Patent ID: 7975432

Claim:
A casement window assembly comprising a main support frame for installing within a window opening of a building structure, a sash frame supported for swinging and horizontal movement on a vertical pivot axis by said main support frame between a closed position disposed within said main support frame and an open position projecting outwardly from said main support frame, an insulated glass panel unit mounted within said sash frame, a metal extrusion section comprising a metal hook member having a base portion rigidly secured to a vertical frame member of said sash frame by fasteners for movement with said sash frame to said open position and including a vertically extending T-shape tip portion integral with said base portion, said tip portion having J-shape hook portions projecting horizontally in opposite directions from said tip portion, a metal extrusion section comprising a metal hook channel having a base portion rigidly secured to a vertical frame member of said main support frame by fasteners and including horizontally spaced and vertically extending inner and outer vertical legs integral with said base portion of said channel with said legs having J-shape hook portions projecting towards one another and defining a space therebetween, said metal hook member and said metal hook channel each having a vertical height substantially less than a vertical height of said sash frame and positioned only adjacent said pivot axis, a vertically extending resilient and compressible sealing member positioned between said vertical frame member of said sash frame and said vertical frame member of said main support frame, said tip portion of said hook member passes without interference through said space between said hook portions of said hook channel when said sash frame moves on said vertical pivot axis between said closed position and said open position, and one of said J-shape hook portions of said metal hook member and a corresponding one of said J-shape hook portions of said metal hook channel interlocking with each other in response to a deflection of said vertical frame member of said sash frame relative to said main support frame when said sash frame is in said closed position.