Abstract: A shuttle driving assembly (10) including an open shuttle (22) rotatably driven on an automatically opened support frame (16) by a plurality of drive roller assemblies (85,87) carried by the frame (16). Each drive roller assembly (85,87) has a drive roller pulley (84) and at least one with plural belts (192,191,190,188,186) driving groups of the drive roller assemblies. The drive rollers contact a groove (115) on the shuttle (22) to provide a positive and responsive power transmission therebetween. The shaft (82) of each drive roller assembly (85,87) is mounted in a non-concentric bearing in a web (30) of the support frame (16) to provide adjustment of the position of the drive rollers (92) relative to the shuttle (22) for centering the shuttle (22) relative to the frame (16).