Device for producing and/or processing panels includes a panel transport device utilizing two double-belt conveyors for transporting panels along a transport path. A processing device is used for processing the panels during their transporting by the panel transport device. Each of the two double-belt conveyors includes an upper endless belt and a lower endless belt having transport strand sides essentially parallel to the transport path and deflection devices arranged to at the ends of the transport strand sides. A plurality of guide rollers are arranged between the deflection devices of at least one of the endless belts to support the transport strand side of the at least one endless belt. At least one roller cassette is arranged to support several of the plurality of guide rollers.