Abstract: An improved journal bearing for rotary cone type mining or oilfield rock bits is disclosed. Such rock bits typically have several cutters each rotatably mounted on a cantilevered bearing pin. The cutter and respective bearing have complementary journal bearing surfaces. A retainer is provided at one end at the bearing surfaces for keeping the cutter on the bearing pin and a seal is provided at the opposite end. In addition to the usual axial thrust surface located towards the radially inner end of the bearing pin, one or more secondary axial thrust surfaces are provided in one embodiment of the invention. Alternatively, at least one series of grooves or other axial lubricant flow restrictor is provided at the complementary bearing surfaces. The invention greatly improves the load carrying capacity of the bearing.

Abstract: In order to detect when a lubricant is nearly depleted in a lubricant reservoir provided in a sealed rotary cutter rock drill bit, compressed air used for removal of cuttings is passed through a valve in the reservoir. As the lubricant is used up a compressed spring gradually extends. In one embodiment, eventually a vent hole in the valve is opened causing a large pressure drop signifying an empty condition of the reservoir. In another embodiment, the valve is closed when the lubricant is depleted, giving rise to a sudden rise in pressure also signifying an empty condition.

Abstract: An earth boring bit of the type having three rotary cone cutters carried on bearing pins depending from respective head sections is disclosed. Adjacent the rear face of a cutter is located a portion of the respective head section commonly known as the shirttail. The invention discourages the intrusion of cuttings into the bearing surfaces or seals and reduces the likelihood of fracture of the shirttail. This is achieved by forming the coacting faces as truncated conical surfaces instead of the usual configuration of the prior art which is arranged substantially perpendicular to the bearing pin axis.

Abstract: The invention relates to a guide bushing used to maintain alignment of a rotary shaft and in particular to a guide bushing for use as a mining deck bushing. When drilling blast holes in surface mining operations, it is conventional to pass the drill pipe through a deck bushing located on the floor or deck of the blast hole drill. During drilling operations the drill pipe has a tendency to run off laterally, and vibrate vertically. The purpose of the deck bushing is to keep the drill pipe as straight as possible, and prevent wear of the more costly deck. The present invention provides a guide bushing for use as a deck bushing and is equipped with a rotatable inner sleeve which is supported by angular journal bearing surfaces and ball bearings located in elongate annular grooves, which allow the guide bushing to maintain alignment of the drill pipe without premature failure of the ball bearings, grooves or other bearing surfaces.

Abstract: A percussion drill bit has an anvil portion and a removable head porton incorporating cutting inserts arranged in circumferentially-spaced groups separated by fluid flow passageways, at least some of the inserts being arranged at axial and radial positions with respect to the drill axis so that during working operation these inserts penetrate the formation being drilled by generally equal amounts and are thus subject to generally the same loading. The removable head portion is retained on the anvil portion of the bit by a splined and threaded lock nut arranged so that the threads are not subjected to cyclical fatigue loading due to operation of the percussion force generating tool.

Abstract: A drill of the type comprising a pilot point for locating the drill in a medium to be drilled and cutting means extending from the pilot point and having a radially outermost portion which defines the radius of the hole to be drilled and which precedes a radially inner portion into the medium both axially and radially to promote fracture of the medium laterally of the direction of drilling and thereby to facilitate drill penetration into the medium.

Abstract: In known cutter assemblies, a cutter bit is dragged through a formation, thereby producing an unbalanced moment on the cutter bit which causes it to rotate. However, cuttings can lodge between the cutter bit and the holder, resulting in a frictional force greater than the unbalanced moment tending to rotate the cutter bit. The dragging of the cutter bit through a formation without its rotating causes the cutter bit to wear rapidly, necessitating its frequent replacement. The subject invention proposes to overcome the frictional force and to thereby increase the wear life of the cutter bit, by providing means whereby rotation is imparted to the cutter bit upon its initial contact with a formation. Thus, the inventive cutter assembly has a longitudinally and angularly extending groove situated on one of the cutter bit and the holder and a follower located on the other of the holder and the cutter bit.

Abstract: A percussion drill bit has an anvil portion and a removable head portion incorporating cutting inserts arranged in circumferentially-spaced groups separated by fluid flow passageways, at least some of the inserts being arranged at axial and radial positions with respect to the drill axis so that during working operation these inserts penetrate the formation being drilled by generally equal amounts and are thus subject to generally the same loading. The removable head portion is retained on the anvil portion of the bit by a splined and threaded lock nut arranged so that the threads are not subjected to cyclical fatigue loading due to operation of the percussion force generating tool.