also arranged always centrally in the mold parting plane as indicated in fig1 at normal operation only one gear 50 is in effective engagement by means of the respective centering cylinder 58 the centering cylinders 58 of the synchronizing guide system are operatively connected to the synchronizing device 44 with the synchronizing device 44 including e g a rack and pinion system with a right and a left rack 40 42 and 46 48 and an interposed gear 50 or pinion as schematically illustrated in fig4 one rack 40 42 and 46 48 is thereby securely fixed to one mold mounting plate 22 and 24 24 and 26 respectively both racks may certainly be arranged also above below each other through actuation of the centering cylinders the gear 50 of the synchronizing device 44 engages for example both racks 46 48 or is idle through displacement disengagement the horizontal movement and rapid closing movement rapid feed of both blow mold halves 14 16 and 18 20 is effected only by a single hydraulic driving cylinder 52 which is arranged centrally on the table 34 and is connected and coupled with the downwardly extended central platform 30 thus the driving cylinder 52 directly moves only the central platform 30.