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Mechanical Advantage is a Myth
🕑 Added 2022-01-26 15:00:10 +0000 UTCWe all know friction in a mechanical advantage block and tackle pulley systems can reduce output, but I haven't heard anyone talk about stretch. I am always using semi static or climbing ropes, which have a lot of stretch. We test all the way up to a 13:1 with dynamic, semi static and 0 stretch dyneema. We did NOT use multipliers or brakes to simplify this already long experiment. *All numbers are in kN. Trying to keep a lot of data easy to look at!
►►►DYNAMIC ROPE ►1:1 pulleys n/a - 1.34 INPUT x 1.19 OUTPUT / 100% vs Actual 88% ►3:1 with pulleys - 1.13 INPUT x 2.26 OUTPUT / 300% vs Actual 200% ►3:1 without pulleys - 1.19 INPUT x 1.99 OUTPUT / 300% vs Actual 167% ►5:1 with pulleys - 0.89 INPUT x 3.84 OUTPUT / 500% vs Actual 431% ►5:1 without pulleys - 1.39 INPUT x 2.38 OUTPUT / 500% vs Actual 171% ►9:1 with pulleys - 0.85 INPUT x 5.92 OUTPUT / 900% vs Actual 696% ►9:1 without pulleys - 1.12 INPUT x 2.38 OUTPUT / 900% vs Actual 212% ►13:1 with pulleys - 1.01 INPUT x 5.04 OUTPUT / 1300% vs Actual 499%
►►►SEMI-STATIC ROPE ►1:1 pulleys n/a - 1.62 INPUT x 1.26 OUTPUT / 100% vs Actual 78% ►3:1 with pulleys - 1.31 INPUT x 3.46 OUTPUT / 300% vs Actual 264% ►3:1 without pulleys - 1.72 INPUT x 2.48 OUTPUT / 300% vs Actual 144% ►5:1 with pulleys - 1.10 INPUT x 5.15 OUTPUT / 500% vs Actual 468% ►5:1 without pulleys - 1.18 INPUT x 2.67 OUTPUT / 500% vs Actual 226% ►9:1 with pulleys - 1.31 INPUT x 7.48 OUTPUT / 900% vs Actual 696% ►13:1 with pulleys - 1.4 INPUT x 6.98 OUTPUT / 1300% vs Actual 498%
►►►DYNEEMA ROPE ►1:1 pulleys n/a - 2.33 INPUT x 2.07 OUTPUT / 100% vs Actual 89% ►3:1 with pulleys - 1.34 INPUT x 4.04 OUTPUT / 300% vs Actual 301% ►3:1 without pulleys - 1.47 INPUT x 2.97 OUTPUT / 300% vs Actual 202% ►5:1 with pulleys - 1.67 INPUT x 6.71 OUTPUT / 500% vs Actual 402% ►9:1 with pulleys - 1.47 INPUT x 9.62 OUTPUT / 900% vs Actual 654% ►13:1 with pulleys - 1.51 INPUT x 8.54 OUTPUT / 1300% vs Actual 565%
►►►THOUGHTS: *** % wasn't that different but my input is so much greater not fighting stretch ***9:1 is better than a 13:1 and might be worth using, but a 5:1 is the most optimal to get as close to theoretical as possible
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00:00 Its a Myth! 01:34 Dynamic Rope 04:53 Discount! 06:05 Semi Static Rope 07:54 Dyneema 10:46 Applying the science! 13:03 Conclusion! 14:34 We found it!
Comments
Will try to do a complete comparison with all biners of that type soon
Jason
@HowNotTo Ryan, Dude. I have to hook you up w/ a handful of DMM Revolvers. Hit me up. I keep looking at all this, and like, who keeps that many pullies around? But the revolvers are useful as just carabiners w/ less friction for everything carabiners are used for. Maybe not as good for either, but I'd love to see tests done w/ them.
