugure of eight in both the lines. With refernce to your tug of war argument the situation would be anagulous to puting the same force as applied by both people tugging the rope on to one end of the rope with the other end tied to something fixed using a threaded figure of eight. Admitedly if you replace the top point with a hex I'm not too sure if the hex or the krab would be the weak point but I'm fairly sure it would be the hex, it makes little difference to my argument either way. Obviouly attaching the weight by a crab at the bottom will now make either the top or the bottom of the system the weakest point. It should be clear that the tension in both ropes will be the same (24.5 N) but now the weak point is where the rope goes through the crap at the top of the system. Now instead of tieing it to the ceiling using a fugure of 8 on both lines, clip a crab up there and slip the top loop of rope in to it. Now join the ends of the ropes together and treat the new rope as a single line and do the same thing, obviously the tension in each line will have halved (24.5 N) as they are sharing the load. If you suspend a 5 kg weight from a piece of rope tied to the ceiling with a threaded figure of 8 the tension in the rope will be 5 * g = 5 * 9.8 ms-2 = 49 N. Spectra has been know to de-sheath during tests. I think it's something to do with the kevlar being brittle in the spectra and also that it is more slippy. However some of the reports I've read suggest that 8mm rope or nylon slings which are weaker than 5.5 spectra in field tests actually turn out to be more relieable. I've read a bit about this and I do a lot of math. The loop in the top takes the full force of the fall as where the ropes coming up through the hex meet the tension must be additive of the tensions on the ropes on either side.ĭunno if that made any sense. Now as the rope say will break at 15 KN, the max each side rope can take before the top loop breaks is 7.5 KN as the knot will not break/slip until around 12 KN this is not the weakest point of the system. The knot weakens the rope by about 70% if tied well. Many people think it'll be the knot but of course the knot only takes half the strain placed on the piece as it lies on one side of the ropes comming out of the hex, aS the force of the fall is halfed on each rope coming out from the hex. The weakest point on a hex will be the loop where the cord threads the top of the hex. Nylon coord really isn't all that strong until you get to 8mm. I would have thought spectra rope was best until you get to 8mm nylon rope as it's far stronger than nylon rope. What's the general concensous do people prefer spectra or nylon cord.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |