Abstract: A track assembly for a sliding closure member comprising a track extending in a longitudinal direction. A support arm is mounted at one end in the track for travelling movement along the track by a connecting means which retains the arm generally perpendicular to the track during part of the travelling movement. The connecting means also permits rotation of the arm about an axis perpendicular to the common plane of the track and arm in one end region of the track. The connecting means comprises a ball roller mounted on the arm for rolling movement along the track when the arm is generally perpendicular to the track. The ball roller also permits rotation of the connecting means about the axis perpendicular to the common plane of the arm and the track. A holding means engages the connecting means to prevent such rotation when the connecting means is not positioned in the end region of the track.