are held by two hydraulic cylinders 10 which act on the two mounting faces of the bottom roller with the aid of stops against which pistons of the hydraulic cylinders 10 work the bottom roller is held in a predetermined position in case of a paper tear or to exchange a roller the hydraulic cylinders 10 are made ineffective so that all rollers 2 and 3 with the exception of the top roller can be lowered to the degree necessary in the lowered position the rollers 2 and 3 are held by hanging spindles not shown supported from the calendar frame 4 the weight of the rollers 2 and 3 because of their vertically shiftable mounting produces a minimal pressure in the roller nips this pressure can be increased with the aid of a loading device which acts on the top roller with a downward force and in the exemplary embodiment consists of two hydraulic cylinders 11 which are capable of exerting small increases of downward force on the two mounting faces of the top roller the functional dependence between smoothness and minimal pressure can be found empirically for each kind of paper based on this dependence the computer calculates the values for temperature and moisture as shown in fig2 a pressure regulating valve 14 or 14 39 lies in each of the lines leading from a pump 12 which is driven by a motor 13 to the two hydraulic cylinders 11 by means of which it is possible to control the load force of the two hydraulic cylinders 11 in nine stages independently of.