| 摘要 |
In order to provide controlled resilient biasing of a movable check roller (13) that roller is mounted on a first leg (15) of a torsion bar (17), the torsion bar (17) having a generally U-shaped portion (18) which lies in a plane which is normal to that of leg (15), and right-angle bend portions (21, 22) restrained to a mounting bracket (1) by hook portions (23) of the bracket. A second roller (14) is conveniently mounted on a second leg (16) of the bar (17). The mounting bracket (1) is of generally S-shape with the rollers being retained between two limbs of the S-shape. |
