Patent ID: 8276740

Claim:
A material handling system for sorting or retrieving a plurality of items, comprising: a plurality of destination areas for items, wherein the destination areas are arranged in a plurality of columns or rows; a plurality of vehicles for transporting items to or from the destination areas; and a track for guiding the delivery vehicles to the destination areas, wherein the track comprises a plurality of columns or rows adjacent the plurality of destination areas, wherein the track comprises engagement elements; wherein at least one of the vehicles comprises: a motor for driving the vehicle to one of the destination areas; a drive system cooperable with the track to guide the vehicle to one of the destination areas, wherein the drive system comprises a plurality of teeth that mesh with the engagement elements on the track, and wherein the drive system is operable to maintain the orientation of the vehicle relative to the horizon as the vehicle changes from a first direction of travel to a second direction of travel, wherein the first direction is at an angle to the second direction; and a transfer mechanism for transferring an item between the vehicle and one of the destination areas, wherein the transfer mechanism is operable to transfer the item along a third direction that is transverse both the first and second directions.