A conveyor includes a conveyor belt, a plurality of rollers, and a flight. The rollers have lower surfaces configured to engage a roller-engagement surface, and upper surfaces that substantially form a plane, such that the rollers engage the roller-engagement surface and rotate to move an object supported by the rollers over the plane. The flight includes a cam configured to engage a cam surface below the conveyor belt to impart a moment on the flight, and a projection that responds to the moment by rotating from a retracted position to an extended position.