The oldest Allen Bradley pots you may ever see

Bradleyometers.  Early 1930's.  Big.  Linear element with geared sweeper. 

Sure that metal backed one is a fake; Indonesia 2013 for the Western Electric market 

Man, if these have taken off in vintage world, I missed it! 

I found these in an old radio shop guys' estate piles, pretty sure I've never seen another, or one in anything.  You do find print ads for them in old mags. 

Patent Applied For-- the real mojo!!

You know the disks come out? You can scramble them for different tapers.

I wish they would re-issue these things new.

I think I knew and forgot that, an article way back when maybe?  The hi-fi people should be all over that custom taper approach.  Wonder what the unit price would be?  Less than a Shallco, maybe not an Elma. 

Interesting. "Bradleyometer" seems to have been a name for several different devices.

Bradley had long been making large carbon compression variable resistors for motor control.

A BradleyStat is a 2-terminal carbon-disk compression resistor typically used for filament power control (that's how they dealt with both battery fade and volume control in the day). The design naturally offers an "off" position when the pressure falls past zero to slack/gap.

The first Bradleyometer, ~~1923, seems to be *two* stacks of carbon disks with a cam to compress one and decompress the other, giving a 3-terminal potentiometer (more or less).
https://books.google.com/books?id=vd7mAAAAMAAJ&pg=RA3-PA75&lpg=RA3-PA75&dq=Bradleyometer&ved=0CC0Q6AEwAQ#v=onepage&q=Bradleyometer&f=false

In 1936 we have the Type J which is a now-conventional construction except the resistor is "a solid molded ring, not a film".
http://www.americanradiohistory.com/Archive-Radio-Engineering/30s/1936/Radio-Engineering-1936-01.pdf (page 3 of 2MB PDF)

I know I have seen a full-page ad for the type you have, but can not remember where. But the types I can find suggest yours is somewhere in the 1924-1935 period.

Wow, that first Bradleyometer.  My example pales.  I would guess noise performance might be atrocious in certain conditions, maybe not. 

what kind of contact cleaner would you recommend for these relics?

They are so heavy duty I might describe them as 'self-burnishing'. 

Thanks for posting these - I too get a kick out of seeing that sort of original technology.

Jakob E.

No machines making those!

There's an ad for the BradleyStat on pg 84 from PRR's link.