Air circulation ports in rotary rock bit journal bearing

A thrust bearing system for a roller cone rock bit includes at least one roller cone disposed on a leg having an air channel therethrough, the thrust bearing system including a primary thrust bearing surface on the leg configured to contact a corresponding primary bearing surface on the roller cone, wherein the primary thrust bearing surface on the leg includes at least one air circulation port in fluid communication with the air channel. The thrust bearing system further includes a secondary thrust bearing surface on the leg configured to contact a corresponding secondary bearing surface on the roller cone, wherein the secondary thrust bearing surface on the leg includes at least two air circulation ports located at specified locations in the secondary bearing surface and in communication with the air channel, and wherein a first circulation port is located in an upper half of the secondary thrust bearing surface and a second circulation port is located in a lower half of the secondary thrust bearing surface.