end surfaces 38 of the tensioning bar 33 the bearing brackets 36 are arranged at the ends of the cylinder groove 5 and are prevented from slipping out of the groove 5 by two discs 41 42 each of which is secured in the area of hooking edges 10 10 1 on the plate cylinder body 1 by fastening screws 48 44 the discs 41 42 protrude somewhat into the cylinder groove 5 and each grips into a triangular slot 46 47 in the upper side of the bearing brackets 36 the tensioning bar 33 has in its upper portion two triangular recesses 49 51 which are symmetrical with each side and into which the bent over rear edge 8 of the printing plate 9 is put in the upper face 52 of the tensioning bar 33 a bore hole is provided which serves to accommodate a lever bolt 54 that is insertable into the borehole 53 through a hole in the printing plate end below the cylinder bolts 84 a longitudinal slot 56 is machined into the tensioning bar 33 this slot 56 extends along the whole length of the tensioning bar 33 and reduces the spring rigidity of lower part 57 of bar 33 in a foot section 55 of the tensioning bar 33 several transverse boreholes 68 are provided at distances distributed over the length of the tensioning bar 33 and in which bar magnets 59 are secured these bar magnets 59 protrude with both their poles 61 62 beyond the width of the tensioning bar 33 the ends of the bar magnets 59 are ground off in the area of their poles 61.