Winding machines

A center shaft turret winder is provided with core change-over mechanism, so that rewinding of webs e.g. in a slitter-rewinder can proceed continuously, by replacing full cores with empty cores and severing the wound webs between the respective cores. The mechanism includes a knife member which pivots about an axis parallel to the center shaft axis to bring its cutting edge into contact with the moving webs, after the core shafts have rotated around the center shaft, so that the tension in the webs increases and they are severed so that rewinding continues on the new cores and the old, full cores can be removed and replaced with empty cores. A paper printing and slitting machine equipped with such a slitter/rewinder and change-over mechanism is disclosed, together with the electromagnetic clutch arrangements for driving the winding cores and various forms of knife member.