Tilt window assembly

Claim 1

IN A WINDOW ASSEMBLY, AN UPPER AND A LOWER SASH EACH HAVING A PAIR OF VERTICALLY EXTENDING SIDE RAILS, SAID LOWER SASH BEING WIDER THAN SAID UPPPER SASH, A PAIR OF VERTICALLY EXTENDING SIDE STILES HAVING LATERALLY INWARDLY OPEN CHANNEL PORTIONS AND AN AXIALLY OUTER STOP PORTION THEREIN, A PLASTIC TRACK HAVING A PAIR OF PARALLEL LATERALLY OUTWARDLY EXTENDING RIBS THEREON TO PROVIDE A PAIR OF RECESSES ON THE LATERALLY INNER SURFACES OF SAID PLASTIC TRACK RECEIVED IN EACH OF SAID SIDE STILES IN THE CHANNEL PORTION THEREOF, THE AXIALLY INNER OF SAID RECESSES IN EACH OF SAID TRACKS BEING LATERALLY OUTWEARDLY OFFSET FROM THE OTHER OF SAID RECESSES IN THE SAME TRACK AND CONNECTING THERETO BY A LATERALLY INWARDLY EXTENDING SECTION, COMPRESSIBLE MEANS POSITIONED IN SAID CHANNEL PORTIONS AND URGING SAID PLASTIC TRACKS LATERALLY INWARDLY TO ENGAGE SAID SIDE STILES, SAID PLASTIC TRACKS RECEIVING SAID SASHES THEREON FOR CONTROLLED SLIDING MOVEMENT, SAID PLASTIC TRACKS HAVING LATERALLY NARROW AXIALLY OUTWARDLY FACING SHOULDERS ABOUT 1/16" LONG AT THE AXIALLY INNER MARGIN OF EACH OF SAID RECESSES TO ENGAGE A CORNER OF SAID SASH RAILS AND AID IN FORMING A SEALED SLIDABLE CONNECTION THEREWITH SAID PLASTIC TRACK HAVING FLAT SURFACES THEREON IMMEDIATELY ADJACENT BOTH EDGES OF SAID RECESSES, SAID SIDE RAILS OF SAID SASHES HAVING FLAT LATERALLY OUTER SURFACES ENGAGING SAID FLAT SURFACES OF SAID PLASTIC TRACK TO AID IN POSITIONING SAID SASHES, SAID SECTIONS OF SAID TRACKS FORMING A STOP FOR SAID LOWER SASH TO RETAIN IT AGAINST AXIAL OUTWARD MOVEMENT, SAID STOPS OF SID SIDE STILES FORMING STOPS FOR SAID UPPER SASH TO PREVENT AXIAL OUTWARD MOVEMENT THEREOF, SAID PLASTIC TRACKS BEING MOVABLE LATERALLY OUTWARDLY TO COMPRESS SAID COMPRESSIBLE MEANS AND PERMIT REMOVAL OF SAID SASHES FROM THE AXIALLY INNER PORTION OF THE WINDOW ASSEMBLY.