Glue applicator for applying an adhesive to the spine or adjacent areas of a book block being conducted past the glue applicator in a transport direction

A glue applicator for applying an adhesive to the spine of a book block or to adjacent areas of a book block of stacked printed sheets being conducted past the glue applicator, the glue applicator comprising a tank holding liquid adhesive, into which at least one glue applicator roll dips to take up the adhesive and to transfer it to the spine of the book block, the roll being driven in the same travel direction as the book block, wherein the glue applicator roll interacts with a doctor blade installed above a surface of the glue in the tank so as to determine the thickness of the adhesive film to be transferred to the spine of the book block through variation of a distance of the doctor blade from the glue applicator roll and for adjustment purposes is connected to an actuating element driven by a motorized shaft, wherein the actuating element is positively connected to a cam disk, which is driven by a motor, the actuating element having a first guide roll and a second guide roll, wherein the first guide roll rests against a first radial cam of the cam disk and the second guide roll rests against a second radial cam of the cam disk having a complementary action.