Abstract: The object of the invention is an apparatus for clamping a chipper knife (1) to a rotatable chipper disc (4) or drum so that the back surface (6) of the knife (1) is supported against a knife clamp (2) with a knife spacer (3), and that the knife clamp (2) and knife spacer (3) are movable relative to each other by means of the clamping element (5). The knife clamp (2) is provided with supporting surfaces (11, 12) which the back surface (6) of the knife (1) is adapted to lean against by at least two spaced-apart surfaces (11', 12'). The knife spacer element (3) includes a supporting surface (13) which is adapted to subject a front surface (14) of the knife (1) to a force acting between said supporting surfaces (11, 12) of the knife clamp (2) for bending the knife (1) between said supporting surfaces (11, 12) of the knife clamp (2) towards the knife clamp (2) so as to generate a compression stress in the free section of a front surface (16) of the knife (1).

Abstract: A two-stage procedure is disclosed for sorting wood chips. The chips are directed to a gyratory screen in the first stage and to a disc screen in the second stage. The chip flow is divided in the first stage into four fractions of which the first fraction contains mainly oversized chips and is directed to a pin chipper, from which it emerges as suitable-sized chips and is directed back to the gyratory screen of the first stage. The second fraction contains acceptable sized chips and most of the overthick chips and is directed to the second or thickness screening stage. The third fraction consists mainly of acceptable chips and is directed to a pulping process, while the fourth fraction consists mainly of fine particles and is directed to a burning station.

Abstract: A disk chipper for the production of wood chips, consisting of a rotatable chipping disk supported on an axle driven by at least one drive machine. The disk chipper of the invention is so implemented that at least three motors are drivably coupled to the axle of the chipping disk by means of a gear assembly, preferably a spur gear assembly.