Paper trimming machine and control system therefor

摘要

917,339. Electric correspondence control systems. SMITH & WINCHESTER MANUFACTURING CO. Aug. 3, 1961 [Jan. 17, 1961], No. 28256/61. Class 40 (1). Apparatus for trimming sheets of paper to a required length comprises an automaticallybalanced resistance bridge consisting of a manually-adjusted potentiometer 73-76, and a circular potentiometer 40 carried on a lead screw for the back gauge of the trimmer, movable along a rail relative to a fixed cutting knife. The rebalancing motor is selectively coupled to the lead screw through clutches to provide a fast or slow forward movement, but only a fast reverse movement, whereby the back gauge always overshoots in the reverse direction and comes to rest in the forward direction at slow speed, thus overcoming backlash errors.