A platform unit usable to support and move an item, comprising a base; a conveyor mounted to the base and operative for moving the item parallel to the base, the conveyor being pivotable about a pivot axis extending substantially perpendicular to the base; and a controller for selectively activating the conveyor and for selectively pivoting the conveyor about the pivot axis. Also, a storage system including many of the platform units.

A platform unit usable to support and move an item, comprising a base; a conveyor mounted to the base and operative for moving the item parallel to the base, the conveyor being pivotable about a pivot axis extending substantially perpendicular to the base; and a controller for selectively activating the conveyor and for selectively pivoting the conveyor about the pivot axis. Also, a storage system including many of the platform units.

A load-bearing roller for conveying items includes an outer cylinder and a transmission assembly. The transmission assembly includes a bushing rotatably mounted in an end of the outer cylinder, a transmission member, and a retracting member. The transmission member includes a transmission wheel and a toothed gear non-rotatably coupled to the transmission wheel. The transmission wheel is positioned outside the outer cylinder. The toothed gear is positioned in the bushing. The retracting member is mounted in the bushing. A free end of the retracting member engages with the gear teeth to urge rotation of the bushing and the outer cylinder. When the roller is jammed or prevented from rotating, the retracting member retracts over the teeth of the toothed gear so as to prevent overload of a prime mover. The disclosure also includes a conveying device using the load-bearing roller.

A load-bearing roller for conveying items includes an outer cylinder and a transmission assembly. The transmission assembly includes a bushing rotatably mounted in an end of the outer cylinder, a transmission member, and a retracting member. The transmission member includes a transmission wheel and a toothed gear non-rotatably coupled to the transmission wheel. The transmission wheel is positioned outside the outer cylinder. The toothed gear is positioned in the bushing. The retracting member is mounted in the bushing. A free end of the retracting member engages with the gear teeth to urge rotation of the bushing and the outer cylinder. When the roller is jammed or prevented from rotating, the retracting member retracts over the teeth of the toothed gear so as to prevent overload of a prime mover. The disclosure also includes a conveying device using the load-bearing roller.