Abstract: To fold sheets of newsprint (1), a ring gear 7 is driven in rotation by a motor 11 under the control of a controller 12 such that, for most of the time, the ring gear 7 rotates at the same speed as a folding cylinder 2 and arms 8. When it is desired to initiate a folding operation, the ring gear 7 is momentarily stopped or slowed. The relative motion that occurs between the ring gear 7 and planet gears on the arms 8 causes the planet gears 9 to rotate about their axes and respective tucking blades 6 mounted on the planet gears 9 to protrude above the surface of the cylinder 2, where they engage collated sheets on the cylinder surface and push them into the nip of folding rollers (4). Upon completion of the movement of the planet gears 9 and associated tucking blades 6, the ring gear 7 is again caused to move at the same angular speed as the arms 8, such that the tucking blades 6 retain their “silenced” positions below the surface of the cylinder 2.