Abstract: Lateral force is applied to a web material by an air bearing for the purpose of guiding the web against a fixed reference edge. A bearing surface over which the web is movable includes an arrangement of holes for establishing a differential flow across the bearing surface to produce a lateral force on the web in the direction of the reference edge. The holes are arranged asymmetrically relative to the center line of the bearing surface but typically are parallel to the reference edge. The differential air flow is established by controlled sizes of apertures through the bearing plate, variable air permeability of the material forming the bearing surface or the like. A common source of pressurized air is coupled to all of the bearing surface holes.

Abstract: Parallelism between the track on magnetic tape and the path of the rotating head is dynamically adjusted and maintained by adjusting one or both of the entry or exit guides guiding the tape as it helically wraps a mandrel. The mandrel has two halves that flank the rotating head so that as the tape wraps the mandrel, the rotating head traverses the tape at an oblique angle. Skew error is represented by a lack of parallelism between the track on the tape and the path of the rotating head across the tape. The skew error may be corrected by laterally shifting either the entry or exit tape edge guide without distorting the track over a limited lateral range of movement by the guides. The entry and exit edge guides are continuouscompliant air-bearing guides. Similarly, the mandrel that supports the tape adjacent the rotating head is also air bearing.