Grooved spacer for disc screen wood chip sorter

A disc screen apparatus for sorting wood pulp chips by size said apparatus including a plurality of parallel shafts, each shaft being rotatable and carrying a plurality of uniformly spaced parallel discs, each of said discs having teeth disposed about its periphery, each tooth having a radially outermost portion including a tip, a portion of the periphery of any one of said discs on one of said shafts being sandwiched by side portions of a corresponding pair of the discs of a next adjacent shaft, and the sandwiched discs being spaced so as to define the maximum size of wood chips which are to pass through said disc screen apparatus, there being a minimum radial clearance between the tips of the teeth of any disc and a corresponding next adjacent shaft, each said tip following a circular path, said path including a location where the tips approach an adjacent shaft to define said minimum radial clearance, there being a lateral clearance between a radially outermost side surface portion of the teeth of any disc and the side portions of two corresponding discs which sandwich it, said lateral clearance being equal to the spacing between said sandwiched discs, and means at the locations where the tips of said teeth of any disc approach an adjacent shaft for substantially diminishing the lateral clearance between the radially outermost side surface portions of the teeth and the side portions of the discs which sandwich them, by substantially filling the lateral clearance therebetween, whereby said means effectively prevents larger than desired wood chips from being compressed by the teeth and being forced through said radial clearance.