Abstract: Only the topmost sheet (12) of a stack is fed from a supply box (10) by transportation rolls (16) by way of a separating arrangement (18) to a pair of transportation rolls (20, 22). This pair transports the sheet further until the ray of a light (66) is interrupted and as a result the coupling (26) is uncoupled. As soon as the platen (32) driven by a line stepped motor (30) assumes a starting position, the coupling (26) is again engaged. The peripheral speeds of the rolls (20, 22) and of the platen (32) corresponds to one another so that the platen (32) together with a contact pressure roll may accept the sheet. After lettering, the sheet is transported by the pair of rolls (34, 36) into a file box. The pair of transportation rolls (20, 22) as well as the transportation rolls (16) are driven via a belt (50, 54) by platen drive (30).