Seal assembly for rolling cutter drill bits

摘要: A rolling cutter drill bit has at least one roller (118) mounted on a cantilevered bearing shaft (116) with sealed and lubrication system, lubricant pressure balancing means (28), relief means, volume compensating rigid face seal assembly (132) axially movable through an operating range. The comprises two cooperating rings, ring (144) the other (146) in cutter; first energizer (148) for shaft, having stiffness K1; second (150) cutter, K2. In order to minimise variation sealing force as moves its range, K2 is less than half, preferably .2, of K1.