Grading device, used in manufacture of filter plugs for cigarettes

A grading device includes an assembly drum with feeding grooves, and a grading drum arranged adjacent to the assembly drum and rotating in the opposite direction from that of the assembly drum at twice the peripheral speed. The grading drum has a pair of groove arrays which have grading grooves with a pitch twice that of feeding grooves on the assembly drum. The grading grooves of adjacent arrays are shifted from each other by a half pitch. The grading device further includes a pair of fork claws for holding a pair of charcoal plugs received in the feeding groove in cooperation with the outer peripheral surface of the grading drum when the paired charcoal plugs on the assembly drum pass by the grading drum. The paired charcoal plugs are put into the corresponding grading groove while rolling on the grading drum.