Method of and apparatus for transporting and turning stacks of paper sheets

A method of turning stacks of paper sheets or the like, comprising the steps of establishing parallel elongated first and second paths, said first path being defined by a first conveyor means and said second path being defined by a plurality of independently controlled second conveyor means;

• delivering successive stacks into first portions of the paths in a predetermined starting orientation so that a first part of each stack overlies the first path while a second part of the stack simultaneously overlies the second path;
• advancing the first and second parts of successive stacks from the first portions of the respective paths in the same direction but at different speeds so that the stacks are turned as a result of the difference in speeds of their first and second parts and their orientation is changed from the starting orientation to an intermediate orientation;
• monitoring the intermediate orientation of successive stacks in second portions of the paths downstream of the first portions;
• comparing the monitored orientation of successive stacks with a reference value denoting the desired orientation of stacks in the second portions of said paths;
• and changing the speed of advancement of the second part of a stack along the second path downstream of the second portion of the first path independently of the speed of advancement from the first portion of the second path by changing the speed of one of said second conveyor means located downstream of the second portion of the second path independently of the speed of another of said second conveyor means located upstream of the second portion of the second path when the monitored orientation of such stack deviates from the desired orientation so that each stack assumes a predetermined final orientation not later than upon completion of advancement along said paths.