Closure assembly for spanning a wall opening

A closure assembly comprising:

• a rectangular outer frame having elongated and horizontally disposed top and bottom frame members, and opposite vertically disposed lateral members that interconnect said top and bottom frame members, said top and bottom frame members having confronting rail mounting surfaces, each of said rail mounting surfaces being formed with a slide groove unit;
• at least two rectangular panel members disposed vertically within said outer frame, each of said panel members having an upper edge portion and a lower edge portion;
• at least two slidable rail units, each of which includes an upper rail disposed between said top frame member of said outer frame and said upper edge portion of a respective one of said panel members, and a lower rail disposed between said bottom frame member of said outer frame and said lower edge portion of the respective one of said panel members, each of said upper and lower rails being provided with a rolling ball unit which extends slidingly into said slide groove unit in a respective one of said top and bottom frame members of said outer frame;
• at least two pivot linking units, each of which connects said upper and lower rails of a respective one of said slidable rail units to adjacent ones of said upper and lower edge portions of a respective one of said panel members such that said panel members are pivotable relative to said upper and lower rails of the respective one of said slidable rail units about vertical axes;
• and
• at least two locking members, each of which is mounted on a respective one of said slidable rail units, and is operable to lock selectively the respective one of said slidable rail units
• to the respective one of said panel members, thereby preventing pivoting movement of the respective one of said panel members relative to the respective one of said slidable rail units while permitting sliding movement of the respective one of said slidable rail units along said slide groove units in said top and bottom frame members of said outer frame, and
• to said outer frame, thereby permitting pivoting movement of the respective one of said panel members relative to the respective one of said slidable rail units while preventing sliding movement of the respective one of said slidable rail units along said slide groove units in said top and bottom frame members of said outer frame.