US Patent 9995071 System and method for inhibiting window sash drift

A system and method for inhibiting inadvertent movement of a window sash out of a fully open position. Brake shoes travel in the guide tracks as the window sash is moved between a fully open position and a fully closed position. A stop is mounted within the guide tracks. The brake shoe and the stop contact and interconnect when the window sash is moved to its fully open position. The brake shoe is separable from the stop when a closing force is manually applied to the window sash that acts to move the window sash away from its fully open position. The force applied must exceed a threshold level. In this manner, the window sash will remain in its fully open position and will not inadvertently drift closed due to gravity, vibrations or contact with another window sash.