Silent overload protection for extruder screw - has gearwheel transmission balls which roll silently in disengaging groove when screw is overloaded

摘要

In the parent specification a screw extruder has a protective device for the screw in the form of a gearwheel in its drive acting as an overload coupling. The gearwheel rim rotates on its hub and has spring-loaded balls which move into slots in one side of the hub but engage in seating holes until they are moved by a particular torque relative to the hub. In this addn. the one side of the gearwheel has a groove radially inside or outside the holes which hold the balls. The slots which receive the balls are open to that groove at an acute angle so that the balls can be forced from their seating holes into the groove. The parent design permits the balls to move into adjacent slots which generates considerable noise and risks of damage. The new design eliminates both problems.