Apparatus for providing selectively differentiated vacuum across a papermaking machine width

摘要

Mechanism for automatically controlling and maintaining a selectively differentiated vacuum pressure in a vacuum head accommodating to the transverse width of a moving web passing relative thereto involving means for supplying air to the vacuum head at spaced points along the width and control means for detecting the need for an increase or decrease in the vacuum at the spaced points along the length and selectively charging more or less air to the vacuum head at the corresponding points along the length.