| 摘要 |
To capture a torn web traveling at high speed after receiving printed subject matter from a printing machine, the web is guided between a pair of capturing rollers (1, 55) which, in normal operation, pass the web without contact with the rollers therebetween. Upon sensing of a torn web, a "torn web" signal modifies the diameter of one of the rollers to engage against the other, with the torn web therebetween. This system eliminates moving the axes of rotation of the rollers. Expansion of the diameter of the expandable roller is achieved by forming the roller of part-cylindrical segments which are retained by pivot levers (9, 54) on a rotating spindle (13), the levers being movable under spring pressure (16) from a sharply inclined to a more erected position to thereby move the segments (2, 3, 4) outwardly. A sear (20, 21) releases spring pressure. Centrifugal force due to rotation of the rollers assists in rapid expansion of the effective diameter of the expandable roller.
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