Abstract: A printing assembly which is adapted for printing on a print medium in a m of a sheet or tape includes a printing cylinder on which is wound and urged the print medium during a printing operation. A printing device prints on the print medium and urges it against the printing cylinder. An advancing device upstream of the printing device serves to advance the print medium and a tensioning device downstream of the printing devices tightens the print medium against the printing cylinder. The tensioning device includes two contra-rotating rollers having substantially smooth outer surfaces in contact from opposite sides of the print medium which allow sliding at the contacting surfaces and which provide for tensioning of the print medium on the print cylinder. The rollers are of the same diameter and are both motorpowered and driven at the same rotational velocity, which rotational velocity is greater than the advance velocity of the advancing device.

Abstract: A device for rotating at will, step by step, a shaft (2) driven from a drive shaft to which is imparted a continuous uninterrupted rotational movement in an invariable direction, comprising means for transforming the continuous rotational movement of the drive shaft into an alternating rotational movement of an intermediate rotary member (7), disengageable coupling means (9 to 13) and a free wheel device (17), interposed between the intermediate rotary member (7) and the drive shaft (2), and means for controlling the disengageable coupling means adapted so that the driven shaft is locked in rotation with the intermediate rotary member only when this latter effects a rotational movement in the appropriate direction.