Abstract: The present invention provides a self cleaning doctor blade which is a floating blade containing beveled edges or "relief gaps" comprising beveled mitered leading edges on each blade. This arrangement allows for the blades as a whole to remain free from build-up of fine particulate matter. The invention further provides a doctor blade made of replaceable units allowing for fine adjustment of blade-to-drum surface distance as well as replacement of small damaged segments rather than the whole blade.

Abstract: A method and apparatus for improving the operation of a vacuum drum filter. A hollow and perforated shower roll is located at the top of a vacuum drum apparatus for drying and cleaning paper pulp. The interior of the shower roll is provided with a liquid distribution pipe having a plurality of spaced openings therealong, the pipe also having a substantially vertically extending dam which extends radially to adjacent the lower interior surface of the shower roll. In operation, rotation of the vacuum drum in a vat of paper pulp to be dewatered results in the continuous formation of layer of pulp on its exterior surface, the layer being compressed by the shower roll at the nip between the vacuum roll and the shower roll. Concurrently, the shower roll discharges or exudes water onto and into the pulp layer at the nip.

Abstract: A method and apparatus for doctoring (cutting) the solids off a precoat filter. A stationary doctor blade continuously doctors mud (from a mud bath) from the surface of a rotating porous surface vacuum drum. A traveling doctor blade, located upstream of the stationary doctor blade, moves back and forth along the drum. The stationary blade extends the width of the rotating vacuum drum while the traveling blade is shorter and is also located nearer to the drum surface.