Abstract: A roller cone drill bit having a bit body with at least one support arm extending therefrom. Each support arm may have an interior surface and an exterior surface with an associated spindle extending inwardly from the interior surface. A respective cone assembly may be rotatably disposed on each spindle. A gap may be formed between interior portions of each cone assembly and exterior portions of the associated spindle with a fluid seal disposed in the gap to block fluid flow therethrough. Each cone assembly may include a generally circular backface disposed adjacent to the interior surface of the associated support arm. At least one fluid passageway may extend through each support arm to allow communication of fluid from the interior surface to an exterior surface of the support arm. A debris diverter insert having a generally hollow bore may be disposed within each fluid passageway.

Abstract: A roller cone drill bit having a bit body with at least one support arm extending therefrom. Each support arm may have an interior surface and an exterior surface with an associated spindle extending inwardly from the interior surface. A respective cone assembly may be rotatably disposed on each spindle. A gap may be formed between interior portions of each cone assembly and exterior portions of the associated spindle with a fluid seal disposed in the gap to block fluid flow therethrough. Each cone assembly may include a generally circular backface disposed adjacent to the interior surface of the associated support arm. At least one fluid passageway may extend through each support arm to allow communication of fluid from the interior surface to an exterior surface of the support arm. A debris diverter insert having a generally hollow bore may be disposed within each fluid passageway.

Abstract: A nozzle for a drill bit has an adjustable orifice, allowing a single nozzle to change the pressure drop for a given flow rate. This is accomplished by the use of two plates, each having a shaped aperture therein. The degree to which the two apertures are overlapped determines the size of the orifice. The movement of the apertures, and thus the size of the orifice, can be adjusted at the drilling site.