Link 4 has screw thread on which nut 5 is screwed. When nut 5 is turned clockwise (screwed on) link 4 is pulled upward. Double-bevel recess a-a in link 4 engages the bevelled end of link 3 pushing it in the horizontal direction. At point A link 3 pushes lever 2, turning it about fixed axis B to clamp workpiece 1.
$2198$WL,GC$