Safety device for guarding nips in a sheet-fed rotary printing press

Abstract

A sheet-fed rotary printing press having lower and upper blanket cylinders in running engagement with an impression cylinder to form nips accessible through an access space. The driving means for the cylinders includes an inching circuit and a drive enabling circuit. An interlock switch adjacent the access space is connected in the drive enabling circuit. A safety subassembly and a washing subassembly are provided with quickly disengageable means for mounting the subassemblies in position successively in the access space. The safety subassembly includes a guard plate having a normal position in which the plate closes off the access space and forms a sheet guide. A first disengageable linkage couples the guard plate to the interlock switch so that when the plate is in its normal position the enabling circuit is enabled for normal driving of the press and so that when the guard plate is absent from its normal position the press is limited to inching movement. A second disengageable linkage couples the washing subassembly to the interlock switch so that when the washing subassembly is in the access space in place of the safety subassembly the enabling circuit is enabled to permit normal driving of the press for washing purposes. In the preferred embodiment the guard plate is formed of two sections horizontally hinged together.