Floor panels which are provided with a mechanical locking system including tongue and grooves provided with protrusions and cavities which are displaceable in relation to each other. A set of floor panel provided with a locking system including a displaceable tongue in a displacement groove in a first edge of a first floor panel, cooperating for vertical locking of the edges with a tongue groove in adjacent second edges of a second floor panel, the locking system further including a locking strip with a locking element in one edge which cooperates, for horizontal locking of the edges, with a locking groove in an adjacent edge, the displaceable tongue includes a protrusion and the displacement groove a cavity, the protrusion is slideable against a wall of the cavity to obtain a displacement of the tongue in a first direction perpendicular to the edges and thereby the vertical locking of the edges.