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Truck driver guide.
https://diqn32j8nouaz.cloudfront.net...e_fullsize.jpg
Previously:
https://www.homemadetools.net/forum/...895#post206795
https://www.homemadetools.net/forum/...706#post206104
https://www.homemadetools.net/forum/...863#post206650
https://www.homemadetools.net/forum/...206#post207874
https://www.homemadetools.net/forum/...416#post204737
Seldom you see a fundamental error in a poster of this nature. The multiplication factor from the tension pulling on the rope to the tension pulling up on the load is two for this arrangement, not three. In the idealized pulley example in the upper right corner note that there are two rope elements at 10 lb. tension pulling up on the 30 lb. weight, not three. The weight would not move up from its rest position. The final rope element to the invisible hand putting 10 lb. tension on the rope is merely changing direction over the pulley so the person can pull down instead of having to pull up if the pulley were absent. Note, however, that the multiplication factor to the tension on the rope element above the pulley is, in fact, three because there are three rope elements at 10 lb. tension pulling down on the hitch.
Not criticizing the value of this arrangement. I use it all the time to secure loads except I'm in the habit of using an "artillery hitch" instead of a marlin-spike hitch to form the loop simply because that's the way I learned it 70 years ago. Equally simple to tie and easy to untie after putting tension on it. If it was good enough for Alexander to have many men pulling artillery over the alps it's good enough for me.
I shouldn't have been so snarky in my prior post. I was observing the 30 lb. weight in the idealized example and assuming the poster was referring to lifting the weight. Referring to putting tension on the rope above the hitch going over a load you do get a multiplication factor of three, as stated.
Well actually your first comment would be correct from the perspective of the pipe being the load however if you consider the pipe as the side rails of a trailer and the fixed upper end pulling on a tarp then it would be a 3 to 1 shown in the attached pictureQuote:
Originally Posted by awright
the first diagram is 1to1 second is 1to1 3rd is 2 to 1 and 4th is 3 to 1
Attachment 43329
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