the cradle 75 is brought into the second position shown in chain dotted lines in fig1 during the printing stage downwardly bent pairs of lugs 76 and 77 are formed on the cradle 75 to each lug there is fixed a pin 78 engaging in a curved slot 79 formed in a sub frame 80 fast with the fixed frame 1 of the machine another pair of lugs 81 is formed in the proximity of the rear edge of the cradle 75 levers 82 pivoted to the lugs 81 by means of the pins 83 are connected to a mechanism of known type not shown in the drawings for opening and closing the cradle and operating in a predetermined working cycle for example as described in copending application ser no 481 558 filed june 21 1974 the machine operates in the following manner to introduce the journal sheet 20 the rollers 24 and 27 are lifted away and the sheet 20 is made to slide along the paper guiding element 21 causing it to pass between the row of rollers 24 and the main platen 8 the two hopper elements 65 and 66 having been shifted to the right to allow access to the front zone of the crosspiece 33 the sheet 20 is bent back and is introduced between the second row of rollers 27 and the.