heat sealing head 14 to press the bag stock 20 to the seal roll 16 to effect a heat seal 36 across the width of the bag stock 20 and intermittently along the length of the bag stock 20 and upwardly to allow the bag stock to be moved by the roller 30 32 along the direction x the heat seals 36 close lateral edges of individual bags 37 which are separated by the action of the heat seal head 14 from the bag stock 20 thus each bag 37 is closed on three sides by a lengthwise fold of the bag stock 20 not shown and two heat seals 36 a rotating wicketer 38 receives the bags 37 successively from the heat seal region 22 on revolving arms 39 which hold the bags 37 by vacuum and deliver the bags 37 to a further station or conveyor not shown a rocker 40 is provided pivoted about a center axis 42 the rocker 40 in fig1 is shaped in the form of a segment of a circle the rocker 40 pivots about a pivot connection 44 to a pneumatic linear positioner 45 including an air cylinder actuator 46 the actuator includes an extendable shaft 48 connected to a round lug 50 at the pivot connection 44 the actuator 46 is pin connected at a top lug 52 to stationary support structure 56 at an opposite end of the rocker 40 from the pivot connection 44 is a brake roller 58 pinned to the rocker 40 a drive pulley 60 is mounted flushly to the rocker 40 and having the same axis of rotation 42 mounted at an axial end of the seal roll 16 is a driven roll.