Link 1 is connected by screw pair A to lever (sliding clamp) 2. Tip a of link (screw) 1 slides along slot b of the base. Bolt d passes freely through slot f in clamp 2. The clamp is supported by spring 4 through washer e. Workpiece 3 is clamped by lever 2 when link 1 is screwed in. Spring 4 returns lever 2 to its initial position.
$191$SL,GC$