Abstract: A platen for a typewriter, is rotated intermittently by pulsing a winding to establish flux between poles of a stator and a rotor, which rotates through a fixed angle and then back to a datum position under the action of a spring. The magnetic flux also engages an electro magnetic clutch formed by the rotor and a part rotationally fast with the platen so that the platen is rotated only during the forward rotation of the rotor. The stator, rotor and said part are all coaxial with the platen and may be housed inside the platen.

Abstract: An arrangement for transferring a ribbon from a feed spool to a take-up spool comprises a pair of electric motors each one connected to a corresponding spool for the rotation thereof. The motor connected to the take-up spool is supplied by a constant current generator so as to wind-up said ribbon with a minimum and substantially constant torque. The motor connected to the feed spool is supplied by a constant voltage generator so as to keep said ribbon constantly taut during the transferring thereof. A changeover device alternates the function of the two spools when the ribbon is fully wound on the take-up spool.