Variable size folder cylinder

A clutch assembly in combination with a folder cylinder of a folder for use in a web-fed rotary printing machine the folder cylinder having an inner pair of supporting wheels and an outer pair of supporting wheels, said inner and outer pairs of supporting wheels being axially spaced from each other on an axial support shaft and being capable of being rotatably displaced with respect to each other about said axial support shaft to permit variations in the spacing of devices carried by said inner and outer supporting wheels at the periphery of the folder cylinder, said clutch assembly being positioned between and acting on said outer and inner supporting wheels, said clutch assembly comprising:

• An axially displaceable ring shaped piston positioned in a recess in a face portion of at least one of the inner supporting wheels;
• a coupling ring secured on said ring shaped piston;
• a return membrane ring clamped between said ring-shaped piston and said coupling ring, said return membrane ring projecting over said recess in said face portion of said inner supporting wheel, said return membrane ring having an outer rim and an inner rim to seal said recess for said ring-shaped piston, said outer rim and said inner rim of said return membrane ring being secured to said face of said inner supporting wheel;
• a plurality of guide holes formed in said recess for said ring-shaped piston;
• a plurality of guide bolts on a side of said ring-shaped piston facing said recess for said ring-shaped piston, said guide bolts engaging said guide holes;
• means for supplying a pressurized fluid to said recess for said ring shaped piston;
• and
• a thrust collar carried by said outer supporting wheel and co-acting with said coupling ring whereby application of fluid pressure causes said coupling ring to engage said thrust collar to join said outer and inner supporting wheels together.