Abstract: A retruder having a housing with a pair of counter-rotating worm gears axially mounted within said housing for counter-rotation to process a medium. The housing has an inlet and also an outlet through which the processed medium is discharged which is transverse to (radially of) the housing axis. An insert in the housing is selectively slidably movable along the housing axis to overlie the outlet to adjust its size.

Abstract: A retruder (reverse extruder) (1) having at least one housing, with charging (10) and removal (11) ports, and at least two mutually meshing reversible screws (2, 3) running in opposite directions (12, 13) and conveying the medium at the same time in the direction (14) of conveying and in the reverse direction (15). The reversal of thrust reduces the axial bearing load ont he reversible screws (2, 3) and the pressure on the bearing seals. This makes it possible to increase the conveying pressure and to increase the frictional forces of such machines without reducing the service life and the availability thereof.