Abstract: A mobile ballast cleaning machine comprising an endless ballast conveying chain movable in a conveying direction, the chain having arranged sequentially in the conveying direction a transverse chain section for excavating the ballast, an upwardly extending elongated chain section for conveying the excavated ballast, the upwardly extending elongated chain section being supported in a guide of channel-shaped cross section and having a bottom defining a plurality of ports for pre-screening the conveyed ballast to separate waste therefrom falling through the ports in the bottom, and a descending elongated chain section leading to the transverse chain section. A vibratory screen is arranged to receive the pre-screened ballast from the upwardly extending elongated chain section to separate residual waste therefrom, a cleaned ballast component remaining on the screening means and the residual waste falling therethrough. A conveyor conveys the waste away.