30/9/1999 · Carrier can range from a simple hook to a hoist to an intelligent-vehicle-like device Single-carrier, single-track monorail similar to bridge or gantry crane Multi-carrier, track network monorail similar to both a trolley conveyor, except that the carriers operate independently and the track need not be in a closed loop, and a fixed-path auto guided vehicle (AGV) system, except that it operates overhead