Abstract: A chisel for a crust breaking facility for breaking through the solidified crust of electrolyte on an electrolytic cell, in particular a cell for producing aluminum, is such that at least a part of the edge region on the bottom face of the chisel projects out beyond the other regions and is in the form of cutting edges. The bottom face of the chisel features no faces which are inclined outwards and would create outward directed forces as the chisel is forced through the crust.The chisel of the invention allows energy and investment costs to be reduced.

Abstract: The invention relates to a chisel alignment unit for a facility for breaking the crust of solidified electrolyte on an electrolytic cell, in particular on a cell for producing aluminum. A mechanically stable alignment box extends from the under side of the chisel in its non-working position to the piston rod. The chisel features at least one vertical alignment surface which is in contact with at least one alignment roll mounted on the alignment box by means of roller bearings. A wiper for removing electrolyte from the chisel is mounted below the alignment rolls and extends over the full width of the alignment surface or surfaces.