A rotary cutterbar disk hub assembly for diverting debris includes a cutterbar housing defining an internal cavity and a bearing housing defining an axis and coupled to the cutterbar housing. A labyrinth is defined in the bearing housing circumferentially about the axis, and a barrier is formed by the bearing housing at a location radially outward of the labyrinth. A disk hub is positioned concentric with the axis and coupled to the bearing housing and cutterbar housing. The disk hub forms at least one protrusion that extends towards the bearing housing and is radially adjacent to the labyrinth. The barrier restricts a portion of the debris from entering the labyrinth, and the at least one protrusion severs debris that is disposed near the labyrinth as the disk hub rotates.
