| 摘要 |
A printing web tensioning system that is activated in response to a break in the printing web. The system includes a pair of tensioning rollers which bracket the paper web and are movable between a spaced disengaged position and a contacting engaged position. The pair of tensioning rollers are driven by a variable speed motor, the speed of which is synchornized with the speed of the printing cylinders. Hydraulic rams are attached to the tensioning rollers to move them from the disengaged position to the engaged position when a break in the printing web is detected and the printing unit begins to shut down. Since the speed of the tensioning rollers is synchronized with the speed of the printing cylinders, web tension is maintained and a small quantity of paper web is advanced forward and collects on the floor during the shut down process. By maintaining tension on the printing web, paper is prevented from wrapping around the printing cylinders and causing damage to the print blankets.
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