Abstract: An improved seal assembly for utilization with earth boring drilling bits employing roller cutters. The improved seal is constructed utilizing two resilient O-rings or other resilient seals engaging opposing surfaces in the roller cutter and the corner formed by the shaft and face of the cutter support. The O-rings are mounted in and separated by a flexible floating ring of slightly harder material than the O-ring material. The flexible floating ring may be coated with or made from a material which provides a low coefficient of friction, permitting the O-rings to rotate therein. In an alternate embodiment of the present invention the flexible floating ring is tapered so that increased loading of the earth boring drilling bit will result in increased compression of the resilient O-rings, thus improving the seal under high load conditions.

Abstract: A rock bit having a seal protector positioned within each seal gland for eliminating shale packing behind the seal and restricting the axial movement of the seal. The rock bit includes a bit body having a plurality of legs depending therefrom, each leg having a cutter rotatively mounted thereon. A seal is positioned between each cutter and leg to prevent lubricant from leaking to the exterior of the bit and prevent drilling fluid, shale or the like from entering into the bearing area. Each seal protector comprises an annular ring located within each gland on the side of the seal facing the exterior of the bit. The annular ring extends the full length of the gland between the cutter and leg for preventing the shale and other debris from passing therethrough to attack the seal. The annular ring also fully extends across the clearance between the seal and the gland width to restrict the seal from axial movement due to internal and external pressure differentials and prevent the seal from bunching or wrapping up.

Abstract: The cone cutter of each segment of a multi-segment rock bit is assembled onto its segment. A pin end of the segment is supported by an index pin and axially constrained in the direction away from the cone cutter. The cone cutter is clamped against and dimensionally indexed on a cone saddle having a circular surface of a diameter corresponding to the gage diameter of the completed rock bit. The cone is loaded in a direction axially of the segment in a manner to simulate the loading of the hole bottom that is to be drilled by the rock bit. The segment away from the cone is also loaded radially of the axis of the segment to take up tolerances along the axis of rotation of the cone cutter. The constraint of the cone and loading of the segment simulate the hole wall force on the cone experienced at the gage row and takes up tolerances radially of the axis of rotation of the cone along a line to the gage row in contact with formation material. A bridge prevents rotation of the segment about its lengthwise axis.