Locking mechanism for sash type windows

A locking mechanism for a window having a window frame including a guide groove extending in movement directions, and having upper and lower sashes at least one of which is slidable with respect to said frame in said movement directions, each of said sashes having a meeting rail, said meeting rails adapted to lie adjacent one another when said sashes are in a closed position, said locking mechanism comprising

• i) at least one sash clamp connected to one of said meeting rails,
• ii) at least one receiving element corresponding to said at least one sash clamp connected to the other of said meeting rails,
• iii) a pawl disposed at an end of said one of said meeting rails and adapted in an extended position to lie within said guide groove,
• iv) a handle movable between a locked position, an unlocked position and an auxiliary position, and
• v) an operating mechanism including an actuator rod responsive to movement of said handle and upon which rod said at least one sash clamp is pivotally carried such that when said handle is in said locked position said at least one sash clamp engages said at least one receiving element, and when said handle is in said unlocked position said at least one sash clamp disengages said at least one receiving element;
• wherein said pawl is spring-biased to said extended position, and said pawl and said actuator rod are provided with cooperation means such that when said handle is moved from said unlocked position to said auxiliary position said actuator rod effects retraction of said pawl from within said guide groove.