Abstract: The opening and closing device permits simultaneous opening of for instance 100 m long roof hatches. Gear wheels are permanently mounted in housings on a transverse driving shaft at regular intervals. The gear wheels drive their respective rack for simultaneous displacement of the entire window. The cogs of the gear wheel have a larger width and are thin compared to the corresponding measurements of the rack cogs. In order to ensure the gear wheel mesh the rack comprises supporting surfaces engaging the cylindrical surfaces of the gear wheel and support rolls. This device ensures that the racks hinged to the window frames may be displaced along or turned about their engaging points with the gear wheel without disengaging said gear wheel, and in such a manner that squeezing is avoided in connection with the longitudinal stretching and shrinking of the shaft due to variations of the temperature.