Patent ID: 8337085

Claim:
A roller cone rock bit for forming a bore hole, the rock bit comprising: a bit body having an end for connection to a drillstring; a plurality of angularly spaced support legs extending from the bit body with each support leg having a journal bearing on an end thereof; each journal bearing having: a primary thrust bearing surface; an air circulation port in the primary thrust bearing surface; a secondary thrust bearing surface; a first air circulation port located in an upper 180 degree section of the secondary thrust bearing surface, wherein the first air circulation port in the upper 180 degree section is located within a range of about 10 degrees to about 80 degrees measured clockwise from a vertical axis through a center of the secondary thrust bearing surface and a second air circulation port located in a lower 180 degree section of the secondary thrust bearing surface, wherein the second air circulation port in the lower 180 degree section is located within a range of about 40 degrees to about 80 degrees measured clockwise from the vertical axis through the center of the secondary thrust bearing surface.