Sliding window structure with sash guiding tracks

A sliding window structure suitable for fitting in a window opening, the window structure comprising:

• two moveable casements moveable in vertical guiding grooves of a window opening section of the window structure,
• the two moveable casements each being capable of being located entirely in either of a first or a second vertical section in the window opening section;
• a breast section arranged under the window opening section and having a cavity therein,
• a horizontal branching section having a groove arranged parallel to the first vertical section and communicating with one of the vertical guiding grooves at a branching point;
• arched crossing grooves located in a lower portion of the window opening section;
• direction changing turn-outs arranged at crossing points of the arched crossing grooves and at the branching point of the horizontal branching section,
• wherein inner walls of the cavity include casement guiding grooves which may receive the two moveable casements,
• wherein the first vertical section extends along an entire interior vertical extent of both of the window opening section and the breast section, and
• wherein the second vertical section extends along an entire exterior vertical extent of only the window opening section along an exterior side of the window structure;
• and
• a horizontal connecting section connecting the first and second vertical sections.