Check out the latest addition to my ⁨⁩ ⁨⁩ collection! This is a Marchant "Silent Speed" 8D from 1940, a fast electromechanical analog calculator that can even infinite loop if you divide by zero. I'll be refurbishing it this weekend to make it fully functional.

Anyone interested in mechanical engineering should definitely check out the *analog* carry mechanism in these Marchant calculators that relies on planetary gears. These Marchants are arguably the high water mark for electromechanical calculator engineering.

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From John Wolff's museum:
"The Marchant "Silent Speed" and its descendants use a complex and unusual continuous-drive mechanism based on proportional and differential gearing. Every column incorporates a ten-speed gearbox with three drive shafts and five selectors. The accumulator tens-carry mechanism is contained within the carriage, using a differential gearing mechanism with two planetary gearsets per digit."

See also Jaap's pages:


@EdS I relied on John Wolff's documentation when I was attempting to repair a previous Silent Speed. Incredibly complex machines. The official service manual just had drawings and it was handy to see high-quality pictures of the mechanisms.

@EdS Cf. Neal Stephenson's "rod logic" from The Diamond Age.


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