provided with a vertical locking systems on short edges including a displaceable tongue that is displaced in one direction into a tongue groove during vertical displacement of two panels application_number US 201213585179 A description to facilitate understanding several locking systems in the figures are shown schematically it should be emphasised that improved or different functions may be achieved using combinations of the embodiments all embodiments may be used separately or in combinations angles dimensions rounded parts spaces between surfaces etc are only examples that may be adjusted within the basic principles of the disclosure fig2 a 2 e show a first preferred embodiment of a short edge locking system provided with a flexible and displaceable tongue 30 in an edge of a first panel 1 inserted in a horizontally extending displacement groove 40 the displaceable tongue 30 has a pulling extension 31 comprising a tongue pulling surface 32 and tongue locking surface 33 the second adjacent panel 1 u2032 has a pulling protrusion 21 with a groove pulling surface 22 that is also a part of a tongue groove 20 comprising a groove locking surface 23 the pulling surfaces 22 32 cooperate during the vertical displacement and pull the displaceable tongue 30 into a tongue groove 20 the pulling extension comprises a.