Abstract: A cleaning apparatus for cleaning a cooling tube array of a heat exchanger, including a triangular truss beam supported to be movable in a first direction, which direction is perpendicular to a longitudinal direction of the truss beam, a nozzle carriage movably held on the truss beam, the nozzle carriage being movable along the longitudinal direction of the truss beam, and a plurality of cleaning nozzles mounted to the nozzle carriage, the truss beam having two tubular top chords and one tubular bottom chord that is arranged centrally below the top chords, and bracings that connect the chords, and the nozzle carriage having at least one bottom chord roller that is arranged for traveling on the bottom side of the bottom chord; and a cleaning apparatus having a square truss beam.