Sliding window lock

A lock assembly for a horizontal sliding sashless window assembly having a frame including a lower horizontal sill with said frame defining a window opening;

• a fixed sashless pane disposed within said frame and covering a portion of said window opening and a sliding sashless pane received within said frame and slideable on said sill between a closed position with said sliding pane covering an exposed portion of said opening not covered by said fixed pane and said sliding pane horizontally slideable to an open position to open said exposed portion;
• said fixed and sliding pane disposed within said frame and sized such that said sliding pane has a portion thereof overlapping said fixed pane when in said closed position and terminating at a generally vertical leading edge adjacent said fixed pane with said overlapping portion increasing in size as said sashless pane is moved to an open position;
• and with said sliding pane free for limited vertical movement within said frame;
• said lock assembly comprising:
• a block;
• pivot means for pivotally securing said block to said sill to pivot about a vertical axis disposed opposing said leading edge when said sliding pane is in a closed position and with said block pivotable between a locked position and unlocked position;
• said block shaped that when in said locked position to present a generally vertical lock surface opposing said leading edge with said vertical lock surface having a horizontal dimension substantially equal to a horizontal dimension of said leading edge;
• said block further provided with a shoulder having a blocking surface opposing a vertical surface of said sliding pane generally parallel to said direction of sliding movement;
• said lock surface spaced from said leading edge a distance to present a clearance with said lock surface free to pass through said clearance as said block is pivoted from said locked position to said unlocked position;
• anchor means for restraining said block from pivotable movement when said block is in said locked position comprising cooperating mating elements on said block and said sill with said mating elements slideably movable relative to one another in a straight vertical line between a captured position and a free position;
• said elements in said free position free to move relative to one another in a direction perpendicular to said pivotal axis and with said elements in said captured position restrained from movement relative to one another in a direction other than along said straight vertical line;
• said pivot means in said block provided with mating vertical sliding surfaces permitting vertical sliding movement of said entire block away from said sill in a direction parallel to said straight vertical line of movement of said anchor means mating elements with said pivot means mating surfaces permitting vertical movement at said pivot axis a distance that is at least as great as a stroke of said anchor means between said capture and free positions;
• stop means restraining vertical sliding movement of the block from the sill from moving more than a predetermined maximum distance;
• and
• a spring engaging said pivot means and said block for biasing said block toward the sill and resisting vertical sliding movement of said block away from said sill.