Abstract: Wood chipping apparatus including a removable wood chipping cartridge in the form of a hollow drum having axial extending wood chipping knives positioned adjacent to wood chip receiving apertures in the drum. The drum is removably connected, at one end, to the end of a drive shaft, whereby the drum is supported in a cantilever fashion. For knife sharpening, the entire cartridge is removed and replaced with a cartridge having sharpened knives.

Abstract: A continuous digester in which liquor is drained, at various levels, through a screen into a compartment formed by half rings attached to the interior of the digester. The compartment is provided with rotating vanes, which backwash the screen by pulsing liquid therethrough. The digester includes a lower cone, provided with an impeller and compartment for introducing and circulating liquor for "cold blow" of product.