Patent ID: 7708090
Filing Date: 2010-05-04
Classification: E21B

Abstract:
1. An earth boring bit having a body with a depending bearing pin, and a cone rotatably mounted to the bearing pin, the cone having a plurality of cutting elements, the improvement comprising: an elastomeric seal ring having an outer portion in sealing engagement with a seal surface on the cone and an inner portion; an annular recess formed in the inner portion, defining an interior section on one lateral side of the recess and an exterior section on the other lateral side of the recess, the interior and the exterior sections of the inner portion being in dynamic sealing engagement with a seal surface on the bearing pin; and at least one excluder ring carried within the annular recess of the seal ring and having a face urged by the seal ring into sliding contact with the seal surface on the bearing pin, the excluder ring being of a material that differs from the seal ring, provides lubrication to the seal surface on the bearing pin, but not seal as well as the seal ring and has less wear resistance than the seal ring.