Abstract: A conveyor idler includes a drum having an outer surface and an inner surface, a shaft (24) about which the drum can rotate in a forward direction, a locking mechanism for preventing the drum from rotating in a reverse direction (R) but which locking mechanism permits rotation of the drum in the forward direction, the locking mechanism having at least one wedging surface (44) fixed directly or indirectly to the drum, and a locking member (38) interposed between the wedging surface and the shaft, the locking member being rotatable about the shaft when the drum rotates in the forward direction, but when an attempt is made to rotate the drum in the reverse direction the locking member becomes releasably wedged between the wedging surface and the shaft, or a surface fixed to the shaft, thereby preventing the drum from rotating in the reverse direction.