Bottom stacking apparatus for stacking mailpieces

An apparatus for stacking material pieces in a vertical stack, the apparatus comprising:

• a first stacking element approximately S-shaped in cross section, adapted to rotate in a counter-clockwise direction having an axis of rotation at about the center of the first stacking element and positioned in a first plane;
• a second stacking element approximately S-shaped in cross section, adapted to rotate in a clockwise direction having an axis of rotation at about the center of the second stacking element and positioned in the first plane at a predetermined distance from the axis of rotation of the first stacking element, the second stacking element having an axially inverted orientation with respect to the first stacking element;
• the first stacking element comprising a first shelf extending about perpendicularly from the axis of rotation of the first stacking element;
• the second stacking element comprising a second shelf extending about perpendicularly from the axis of rotation of the second stacking element;
• whereby the first and second shelves provide support for outer portions of a material piece that is to be added to the bottom of the stack;
• whereby the stacking elements operate in concert with each other by rotating and lifting the material piece to the bottom of the stack, and
• wherein the second stacking element is configured to move linearly in the first plane such that linear movement causes the distance between the first stacking element and the second stacking element to increase or decrease depending upon the direction of movement and whereby the linear movement allows the stacker to accommodate material pieces of various widths.