Abstract: A well drilling bit comprises a bit body with a centralized portion and a plurality of radially and circumferentially spaced legs depending longitudinally therefrom. A respective cutter body is rotatably mounted on the free end of each leg with bearing means. The bit body has a respective lubricant passage communicating with each bearing and a respective upwardly opening lubricant reservoir recess, the recess also communicating with a respective vent port opening downwardly through the bit body. A respective lubricating mechanism is disclosed in each lubricant reservoir recess, and each such mechanism comprises an elastomeric pressure compensating diaphragm extending across the recess and sealed with respect thereto, dividing the recess into a lower portion communicating with the vent port and an upper portion communicating with the lubricant passage.

Abstract: An improved pressure compensator of the top-vented type for a roller cone drill bit comprises an elastomeric compensator diaphragm having an annular, peripheral, radially outwardly extending flange. An annular, axially acting compression spring is at least partially imbedded in the flange, elastomeric material of the flange at least partially underlying and overlying the spring for sealing engagement, respectively, with an axially facing shoulder in a recess in the bit body and a cap forming part of the assembly. The cap is disposed above the flange in the bit recess, and has a lower end surface for sealing abutment with the flange. The cap also has a vent communicating a zone above the diaphragm, in the recess, with the exterior of the bit. A retainer is positioned to hold the cap in the recess, thereby also retaining the diaphragm in the recess, and compressing the spring sufficiently to cause sealing engagement on both sides of the flange, but not beyond the elastic limit of the spring.

Abstract: A method of manufacturing a roller cone type drill bit, or main body thereof, includes forging a monolithic main body forging comprising a shank blank extending longitudinally at one end and a plurality of circumferentially spaced leg stubs at the other end; turning the shank blank to form a threaded section; rotatably mounting a respective roller cone on each of a plurality of journal members, each journal member being carried at one end of a respective leg extension; and welding a respective one of the leg extensions to each of the leg stubs. The main body is forged with its longitudinal centerline perpendicular to its flash line, the latter being located well inward of the leg end of the forging.

Abstract: A lubrication system for an earth boring drill bit having a pressure compensator for minimizing the pressure differential between the drill bit lubricant and the well bore fluid is improved in a manner to prevent sharp edges in the lubricant reservoir wall from damaging the flexible diaphragm and for enabling the lubricant space available in the lubricant reservoir to be maximized. In accordance with a preferred embodiment, the pressure compensator is positioned on a shoulder ring in the lubricant reservoir and the shoulder ring retains the open end of a pressure diaphragm within an interior recess of a compensator cap, the diaphragm sealing against a perimetric wall of the recess. Methods of filling the lubrication system with the pressure compensator installed or removed are provided which avoid stretching or damage to the diaphragm while still maximally filling of the lubrication system with lubricant.

Abstract: An improved nozzle retention system in an earth boring bit of the rolling cutter type using a pliable coating bonded to a nozzle retention snap ring in a manner to permit normal seating of the snap ring by bonding the coating only to the inner periphery and portion of a lower surface of the snap ring. The coating material disclosed is elastomeric, including nitrile rubber.

Abstract: An earth boring drill bit has a lubricant pressure compensator that includes a plunger that moves slidingly in the reservoir to reduce pressure differential, and also allows lubricant to bleed past to relieve excess lubricant pressure. The plunger is carried slidingly in the reservoir. The plunger has a convex end in contact with the lubricant and a concave end in contact with the borehole fluid. The plunger has a rod that contacts a stop in the reservoir when the lubricant pressure is greater than the borehole pressure. Once stopped, the configuration of the plunger allows lubricant to bleed past the plunger to relieve excess lubricant pressure.

Abstract: An improved pressure compensator for earth boring drill bits for minimizing the pressure differential between the lubricant and the well bore. A flexible diaphragm is located in the lubricant reservoir for separating the lubricant from the borehole fluid. The diaphragm is positioned in the reservoir so that a substantial void space exists on the borehole fluid side of the reservoir. A retainer holds the diaphragm in this position, requiring a positive lubricant pressure to stretch the diaphragm in order to fill the void space. For lubricating the bit, the lubricant is introduced under pressure sufficient to stretch the diaphragm. The lubricant pressure is then released, allowing the compensator to return to its original shape which in turn causes the excess lubricant to be expelled. This assures complete filling and a desired void space.

Abstract: Disclosed herein for use with earth penetrating tools is an improved lubricant pressure relief system that utilizes a housing adapted for retention within a lubricant containing passage. An interior surface or opening of the housing is exposed to the lubricant in the passage and includes an outlet port which has an elastic pressure responsive valve covering the opening. The valve releases lubricant when a selected pressure is exceeded while excluding the entrance of exterior matter. The valve functions as a secondary pressure relief valve when used in combination with a spring biased pressure relief valve located within the opening of the housing, which is thereby protected from exterior matter and its successful operation assured.