the web 2 to imprint web sectors whose length corresponds to the circumferential extension of the blanket rollers 10 and 11 the springs 22 and 23 are selected in order to obtain in a very short time after the buckling of the toggle lever means 16 17 movements of the offset cylinders 10 and 11 to the printing position in which conventional abutment rings of offset cylinders 10 and 11 engage each other for obtaining imprinting of the web by the offset rollers 10 and 11 during the time period in which the printing rollers 10 and 11 are to be spaced and inoperative the eccentric member 24 holds the toggle levers 16 and 17 in the aligned position due to the connection by rod 19 with the toggle joint 18 evidently a modification is possible in which the springs urge the shafts of the printing rollers 10 and 11 apart and in which the operating means 19 20 21 24 effects folding of the toggle levers 16 and 17 for movement of the printing rollers 10 and 11 to the printing position printing cylinders 10 and 11 have shafts not shown which are mounted in eccentric bushings within the arm means 12 and 13 so that the usual operations for separating offset blanket rollers 10 and 11 from the platen rollers 14 to 15 can be carried out the number of revolutions of the eccentric member.