Mechanical locking system for panels and method of installing same

A set of floor panels which are mechanically connectable to each other along one pair of adjacent edges, each of said floor panels comprising:

• a flexible tongue on a first edge of the panel;
• a tongue groove on a second opposite edge of the panel for receiving the flexible tongue of an adjacent panel for mechanically locking together said adjacent edges at right angles to a principal plane of the panels thereby forming a vertical mechanical connection between the panels;
• the tongue groove is formed in a core of the panel;
• and
• a locking element formed in one piece with the panel at the first edge and a locking groove at the opposite second edge, the locking groove being open towards a rear side of the panel, the rear side of the panel being adapted to face a sub floor upon installation, the locking element being a vertical protrusion extending towards a front side of the panel, the front side of the panel being adapted to be visible upon installation;
• wherein the locking element and the locking groove form a horizontal mechanical connection for locking the panels to each other horizontally parallel to the principal plane and at right angles to the joined first and second edges;
• the flexible tongue being resilient and formed of a separate material than the core, and cooperates with the tongue groove;
• wherein the flexible tongue is spaced horizontally from the locking element;
• wherein two of the panels have structure that is adapted to be mechanically joined together by displacement of said two panels vertically towards each other, while at least a part of the flexible tongue is resiliently displaced horizontally until said adjacent edges of the two panels are brought into engagement with each other vertically and the tongue is then displaced towards its initial position against the tongue groove;
• wherein the flexible tongue has an inner part mounted in a sideward open groove in the first edge and a protruding part protruding downward towards the rear side of the panel, wherein the inner part is fixed in the sideward open groove, and wherein the part of the tongue which is resiliently displaced is the protruding part;
• wherein a bottom-most portion of the sideward open groove is vertically positioned above an upper-most portion the locking element when the first and second edges are connected together;
• wherein immediately juxtaposed upper parts of two adjacent joint edges of two joined floor panels together define a vertical plane perpendicular to the horizontal plane;
• wherein the protruding part protrudes from the inner part in the sideward open groove and beyond the vertical plane.