Overhead single track (i.e., mono-rail) or track network on which one or more carriers ride
Carriers: powered (electrically or pneumatically) or nonpowered
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 automatic guided vehicle (AGV) system, except that it operates overhead
Termed an Automated Electrified Monorail (AEM) system when it has similar control characteristics as an AGV system