| 摘要 |
The drive chains which are operative to intermittently move a series of gripper bars for conveying sheets through a printing press or the like each pass around a sprocket which is supported for movement in a direction aligned with the path of travel of the sheets. A pair of hydraulic pistons are provided for urging the sprockets for movement in a direction serving to maintain tension on the drive chains. When the gripper bars are stopped momentarily for seizing a sheet and for registering a sheet immediately prior to printing, cutting, or the like, excess chain movement is absorbed by the hydraulic pistons. A timing cam controls the operation of valves in the hydraulic system connected with the pistons, to regulate the supply of hydraulic fluid to the pistons in synchronism with the operation of the printing press. |
