by the stop 132 the two stops 133 and 134 are adjustable via the knurled nut 135 and the rod 136 moreover the stop 134 is movable in anticlockwise direction by a motion of the sheet metal 130 this is indicated by the connection 137 in the position shown the toothed segment 2 rests on the stop 133 the stop 134 in contrast thereto is not effective for the toothed segment because it is tilted away from the path of the toothed segment 2 therefore the toothed segment can also be moved in anticlockwise direction thereby the window would be opened the sliding clutch and the stop 132 thereby prevent a turn of the sheet metal 130 if however the pinion is rotated in direction of arrow f in the position shown thereby a motion of the sheet metal 130 to the right against the force of the sliding clutch is effected because the toothed segment 2 is blocked by the stop 133 the rod 139 is displaced to the right and the door is locked simultaneously the stop 134 is swivelled so that the toothed segment 2 is blocked too against a rotation in anti clockwise direction when the direction of rotation of the motor 7 is reversed said motor returns to its initial position so that the door is unlocked again at the end of the unlocking operation the stop 134.