Device for automatically adjusting vertically directing and aligning means in dependence on said containers size. The directing means are formed by a plurality of cradles (5) and the aligning means are formed by a corresponding plurality of discharge channels (6), both means are provided with movable parts (10, 35), respectively, adjustable in dependence on plastic containers size. The device provides at least one control member located on the machine outer stationary cylindrical wall (3) and adapted to engage movable parts (10, 35) of cradles and discharge channels, respectively, while the inner hopper holding bulk plastic containers rotates. Movable parts (10, 35) respectively, act on a movable fin (26) that adjusts the cradle cross-section and a movable rear wall or back (33) of the discharge channel.