Importance

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Abstract

Signatures are delivered to a stacker by a gripper conveyor, each gripper delivering a signature thereto. The grippers follow a curved path adjacent to the stacker, substantially aligning the signatures with the stacking platform receiving signatures as they are released. A plurality of stacking platforms are moved about a closed loop path, each independently driven by an associated drive motor. The speed of each stacking platform is variable and is synchronized with the throughput of the gripper conveyor as well as signature thickness. When a predetermined quantity of signatures has been collected, an upstream stacking platform is moved between the last signature of the preceding stack and the first signature of the next stack. When a stack has been completed, the stacking platform is quickly pulled away from the signature stack allowing it to fall by gravity into a collector, and is thereafter moved quickly to the ready position in preparation for forming a subsequent signature stack. The stacker has three stacking platforms independently driven by an associated motor. Three drive chain sets arranged to move about only two shafts each drive an associated stacking platform.

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First Claim