Hydraulically-actuated mandrel for a demountable printing cylinder

Claim 1

The combination of a mandrel assembly and a standard printing cylinder supported thereby in a printing machine having bearings, said cylinder having annular heads fitted therein at each end said heads projecting radially inward from the inner surface of the cylinder, each head being provided with a circular bore, said cylinder, being demountable on said assembly, said assembly comprising: A. a tube receivable within said cylinder; B. respective journals joined to opposing ends of the tube and extending axially therefrom for insertion in said machine bearings, a respective journal having an expansible metal sleeve pinned thereon whose normal dimensions are such that the respective said sleeve fits into the bore of a respective end head of the cylinder, each said sleeve surrounding an annular hydraulic chamber formed on each of said journal, said chamber communicating through an internal duct filled with hydraulic fluid to a lateral bore in each said journal adjacent one end of said tube, each journal having a leading section which is shrunk fit into an end of said tube and an intermediate section which is surrounded by said sleeve and is relieved to define said annular hydraulic chamber; and C. a piston received in each said lateral bore whose foot is engaged by a piston screw and whose face subjects said fluid to pressure, whereby when said screw is turned in, the resultant pressure is transmitted by the fluid to the respective said sleeve to effect expansion thereof, causing the respective said sleeve to grip said end head.