Abstract: A tensioner assembly pre-stretches a film web prior to unitizing a pallet load. The film web undergoes three stages of stretching by the tensioner assembly which includes two driven rollers and a resiliently biased dancer roller. The dancer roller engages the film and maintains it under continuous tension loading as the pallet load rotates. An electrical control signal proportional to the angular position of the dancer roller is employed by a control circuit to vary the rotational speed of the pretensioner drive rollers. The film web is stretched in a first stage between a feedstock roll and the first drive roller. A second stage of stretching occurs between the first driven roller and the second driven roller. Finally, the film web undergoes a third stage of stretching between the second driven roller and the pallet load, with the web being maintained under tension at all times by the resiliently biased dancer roller.

Abstract: An elongated, resilient member such as a coiled spring or a belt of elastic material is disposed in lapping engagement with first and second drive rollers for engaging and threading a web around the rollers in response to rotation of the rollers. The drive rollers are rotated in opposite directions and the belt or spring is disposed in a twist, thereby defining a figure "8" lapping pattern. In a preferred embodiment, each roller is circumscribed by a groove in which the spring or belt is reeved.