Explain the differential; make them deferential.

Today’s engineering lesson of the day brought to you by the 1930s. You might be familiar with this problem if you, as a kid, ever tried to drive a toy car around a turn and the wheels scraped along the floor and made that horrible noise plastic makes when it scrapes.


Why can’t Discovery Channel do more like this? (skip to 1:50 to get to the actual tutorial)

Very interestingly, devices like this have apparently been around for thousands of years. Considering it’s under the wiki for “Differential,” which is a more general term for something which does a similar job, it probably wasn’t this specific sneaky set of gears in the video above. But they were used for something called the South Pointing Chariot (in China, they were used as compasses way way back in the day), so they may well have been a very sneaky set of gears.

Image of a rear-axle differential

Not as complicated as it might look.

It’s been said that science is the act of trying to find something nobody yet understands, and explaining it in a way that everyone can understand, and poetry is the act of trying to find something everybody understands, and explaining it in a way that nobody can understand. The poetry part you can take or leave, but this is a pretty solid principle for science.

Engineering, being a kind of science, requires more than tricky knowledge and invention. It requires one to be able to explain the concept simply. This video is really elegant in that way. Whoever came up with this solution (whether it was three thousand years ago or 80) was very sly, good with gears (read: lots of trigonometry), and was probably persistent, but if they couldn’t explain what they did like this video does, nobody would understand why their invention is useful!

So basically, part of being a brilliant engineer is being good at showing people just how brilliant you are. That’s today’s engineering lesson of the day.

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One thought on “Explain the differential; make them deferential.

  1. Pingback: Get Real - Spiders have too many legs… this robot has too few

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