An "Oldham Coupler" is way to transfer torque between two parallel but not-quite-collinear shafts. It has three disks, one coupled to the input, one coupled to the output, and a middle disk that is joined to the first two by tongue and groove. The tongue/groove on one side is perpendicular to the tongue/groove on the other. Often springs are used to reduce backlash of the mechanism. The coupler is much more compact than, say, two universal joints. But: who was Mr. Oldham? Google searches turn up the device's inclusion in R-390A radios and astronomical instruments, but nothing about its inventor. Tim. (who otherwise wonders who takes care of the caretaker's daughter while the caretaker's busy taking care.)
Who was Oldham (as in Oldham Coupler)
Jun 05, 2005
12 Replies
Darned good question, and I couldn't find a trace of the inventor either.
Maybe they were first produced by a company in Oldham, England?
FWIW, now that you got me hooked, does the design minimize angular rotation "distortion" when used on offset but parallel shafts, similar to the way a pair of crossed (i.e. offset 90 degrees to each other.) universal joints will?
Jeff
Dear shoppa:
Don't concentrate on the words that are not necessary in your search, or use alternatives. Requiring both words oldham and mechanism, I get this hit: URL:
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which points to Oldham, John URL:
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David A. Smith
If you ignore such inconveniences as backlash, flex and friction then the Oldham coupling should have no angular rotation distortion -- because regardless of the linear offset the middle disk's angle will be fixed to both end disks by the slot and groove arrangement.
Of course the same is true for crossed U-joints; the question would be which one does better in practice?
Knight's "American Mechanical Dictionary" of 1872 says that it was invented by Oldham...So it goes back a ways.
Tom
Bravo David!
You da man!
Jeff (Who refuses to admit how long I tried to find the answer earlier today...)
Hey Tom,
Do you have a copy of Knight's Dictionary? I have one too. Three volumes. A great set of books. I bought mine from an antique store in Wales when I was in graduate school in the 70's. Great fun to look through. Whoever had my copy originally was involved in the shipping industry. He made a lot of pencil notes in the margins for listings related to steamship design.
This is my favorite plate:
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listed under "Battery Gun".
-- Bob (Chief Pilot, White Knuckle Airways)
That's a real classic! Couldn't get your link to work, so I put a scan here:
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Tom
My link was screwed up somehow. I don't have time to fix it tonight. Your scan is better than mine, anyway. Mine came out too dark.
I always thought this pic looked like it was of an early Al Qaeda training site. Where did you get your set of Knight's?
-- Bob (Chief Pilot, White Knuckle Airways)
Lions book sale, $5 :-)
Tom
John Oldham - Ireland, early 1800s. Egraver, toolmaker, and general genius.
Those are often used in high voltage to shaft adapters - fiber length to a steel through to knob. Seems I have some - stainless... The Web only contains those who someone already thought of or who is remembered.... Maybe this is your shot to generate a web page.
Martin
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