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Comment by araes | Hacker News Reader

If the author reads this, since it's from 2020. The author appears to be currently investigating knot physics and drop tests.

However, the author does not "appear" to have the Luff Tackle variation. [1] I think it's close to the 6:1 variation on row two, except with the pulley directly attached to the ceiling.

The systematic approach seems to work, just appears to be missing a few combinations, or it was not really systematic. Such as, their should probably be a lot of pulley combinations that are basically "nothing", or "not helpful" combinations. 1:1, or 1/2:1, ect... combinations that just noted as discarded (or maybe curiosities that "might" have a use)

A 1:1 pulley is not "technically" significant from this perspective, yet it does change the force direction.

[1] https://en.wikipedia.org/wiki/Pulley#Method_of_operation

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The 4th item in the top row of the first image is the Luff Tackle, using the authors rule that you can invert any combination and subtract one from the advantage; the non-inverted shown in TFA is 1:4 and the luff tackle is inverted and 3:1.

Cool, thanks. Why I said "appears". Figured I was probably missing something. Author has spent way more time on pulleys.

1/2:1 is not useless. Sometimes you want to pull a rope quickly and power is not a problem. One real world use of a 1/2:1 pulley system is in high performance sailing dinghies on the spinnaker halyard. You want to be able to hoist it as quickly as possible, before the wind puts pressure on the spinnaker.

Just about every forklift uses a 1/2:1 pulley system in the the chains that lift the fork carriage up the mast. The main lifting pistons push a pulley upwards with chains tied to the fork carriage and mast base routed through the pulley.

Maybe I don't understand what you're describing. That sounds like a system where you'd prefer slow, and really heavy lift capacity?

Thanks. Figured there might be something, why the "might" have a use.

Maybe it's implied, yet the author didn't seem to care about fast, and mostly appeared to be counting whole numbers for greater lift. Guess most of the furthers probably also have uses if force is not an issue 1/3:1, 1/4:1, ect...

Sailing's not one I'd thought of much. Guess if large scale sailboats ever make it around again, hauling large scale ripstop nylon clipper sails might use a really fast spinnaker halyard.

Really fast lines are used to drop spinnakers on big boats: https://www.youtube.com/watch?v=MiAo3KQ89no - this uses gears more than pulleys but same idea, light loads and high speed.

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