Who was Oldham (as in Oldham Coupler)

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:

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?

Reading this just makes me feel old cause I remember when the R-390A was the Navy's premier state-of-the-art SSB receiver, and that was in the SIXTIES!!!

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:

-- Bob (Chief Pilot, White Knuckle Airways)

That's a real classic! Couldn't get your link to work, so I put a scan here:

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

LP posted:

"Reading this just makes me feel old cause I remember when the R-390A was the Navy's premier state-of-the-art SSB receiver, and that was in the SIXTIES!!!"

If being an R-390A user makes you feel old, having been a member of design team of the T-368 transmitter that accompanied the R-390A in the Army's GRC TTY communications vans, then I must be ANCIENT! ! ! ! !

Actually, the R-390A is still a very competitive receiver commanding very high prices on eBay, perhaps second only to the Collins 75A4 (whose design is heavy based on certain sections of the R-390A). At the time (circa 1960) many firms tried to duplicate the R-390A's variable frequency local oscillator but failed because no one could figure out a production alignment methodology that would produce the same frequency linearity as did the Collins produced LO unit. (At least at B&W we couldn't.) This involved the precise bending of a capacitive loading finger strip that paralleled a rotating, variable inductance coil and compensated for a small amount of tracking error in the coil's windings.

The old 'boat anchor' receivers still hold an advantage over most of the current generation of solid state units -- That is, when they break you can fix them yourself! :-)

IIRC, two versions of the R-390A were produced, one with a conventional tuning dial and the other with a geneva mechanism type counter showing the tuning setting but not the frequency. The receivers were produced by a number of firms, but so far as I know all of the LOs in them were manufactured by Collins Radio.

Ah, memories....

Harry C.