Apparatus and process are provided wherein pressure is exerted on a web by at least two rollers. One roller includes a roll shell which is rotatable around a stationary beam, wherein the roll shell is supported against the beam by hydraulic operational support elements on the side of the press, as well as by counterpressure elements exerting pressure in the opposite direction. A particularly rapid and safe opening of the roller device, without damaging the supporting elements or the roll shell because of detached supporting elements, is achieved because the hydraulic pressure medium from the pressure areas of at least part of the operational support elements is routed as directly as possible without detours to the pressure areas of counterpressure elements, such as by a multiple sliding valve located at the beam end.