Patent ID: 8424454

Claim:
A printing unit for printing a web of paper comprising: a frame, the frame having a lateral wall with at least one opening therein; an upper printing group including an upper blanket cylinder, an upper plate cylinder and an upper tubular blanket for mounting on the upper blanket cylinder, the upper tubular blanket sliding on the upper blanket cylinder through the at least one opening to change the upper tubular blanket; a lower printing group including a lower blanket cylinder, a lower plate cylinder and at least one lower tubular blanket for mounting on the lower blanket cylinder, the lower tubular blanket sliding on the lower blanket cylinder through the at least one opening to change the lower tubular blanket; a printed web passing through the printing unit between the upper blanket cylinder and lower blanket cylinder; and a cylinder support and movement mechanism moving the upper printing group and lower printing group into a throw-on configuration and a plurality of throw-off configurations; the throw-on configuration occurring when the upper blanket cylinder contacts the lower blanket cylinder and the upper and lower blanket cylinders contact the upper and lower plate cylinders respectively, a first throw-off configuration occurring when the upper blanket cylinder is spaced apart from the lower blanket cylinder and the web, and the upper and lower blanket cylinders are spaced apart from the upper and lower plate cylinders respectively, a second throw-off configuration being a blanket-changing throw-off configuration occurring when the upper blanket cylinder is spaced apart from the lower blanket cylinder and the web, a distance between the upper blanket cylinder and the lower blanket cylinder being greater than a distance between the upper and lower blanket cylinders when the upper printing group and lower printing group are in the first throw-off configuration and the upper and lower blanket cylinders are spaced apart from the upper and lower plate cylinders respectively, the printed web passing through the space between the upper and lower blanket cylinders while the upper and lower printing groups are in the blanket-changing throw-off configuration.