Flush lock for casement window and method of operating the same

A method of securing a window sash to a casement window frame, said method comprising:

• actuating a flush lock for said casement window, wherein said casement window includes an elongated casing having a substantially horizontal sidewall section and a vertical section shorter in length than said sidewall section, and said flush lock includes:
• a fork component adapted to engage a lock bar external to said lock, said fork component in slidable communication with said casing;
• a lifter in slidable communication with said fork component;
• a restrictor arm pivotally attached to said casing;
• a plurality of hinges or pivot points forming an over center linkage to prevent back driving said lock, wherein said over center linkage includes:
• a first hinge point rotatably joining said handle to said lifter;
• a second hinge point rotatably joining said handle to said restrictor arm;
• a third hinge point rotatably joining said restrictor arm to said casing;
• said handle pivotally attached at one end to said lifter, and pivotally attached at an intermediate point on said handle to said restrictor arm;
• rotating said handle to engage said lifter to an unlocked position, such that said first hinge point is between said second and third hinge points, and said second hinge point is below an action line connecting said first and third hinge points;
• or
• rotating said handle to engage said lifter to said locked position, such that said second hinge point is between said first and third hinge points, and said second hinge point is below an action line connecting said first and third hinge points;
• moving said fork component horizontally along said casing horizontal sidewall section;
• and
• simultaneously lifting or lowering said lifter relative to said fork component.

A casement window lock for securing a window sash to a casement window frame, said lock comprising:

• a casing having an elongated horizontal sidewall with a shorter vertical dimension, said casing including elongated side members, and tracks on at least one side member extending along an inside surface thereof, said tracks including a first track substantially horizontal and extending along said casing elongated horizontal sidewall, and a second track having at least one angled portion extending vertically relative to said first track's horizontal position;
• a restrictor arm pivotally attached at one end to said casing, and pivotally attached at the other end to a handle;
• a fork component including:
• an attachment portion for engaging a lock bar;
• an attachment for slidably retaining a lifter;
• a protrusion for slidably engaging said first track;
• and
• said lifter in slidable contact with said fork, including:
• an extending protrusion for slidably engaging said second track;
• an attachment for pivotally connecting said lifter to said handle;
• said handle in pivotal communication with said restrictor arm at one end of said handle, and in pivotal communication with said lifter at an intermediate point on said handle;
• and
• wherein, when said handle is rotated to unlock said lock, said handle pivots about said lifter and said restrictor arm, respectively, causing said fork component to traverse horizontally in a first direction about said first track while simultaneously causing said lifter to shift vertically as said lifter traverses said second track, and when said handle is rotated to lock said lock, said handle pivots about said lifter and said restrictor arm, respectively, causing said fork component to traverse horizontally in a second direction opposite said first direction about said first track while simultaneously causing said lifter to shift vertically as said lifter traverses back on said second track.