Patent ID: 8784038

Claim:
A cutting assembly comprising: a) a drive shaft alternately rotatable in a first direction of rotation and a second direction of rotation; b) a rotary cutter rotatably fixed to said drive shaft; the rotary cutter comprising a circular hub having a bore through a central axis of the bore, and an implement for fixing the drive shaft within the bore; a plurality of cutting lobes, each of said cutting lobes having an upper surface, a lower surface opposite to the upper surface, a leading edge and a trailing edge opposite to the leading edge; each cutting lobes having an aperture therethrough extending from and through the upper surface to and through the lower surface; each of the cutting lobes extending outwardly from the hub such that a center line equidistant between the leading edge and the trailing edge of each cutting lobe is substantially perpendicular to the central axis of the hub; the cutting lobes being distributed around a periphery of the hub such that each of the distances from the leading edge of each cutting lobe to the trailing edge of a next adjacent cutting lobe are substantially equal; the upper surface of each cutting lobe having a convex curvature extending from its leading edge to its aperture and from its aperture to its trailing edge; the lower surface of each cutting lobe having a plurality of grooves and a dividing wall between adjacent grooves, the grooves and dividing walls of each cutting lobe extending either from its leading edge to its trailing edge or from its leading edge to its aperture and from its aperture to its trailing edge; each of said grooves having the shape of an arc of a circle which is concentric with the central axis of the hub; c) a circular plate cutter for mounting to an intake opening of a stationary volute, said plate cutter having a central plate bore, and a surface having a plurality of concentric grooves and a dividing wall between adjacent grooves; each of said grooves having the shape of an arc of a circle which is concentric with the central axis of the hub; the drive shaft being mounted for rotation within the plate bore; the plate cutter having a plurality of holes through its surface; the grooves and dividing walls from the lower surface of each cutting lobe being juxtaposed with corresponding dividing walls and grooves from the circular plate cutter.