Patent ID: 7837189

Claim:
A stacker for forming a stack of stackable items, comprising: at least one rotational element, each rotational element having an outer periphery and at least one slot breaking into the outer periphery, each slot dimensioned for receipt of at least a portion of a stackable item; a feed mechanism to receive a stackable item and to feed the stackable item into one of the at least one slot in the at least one rotational element; a gripper surface positioned in relationship to the at least one rotational element so as to exert a force on the stackable item that has been received within the slot of the at least one rotational element; and a mechanical linkage coupled to the gripper surface being cooperable with the at least one rotational element to vary the force on the stackable item that has been received within the slot of the at least one rotational element, wherein the mechanical linkage comprises a counterweight arm to vary the gripper surface in a direction that increases or decreases the exerted force.