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Human-powered cranes (lowtechmagazine.com)
62 points by cjg on Nov 3, 2015 | hide | past | favorite | 9 comments



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... [2] http://engineering.dartmouth.edu/magazine/inventions-panama-...


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!


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!


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


Interesting.

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


Pyramids are built of concrete - low tech technology (fire+water only) know for thousands of years.


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.


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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