An apparatus for effecting closure of an open end of a carton blank by placing portions of the carton blank into overlying relationship to one another is provided. The apparatus includes a cam that rotates about an axis of rotation and a cam lever that is operatively connected to the cam. The cam lever is used to convert rotating motion of the cam into linear motion to define a first stroke distance. A pressure pad is mounted for movement toward and away from the portions of the carton blank. The pressure pad is capable of being moved in response to input provided by the cam to define a second stroke distance. An air spring is mechanically linked to the cam lever and the pressure pad such that the air spring absorbs a portion of the first stroke distance.