Abstract: A shredder for brushwood and the like (FIG. 1) has at least one shaft carrying a helically arranged array of cutting discs surrounding the shaft. The discs are individually fixed on lugs which are generally radial to the shaft. As the brushwood is fed along generally parallel to the shaft axis it is impacted by the cutter discs, acting against one another where two parallel shafts are employed, or between the discs and a surrounding chamber wall if only a single shaft is employed. The shredded material is further fed and exhausted through a delivery passage by a current of air induced both by the discs and also by fan vanes carried by the shaft. The advantage of the discs as cutters is that if and when worn or blunted, each can be adjusted angularly on its lug to present a fresh portion of its periphery for action, without it being necessary to immediately replace or re-sharpen it.

Abstract: A wood-chipping machine (FIG. 1) has a plurality of cutters carried by a flywheel which is rotated to move the cutters across a throat through which material to be chipped is fed, and in which each cutter is substantially frust-conical and hence circular and a plurality of such cutters form a blade at a generally radial location of the flywheel. These facilitate blade replacement in the event of wear eg by adjusting the worn cutter angularly.