Screw press

A screw press comprising a press body, a ram mounted for reciprocating movement relative to said body, a threaded spindle extending from said ram for transmitting movement to said ram, a nut member mounted in said press body for supporting said spindle for rotational movement about the axis of said spindle and for moving said spindle in the axial direction thereof when said spindle is rotated, a flywheel coaxially joined to said spindle for transmitting rotational movement to said spindle, and at least two friction gear units arranged about the circumference of said flywheel for rotatably driving said flywheel, each of said friction gear units including a friction disk having its axis extending substantially perpendicular to the axis of said spindle so that said disk confronts the outer periphery of said flywheel, a disk shaft extending coaxially from said disk and supported by said press body for rotational and axial movement relative to said press body, wherein said disk is movable between a first position whereat said disk contacts the outer periphery of said flywheel to transmit rotational movement to said flywheel and a second position whereat said disk is moved away from said flywheel, means for moving said friction disk toward said first position and means for moving said disk toward said second position, and a drive unit supported by said press body for rotatably driving said disk, said drive unit of one of said friction gear units including a common drive shaft and two motors which are arranged to be alternately actuated to drive said common drive shaft, one of said motors being arranged as a secondary motor and having a higher gear ratio relative to the other motor to drive said flywheel at a rotational speed sufficiently slow and in either direction to enable said ram to be moved to a given position.