Patent ID: 7677961

Claim:
A device comprised of: a first side wall and a second side wall; a back wall; a work surface; a top wall, said first side wall, said second side wall, said back wall, said work surface, and said top wall defining a work area; an access opening for providing a user access to said work area; a movable sash member, said movable sash member comprised of a first end and a second end and disposed for vertical movement across said access opening to vary an effective size thereof; a drive motor; and an anti-cocking drive mechanism mechanically coupling said drive motor to said movable sash member, wherein said anti-cocking drive mechanism is comprised of: a first forward friction wheel; a second forward friction wheel; a drive shaft connecting said first forward friction wheel to said second forward friction wheel; a first flexible coupling comprised of a first end and a second end, wherein said first flexible coupling partially wraps around each of said first forward friction wheel and a first rear friction wheel and is mechanically coupled on said first end to said first end of said movable sash member; a second flexible coupling comprised of a first end and a second end, wherein said second flexible coupling partially wraps around each of said second forward friction wheel and a second rear friction wheel and is mechanically coupled on said first end to said second end of said movable sash member; wherein said first end and said second end of said movable sash member are raised simultaneously by said drive motor; wherein said drive motor is further comprised of a first drive wheel and said anti-cocking drive mechanism is a configuration in which said first drive wheel engages said first flexible coupling for rotating said first forward friction wheel, said drive shaft, and said second forward friction wheel simultaneously; and wherein said device further includes at least one evening sprocket for creating a path for said second flexible coupling such that a length of said second flexible coupling between said second forward friction wheel and said second rear friction wheel is substantially equal to a length of said first flexible coupling between said first forward friction wheel and said first rear friction wheel.