All mechanical engineers know the name of the person who invented the joint, as their common sense. I saw this connection type But I didn’t know who invented.
Sightron’s ALT-AZ mount uses the Hirth Joint, which allows to adjust the ALT arm angle while still maintaining the solid connection. This is a really practical and reliable joint indeed. (BTW, EMCAN Mount has the Hirth Joint too)
Pointing to the zenith? No problem!