Abstract: The invention relates to a clamping cylinder for operating, for instance, a chuck by means of a pull pipe or pull rod installed preferably in a turning machine. The clamping cylinder has a cylinder casing (4) comprising a screwed-on cover plate (5), an axially displaceable piston (12) in the work chamber (11) of the cylinder casing (4) to produce the clamping force and a distributor (2) fixed onto one of the cylinder casing faces with ports and pressure lines for supplying and discharging a pressure oil to and from the work chamber of the piston. According to the invention, the cylinder casing (4), its lid (5) and the distributor casing are made of a light metal in order to reduce inertia moments and wear and to improve lubrication and heat dissipation. The walls of the locating bores for the piston (12) and/or its piston rods (13, 22) are hard coated. The piston and its two piston rods are made in a single piece from a tool steel and their respective contact surfaces are hard chrome coated.