Safety device on the feed drum for monitoring the double-sheet monitoring apparatus

摘要

The invention relates to a safety device on the feed drum for monitoring the double-sheet monitoring apparatus on sheet-fed printing machines. The aim of the invention is to provide a safety device with which, in the event of unnoticed failure of the double-sheet monitoring apparatus, the feeding of double or multiple sheets into the printing machine is prevented and machine damage is thus avoided. The object of the invention is to develop a safety device with which the sheet transport on the feed drum is monitored for double or multiple sheets and the setting thereof is coupled to particular paper thickness with the top-lay setting. According to the invention this is achieved in that, to a known linkage mechanism for setting the gap between the top lay and feed table, there is coupled a second linkage mechanism which executes virtually the same regulating paths as the first linkage mechanism and whose final link, designed as an angle lever, is provided with a limit switch which interacts with the grippers of the feed drum and is disposed in the main circuit. The first linkage mechanism and the second linkage mechanism are designed such that, with central setting by the regulating spindle, the distance change of the top lay and of the limit switch are the same. <IMAGE>