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.