arrow direction of the arrow 14 which causes the belt buckle 1 to move counter to the arrow direction 15 the tightening process of the belt buckle 1 is then reversible in addition the spindle 11 is provided with a blocking device which prevents it from rotating back counter to the direction of the arrow 14 blocking devices of this type are also known as such and therefore are not explained further 0030 fig2 schematically shows a belt device with a belt buckle tightener according to an alternative refinement of the invention the belt buckle 1 is connected here to a fastening fitting 3 whose end which faces away from the belt buckle 1 is mounted displaceably by means of a guide pin 4 in a slot 5 of a securing plate 6 that end of the securing plate 6 which faces away from the belt buckle 1 is fastened to the vehicle chassis in this case too the belt buckle tightener comprises a winding up device 10 which is secured on the vehicle chassis and has a spindle 11 for the rolling up of a draw in cable 12 which is fastened at one end to the spindle 11 and at the other end to the fastening fitting 3 between the fastening fitting 3 and the spindle 11 the draw in cable 12 runs around a deflection pulley 13 u2032 at that end of the securing plate 6 which is opposite the belt buckle 1 the function corresponds to that of the belt buckle tightener from fig1 in an accident the spindle 11 is caused to rotate so that the draw in cable 12 is rolled up and the belt buckle 1 is displaced towards the securing of the securing plate 6.