
Human-powered cranes - cjg
http://www.lowtechmagazine.com/2010/03/history-of-human-powered-cranes.html
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Animats
Human powered cranes are quite common, in sizes up to a ton or two.[1] Most
large auto shops will have one sized for engine removal. Overhead rail and
chain fall systems are common.

The biggest hand-cranked crane-like devices ever built were probably the
Panama Canal emergency dams.[2] This was a backup system in case a ship
damaged all three gates of the top locks and let the lake pour through. The
emergency dam could stop that.

It was a swing bridge long enough to swing across the canal, and although it
could be operated electrically, it was also hand-crankable. This was regularly
tested. The bridge was cranked out across the canal, above the water. Then
wicket girder assemblies were cranked down into the water until they locked
into slots in the lock floor. Then, one at a time, metal plates were dropped
down tracks in the wicket girders, each one blocking more water, until all the
plates were in place and the flow stopped.

They were never needed, and were dismantled decades ago.

[1] [http://www.northerntool.com/shop/tools/category_material-
han...](http://www.northerntool.com/shop/tools/category_material-
handling+hoists-lifts-cranes) [2]
[http://engineering.dartmouth.edu/magazine/inventions-
panama-...](http://engineering.dartmouth.edu/magazine/inventions-panama-canal-
emergency-dams/)

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HeyLaughingBoy
Way back in the late 80's/early 90's I visited the USS Intrepid, a WW II
carrier converted into a floating museum in Manhattan (to those in NYC: if
it's still there it's well worth the visit).

Anyway, one of the (many) things that really impressed me was how easy it was
to move the multi-ton antiaircraft gun turrets with just a hand wheel.
Mechanical advantage FTW!

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logicallee
This article was very fascinating. Some of the weights mentioned seem
incredible, but it seems to know what it's talking about.

If you read all the way to the end you get an interesting angle -- this isn't
just a historical piece! Then if you click through to the main page of the
site it's on, it's bizarro world, like a news source that is the opposite of
hacker news in readership, outlook, and what it celebrates. (Way more than you
would think given the article in question.)

I'm glad to have read it!

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jacobolus
I found this video speculating that the pyramids were built by floating the
blocks in water kind of interesting:
[https://www.youtube.com/watch?v=C1y8N0ePuF8](https://www.youtube.com/watch?v=C1y8N0ePuF8)

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vlehto
Interesting.

The biggest problem would have been making those gates completely watertight.
The design on the video cannot be that.

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clock_tower
Very interesting information. I hadn't known about the late-19thC cranes;
compared to them, contemporary ones look a bit under-engineered.

Of course, that doesn't mean that we should go back to manually-powered
treadmill cranes -- there's some discussion of that in the comments -- but it
sounds like we could build engine-driven cranes that would perform much better
than the ones we currently have.

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HeyLaughingBoy
Modern cranes look under-engineered precisely because they are properly
engineered.

We have the ability today to do much better structural analysis than in the 19
century so a device can be built with much less material than required then.
We can build a mechanism with just enough material to provide a known 10x
safety factor. Back then they had no choice but to overbuild to be sure that
there was adequate margin.

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Lilecomman1990
Some treadwheel cranes survived:
[https://en.wikipedia.org/wiki/Treadwheel_crane#Surviving_exa...](https://en.wikipedia.org/wiki/Treadwheel_crane#Surviving_examples)

