Patent ID: 7942353

Claim:
In combination with at least one of a material grinder and a hammer mill having a housing and a material destruction member operatively mounted in such housing, an adjustable screen apparatus comprising: (a) a first member which is stationary fixed adjacent such material destruction member and between opposed sides of such housing, said first member having a predetermined plurality of first openings which are disposed in a first predetermined pattern; (b) a second member positioned in an operatively juxtaposed and nesting relationship for a reciprocal movement relative to said first member, said second member having a predetermined plurality of second openings which are disposed in a second predetermined pattern; (c) a guide means for guiding said reciprocal movement of said second member relative to said first member; and (d) a power operated drive means coupled to a source of power supply and having a linearly moving member thereof attached directly to said second member for reciprocally moving said second member between a first position wherein each of said plurality of said second openings substantially overlaps a respective one of said plurality of said first openings for producing large size particles and a second position wherein said each of said plurality of said second openings partially overlaps each of a pair of adjacently disposed first openings for producing small size particles.