| 摘要 |
When the plate cylinder (D) is provided with at least one longitudinal channel (C) housing the sheet grippers (P) and when the ends of this channel have cams (Z) for contact with rollers mounted on the cleaning assembly, to ensure that when this assembly is actively working the presser (6) and cloth (T) do not interfere with the said grippers as they pass the said channel (C), the shoulders (2) of the said cleaning assembly are held stationary and the said cams (Z) of the cylinder (D) contact directly, or via interposed means, rollers (20) located at the ends of the presser (6), in such a way as to move only this component rather than the whole cleaning assembly as in the prior art. Compensating means are provided to cause the active length of cloth to remain suitably tensioned in the longitudinal direction and promptly to follow the presser's (6) movements of extension and retraction. When the end rollers of the presser are actuated by the interposition of pairs of pivoting levers (22, 25), arrangements are made to enable these pairs of levers to contact the cam (Z) located on one side only of the plate cylinder, the levers being connected to each other by at least one torsion bar (31).
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