Nut 1 is connected by screw pair A to fixed bolt a and has a cap with tip b which slides along lever 5. Lever 5 turns about fixed axis B and at point C depresses link 6 which is supported by spring 4. Links 7 are connected to link 6 by turning pairs N and K, and to links (clamps) 2 by turning pairs L and M. Clamps 2 turn about fixed axes E and F. When nut 1 is unscrewed, lever 5 depresses link 6. The motion of link 6 is transmitted through links 7 to clamps 2 which clamp workpiece 3. The forces exerted by the two clamps are equalized. Spring 4 returns clamps 2 to their initial position when nut 1 is screwed on bolt a.
$189$SL,GC$