A gravity conveyor retarder includes a housing having a cylindrical cavity in which a rotor connected with a rotatable member of the gravity conveyor rotates. The housing includes an annular reservoir surrounding the cavity and separated therefrom by an annular wall provided with a plurality of circumferentially spaced, radially extending, restricted passageways so that, regardless of the circumferential orientation of the housing, any air in the cavity will migrate upwardly therein, through the restricted passageways and accumulate above the liquid level at the upper end of the reservoir.