Abstract: A pin closure nozzle for injection molding molds has several working pistons acting on the same closure pin. These working pistons are arranged on a common throughgoing piston rod. Each piston rides in its own chamber and the piston rod passes through and is slidingly guided in openings in the chamber floors. The piston rod thus has at least two sliding guides and is accordingly prevented from tilting.

Abstract: A stack molding apparatus wherein the injection nozzles are disposed in pairs of coaxial nozzles in a housing between two sets of injection molds. The reciprocable valving elements of the injection nozzles of each pair are coaxial with each other and are connected with pistons which are reciprocable by compressed air. The pistons are mounted in cylinders of discrete melt supplying members which receive melt from an additional melt supplying member. The housing has two mirror symmetrical sections which can be parted in a plane between pairs of coaxial pistons to afford access to the melt supplying members, to the pistons, to the nozzles and to a device which serves to supply compressed air for reciprocation of the pistons.