Abstract: Web support for constraining the entering portion of a moving web against change in its spatial lateral position while remaining free to change its angular lateral position. The web support includes a web engaging surface which presents substantially no lateral resistance to the entering position of the moving web, and opposed edge guides mounted in a predetermined position on a fixed frame adjacent to the web engaging surface. The edge guides have opposed web engaging portions a fixed distance apart which distance corresponds substantially to the width of the moving web.

Abstract: Web tracking apparatus for a flexible, closed loop web moving in a closed loop path defined by two or more cylindrical, hard surface supports mounted on a frame and having substantially parallel longitudinal axes which are substantially perpendicular to a plane passing through the respective midpoints of the supports. Included are at least two laterally constraining web supports, at least one of which is a passive positional lateral constraint and includes a cylindrical web-engaging surface which presents substantially no resistance to lateral movement of the moving web, and edge guides mounted adjacent to the cylindrical surface in a predetermined spatial relation to the frame, and having spaced web engaging portions fixed a distance apart which corresponds substantially to width of the web for engaging the edges of the moving web.