Human-powered cranes

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-...

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!

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.