I have attached a screenshot with the joints. There is a motor that outputs translational motion, and when it pushes the bottom of an arm (TranslationalArm) forward, that arm pivots about its center, and the top of the arm then pulls the bracket (LeftBracket) it is connected to back. That bracket is connected to another bracket by two arms, so when that bracket rotates backwards, the other one does as well.
You are navigating away from the AIS Discovery experience