How is this joint (robot arm joint) arranged?

Question

Do it yourself

I can't understand how this connection is arranged in the robot arm from the movie How it's made (Discovery):

In the video, the arm can move the claw up and down, as well as rotate the claws around its axis. Is it possible to make these turns at the same time? What is this type of connection called?

Answer 1

If I understand correctly, then two parallel gears rotate independently of each other. If they rotate in the same direction with equal angular velocity, then the horizontal gear will turn up / down. If in opposite directions with equal angular velocity, then the horizontal gear will rotate around its axis. By combining the angular velocities of the vertical gears and their directions, it is possible to simultaneously move up/down and rotate the horizontal gear.

Answer 2

It reminded me of a differential.
youtube.be/yYAw79386WI