A drive apparatus for a drill stem of a de-coking system is disclosed. The apparatus includes a feeder as water supply to the drill stem. The drill stem is rotatably driven by a rotational drive which includes a motor and a first and second gear box. The second gear box has an output gear which is meshed with a large gear which is connected to an outer gear rim of the feeder. A skirt envelops the gear which is formed by an output gear and by the second motor driven gear box and the gear which is connected to the feeder completely. A lower side of the skirt is open.