Nut 1 is connected by a screw pair to stud 4 which is screwed tightly into the base. Stud 4 passes through hole a in link (clamp) 3 with a clearance. Workpiece 2 is clamped by link 3 upon tightening nut 1. When the nut is released, spring 5 raises clamp 3 to its initial position.
$184$SL,GC$