PURPOSE: To simplify the structure of a drum by fitting a support member to a shaft on both ends of a barrel with grooves provided in circumferential direction in freely rotatable fashion, engaging a suction member mounted on a suction pipe supported between support members-with each groove and fixing the drum and support members after adjustment of their phases.

CONSTITUTION: A double diameter drum 12 consists of a drum with shafts 32, 33 at both ends supported on a shaft on the side of a frame 36. The drum 31 has a plurality of grooves 59 extending in circumferential direction on an external peripheral wall. The shafts 32, 33 on both ends are fitted with a side plate 47 in freely rotatable manner. Between these right and left side plates 47, a suction air pipe 48 connected to a suction air source through a rotary valve 55 is supported, and over this suction air pipe 48, a plurality of suction air heads 59 connected continuously to the inner hole of the suction air pipe are fixed in parallel and engaged with each groove 59. Then the drum 31 and the side plate 47 are phase-adjusted in accordance with one side and both side printings and paper size, and fastened with nuts 74. Thus the 31 and the side plate 47 are strongly fixed with a surface pressure created by a keep plate 69b on both sides.