Abstract: The invention relates to a door drive system for a wing of a door, a window or similar, comprising a housing with a drive and/or return device, e.g. a closing spring (7), and a preferably hydraulic damping device. In practice, drive housings of this type are cast in aluminium. The production costs are relatively high since housing openings and boreholes such as hydraulic channels have to be cut into the housing (31) later on. According to the invention, the housing (31) is produced wholly or partly from plastic. This enables the cavities which are necessary for the housing to function, such as housing boreholes and/or openings to be made in the drive housing when it is produced, without removing material by cutting. According to another design, the drive housing has several housing parts which are produced separately. The adjacent sections of the housing parts are then stuck or welded together.

Abstract: A door actuating system for the leaf of a fire door includes a safety fuse that detaches the fixture between the housing of the door actuating system and an arm on the door or the door frame, which then falls on the floor and are no longer in contact with the hot surface of the door. Plastic screws and plastic bushings accomodating metals screws or assembly plates made of plastic or similar materials can be used as the safety fuse.

Abstract: A hydraulically damped door closer is described which has a relatively weak closer spring (3c) and stronger back-up closer springs (3a, 3b). If, after a predetermined time period, the door does not arrive in the closed position under the effect of the closer spring (3c), the back-up closer springs (3a, 3b) are connected for the closing. Their connection is therefore controlled by way of a time function element, which represents a simple and, at the same time, reliable control.