with respective lateral flanges 3 at which the trunnions abut against the respective lateral faces of sleeve 1 the roller sleeve 1 is bottom cast in a vertical cast with a tangential mold after the molding of the sleeve central bores are drilled therein from two lateral faces thereof towards each other the sleeve 1 made out of cast iron is comprised at the most of the radial extension thereof of gray cast iron which only at the outer edge area changes over into white cast iron trunnions 2 which are also cast molded are then finished in the usual fashion and bolted to the lateral faces of roller sleeve 1 by means of bolts 4 an inlet passage 5 and an outlet passage 6 for a heat conducting liquid extend respectively trough the trunnions 2 which lead to and from the interior of the roller it is of course understood that inlet and outlet passages in two trunnions 2 can be interchanged the interior hollow space of the roller is filled with a two part push away or displacement member 50 formed of two even halves 7 and 7 39 which are in the middle pushed towards each other each half of the displacement member 50 includes a cylindrical portion 8 of sheet metal which is closed at two ends thereof with end plates 9 and 10 extended transversally to the elongation of the cylindrical portion and tightly welded thereto at the inner surface of that portion each half.