When piston 1 is moved to the left by the action of fluid delivered to the righht end of the cylinder, wedge 2, mounted rigidly on the end of the piston rod, actuates roller 3. This turns lever 4 about fixed axis A to clamp workpiece 5. Workpiece 5 is released in the return stroke of piston 1 to the right when fluid is delivered to the left end of the cylinder.
$3872$LHP,GC$