Heavy Pot & Heavy Gear Shaped Thing

Bought this pot; no handle on the lid

And with the pot, came this

That gear thing weighs almost 2 kg.
I didn't weigh the pot yet, but if I'm not mistaken, the seller said the total weight was 7 kg.

Don't know if the 2 belong together, but the gear thing does fit rather nicely in the center circle of the lid

I didn't manage to find a similar pot online. And when Google Lensing the gear thing, Lens shows table shaped like that...

Any idea what type of pot this is, and if the 2 items belong together?

 

Ha! Found the answer!

It's used to produce/test paper!
https://www.thuenen.de/de/fachinsti...der-und-labore/papierherstellung-und-pruefung

 

Who'd have thunk!

 

According to the (German) image name, these are 'Mahlaggregate'

Still no idea how it's used...

 

Well it's cool so I had to go look too. One part of your link translated as Jokro Mill and this site shows what look like might be like yours, a Jokro Refining Mill in use.



Equipment for refining pulps in standard conditions. Equipment with 6 independent refining devices for 16 grams of paste/pulp. It allows us to analyze more or different pastes under similar refining conditions. Mainly used in Eastern European countries. Refine small amounts of paste.
https://www.idmtest.com/products/jokro-refining-mill-pta

 

I had searched for the different devices that they mention, starting with that mill. Saw the image, but never imagined it would have the pot inside of it, so I skipped to the next device...

 

https://paralab.pt/wp-content/uploads/2020/01/Catálogo_-Moinho-de-Jokro_Frank-PTI.pdf
PRODUCT DESCRIPTION
The Jokro mill, based on technology developed by Jonas/Kross, enables laboratory scale, standards-compliant and reproducible beatings of pulp, using the principle of centrifugal force. Six rolls revolve around their own axes, like planets, within special beater housings. At the same time they orbit a central pivot point. The pulp
is beaten between the inner wall of the housing and the cylindrical roll. This principle guarantees the most consistent possible beating load.
TEST DESCRIPTION
A weighed pulp sample prepared with a standard-compliant disintegrator is added to the individual containers. Each roll is placed within a beater housing, and each housing is closed with a cover. After inserting the containers (2, 3, 4 or 6 of them), the safety cover is closed and the beating process is started. The mill stops automatically when the preset time or number of rotations is reached. The current number of rotations is shown on the display.
The container is removed after the beating process has ended. The freeness of each sample can then be determined with the Schopper-Riegler Freeness Tester.