The bar rack is installed across the pit. The rake is normally parked in its top position above deck. The comb is disengaged from the bar rack. When a signal is received, the rake travels downwards, directed by the wall guides. On reaching the bottom, the rake tilts from its open position to its raking position. The rake tines penetrate between the bars of the rack. The rake travels up-wards collecting and storing the debris. When the rake reaches the top, above deck, it tilts and the water brought up by the rake scoop flushes the debris away into the deck flume.