1) Power and free conveyor
A variation of overhead chain conveyor is "power and free". In a conventional overhead conveyor the carrier is permanently fastened to the drive chain, in the power and free case the carrier can mechanically disengage from the drive chain and essentially idle while the chain continues to move. Power and free conveyors can also be inverted so that they can be mounted to the floor, in which case the carrier or tray rides on top of the guiding rail as opposed to being suspended beneath it.