Abstract: “A friction ring for friction shafts, particularly for winding spools, comprising an inner ring, which can be arranged on a friction shaft and is associated with an outer ring, from which means protrude for detachably locking the core of a winding spool that can be mated to the friction shaft, means being further provided for activating the locking means by mutual rotation between the inner ring and the outer ring, elastic means being provided which act between the inner ring and the outer ring to push the locking means radially outward.

Abstract: A stiffening structure for tubular shafts of light alloy, rigid plastic or similar materials, usable for rotatably supporting rolls of paper, fabric, metal strip or the like, including a plurality of rectilinear cylindrical steel bars provided with a thread and inserted, by screwing, into correspondingly threaded longitudinal holes provided in possibly angularly equidistant positions within the annular thickness of a tubular shaft of light alloy, particularly aluminium alloy, rigid plastic or a like material. The threaded holes are parallel to each other and located as far as possible from the longitudinal neutral axis of the tubular assembly, so as to enable the cylindrical bars, when screwed into the holes, to oppose the tendency of the shaft to bend during its rotation under load.