A stop assembly comprising a generally cylindrical body whose outer surface is adapted for engaging the interior cylindrical surface of a hollow core, a plurality of fingers secured to the body for pivotal movement about axes generally parallel to that of the core between first positions in which the fingers lie radially within the outer surface of the body and second positions in which the fingers project beyond the outer surface for engaging an end surface of the core, each of the fingers having a core engagement surface lying in a plane generally perpendicular to the outer surface of the body and adapted for engaging the core end surface and a generally oppositely-facing camming surface inclined relative to the core engagement surface, the fingers being biased outwardly and no fixed portion of the assembly lying radially outwardly of the outer surface so that the entire assembly may be inserted into and through a core having an interior cylindrical surface of diameter not substantially greater than that of the diameter of the outer surface.

In a photographic printer, photographic print paper is transported from the print paper supply to a print mask location. The print paper is guided by an interchangeable guide spool to ensure proper centering at the print mask location. The guide spool, being preset for a particular print paper width, automatically centers the print paper when mounted on a spindle so as to abut against a permanently positioned flange. The guide spool includes an inner sleeve that abuts against the permanently positioned flange, an outer sleeve coaxially rotating around the outer surface of the inner sleeve and having an outer surface that engages the photographic print paper, and guides attached proximate both ends of the outer sleeve for guiding the print paper on the outer surface of the outer sleeve.

A core chuck designed to lock the core of a roll of material winding and unwinding operations to a mandrel, which core chuck comprises a core and a tubiform cylindrical chuck body dimensioned to accommodate the core. Means are provided for fastening the chuck body onto the mandrel shaft. The chuck body defines on the surface opposite the core at least one recess disposed parallel to the rotating axis thereof which recess has a releasably terraced bottom step plate including at least one step ascending from a common center groove to each side of the recess. The top faces of the step and of the common center groove are substantially parallel to and spaced apart at different distances from the opposite smooth face of the core. At least one toothed roller is disposed in the recess with its axis parallel to the axis of the chuck body. The top face of each of the steps has two raised ribs spaced apart from each other to define an axially disposed groove therebetween, and receives the corresponding tooth of the toothed roller, in order to prevent an axial movement and an inclined position of the latter. Retaining means are provided to prevent the overextension of the springs, as well as the outward movement of the locking roller and of the step plate. The retaining means may include an arch shaped stamping which is inserted with slight pressure at each end of the roller recess, to form a cover or roof, both legs of the arch shaped stamping resting on the top side of the step plate. The toothed roller has an extended pin on each end and said extended pin is disposed spaced apart from the bottom face of said stamping upon locking the same in said core.

A device for releasably holding a core or the like relative to a drive shaft passing therethrough includes at least two clamping elements located within the core. Guide pieces are fixed to a ring disc which surrounds a ring connected to the drive shaft. These guide pieces allow the clamping elements to move radially relative to the drive shaft and hold the core. A friction brake is provided to brake the ring relative to the ring disc. Also, a locking pawl arrangement is provided to selectively prevent the ring disc from rotating with the drive shaft. Accordingly, back slipping is prevented which undesirably loosens the core from the clamping elements.

A device for chucking tubular winding cores, and particularly cores carrying paper webs or webs of similar material, wherein chucking segments forming a cylindrical surfaces are radially positioned by means of a core trunnion having an equilateral polygonal cross section, each of the chucking segments bearing on an individual surface of the trunnion through a support member having a rounded profile and producing a line contact. The support members are carried without play or with very little play in a cage inserted coaxially to be freely rotatable between the chucking segments and the core trunnion.