Abstract: A conveyor of the low density type comprises two spaced-apart roller assemblies around which an endless wire is entrained to form upper and lower flights consisting of parallel spaced-apart wire lengths. Each roller assembly includes grooved discs or pulleys to support the successive lengths of wire of the flights, the pulleys being mounted on a shaft so as to be independently rotatable. A drive to one of the assemblies includes a slipping clutch to an end pulley, and the remaining pulleys are in frictional engagement so that the drive is transmitted to all the pulleys in that assembly.