Perfect binder

Abstract

A perfect binder wherein a horizontal table defines an endless oval track for a series of articulately connected tongs each of which has a fixed jaw and a pivotable jaw. The pivotable jaws are articulately connected to discrete levers each of which is pivotable between a first end position in which the work-engaging portions of the jaws cooperate to clamp a stack of sheets between them, and a second end position in which the work-engaging portion of the pivotable jaw is remote from the work-engaging portion of the fixed jaw. Coil springs are provided to urge the levers to either of their end positions. A first fixed cam is provided along the track to pivot the levers to their operative positions before the freshly inserted stacks reach the first treating station, and a second cam is provided adjacent a further portion of the track to pivot the levers to the other end positions in which the treated stacks of sheets can be released or withdrawn. The pivotable jaws of the tongs are mounted on the respective frames for pivotal movement about horizontal axes which are parallel to straight stretches of the endless track. The book-engaging portions are disposed at the lower ends of the jaws.