Nut 1 is connected by a screw pair to fixed stud a which passes through lever 2 with a certain clearance. Lever (clamp) 2 is supported at its lower end b by button c. Workpiece 3 is clamped by clamp 2 when nut 1 is tightened. When the nut i s released, spring 4 returns clamp 2 to its initial position.
$187$SL,GC$