Abstract: The mechanism allows a document of various thicknesses and indeed variable thickness to be franked. Said mechanism includes a frame (11) which supports a pressure roll (5) and a lower feed roll (4) and urged towards the chassis by means of three springs (14) so as to allow the shafts of said rolls (4) and (5) to move in any direction.

Abstract: A compact print wheel position sensing device for parallel-wheel printers includes pairs of optoelectronic printed circuit emitters 22 and receivers 24 arranged in two lines inside and outside, respectively, a tubular shaft 21 provided with radial holes 23 aligned with each emitter/receiver pair and carrying wheels 19 which mesh with corresponding parallel print wheels 11. Each wheel 19 has a set of angularly spaced transparent regions, alternating with opaque regions, which permit transmission between the corresponding emitter/receiver pair at each printing position of the respective print wheel. A logic device includes a memory arranged for storing printing wheel position orders and having double reading heads for each division.