Patent ID: 8439203

Claim:
A vibratory screening machine, comprising: a primary screening area; and a pre-screening assembly including a frame having an elongated central keystop and screen assemblies including a first substantially horizontal screen assembly, a first substantially vertical screen assembly, a second substantially horizontal screen assembly and a second substantially vertically screen assembly, wherein the first substantially vertical and first substantially horizontal screen assemblies are pressed together and against a first surface of the keystop and releasably secured to the frame and the second substantially vertical and second substantially horizontal screen assemblies are pressed together and against a second surface of the keystop opposite the first surface of the keystop, the first substantially vertical and first substantially horizontal screen subassemblies and second substantially vertical and second substantially horizontal screen assemblies forming a concave pre-screening surface, wherein the frame is attached to the vibratory screening machine such that the concave pre-screening surface is above the primary screening area.