Abstract: An underreamer is disclosed having longitudinally telescoping upper and lower portions connectable respectively to an upper drill string and a lower drill string. A splined connection is provided between the telescoping portions having first and second engaged positions. Both of the engaged positions transmit torque between the telescoping portions. The splined connection provides a different angular and a different longitudinal position for the telescoping portions in each such position. Means is provided for pivotally mounting a cutter arm on one of the telescoping portions. Means is provided on the other telescoping portion for urging the at least one cutter arm relatively outward from the telescoping portions to an extended underreaming position when the splined connection is in its first position. The cutter arm is positioned inwardly to a retracted clearance position when the splined connection is in its second position.

Abstract: Apparatus is disclosed for use in a drill string during rotary well drilling, especially of shallow holes such as blast holes, to absorb the shock loads imposed upon the drill bit and drill. A floating solid piston in an outer tubular body separates a gas chamber from a liquid chamber and equalizes the pressure between the two. A mandrel with large diameter bearing surfaces is carried reciprocally within the body, and has annular lubricating cavities separated from the liquid chamber. Lubricating passages include one in which a pressurized gas in a cavity supplies lubricant under pressure to the various bearing and sealing surfaces. Cylindrical pins inserted between the mandrel and the outer tubular body transmit torque between the body and mandrel.

Abstract: A telescoping torque transmission apparatus including an inner mandrel of upper and lower sections, a sleeve surrounding the mandrel and slidable thereon, a splined drive connection between the sleeve and mandrel with drive keys interposed between all drive surfaces of the spline drive, cartridge seals sealing above and below the spline drive and also defining upper and lower balance chambers between said mandrel and said sleeve, a port through said sleeve communicating with one of said chambers, a port through said mandrel communicating with the other of said chambers, a keyed lock ring having teeth to engage teeth on the upper end of the lower mandrel section and keyed to engage in the spline key ways of the upper mandrel section, a lock ring threaded on the lower end of the upper mandrel section to retain the keyed lock ring in engagement with the lower section teeth to prevent unthreading of the lower mandrel from the upper mandrel and a pressure equalizing valve communicating with the spline drive chambe

Abstract: The shaft of a drill steel for down-hole drills having a longitudinally grooved outside is detachably connected to a bore crown widened out towards the working surface and fitted with flush bores, cavities and hard metal inserts. The bore crown is larger in diameter than the drill steel shaft and is interchangeably secured to it. Form-locking companion parts may be axially and/or tangentially cushioned by elastic material, e.g. by resilient pads located under stress between the lower shaft end and an inner wear bit face. A central passage in said shaft is continued through a central resilient pad that can be made up of two integrally joined parts having different mechanical properties. Preferably, shaft and wear bit have matching disharmonic polygonal profiles. Fastening ring and stop means for the detachable yet secure connection of shaft and wear bit are preferred to use a thread of symmetrical, rounded thread-pitch turning in the same direction as the down-hole drill.

Abstract: A shock absorbing subassembly with a body, a mandrel slidably and non-rotatively received in the body, dampening means therebetween, an upper seal above the dampening means and a floating seal therebelow for maintaining an oil bath between the body and the mandrel, a primary seal between the body and the mandrel below the floating seal, and a secondary seal actuated upon a predetermined magnitude of leakage past the primary seal to sequentially establish another seal between the body and the mandrel above the primary seal and below the floating seal.

Abstract: There is disclosed a tool which is connectible as part of a drill string and which is adapted, upon lifting of the drill string, to permit drilling fluid therein to by-pass a motor in the lower end of the string below the tool.

Abstract: The specification describes a drilling jar for connection in a rotary drill string. There is a trap space in the jar for collecting the products of wear between its moving parts. The drilling jar includes a generally tubular housing assembly, which has near its bottom, a wash pipe sleeve. There is a tubular mandrel assembly extending into the housing and movable with respect to it, which has near its bottom a wash pipe that slides in the sleeve. An annular trap space is defined near the top of the sleeve between its outer surface and an inner surface of the housing. Wear products are collected in the trap space and thereby prevented from entering between the wash pipe and sleeve where they would cause abrasion.

Abstract: A sub is screwed to the top of a down hole percussor. A replaceable stabilizer sleeve is screwed to the sub and extends down around the percussor body spaced radially therefrom. A rubber shock ring inside the lower end of the sleeve centralizes the sleeve relative to the percussor body.

Abstract: A uniquely integrated arrangement of concentric tubes in combination with concentric pistons and special interconnecting fluid pressure passages therein, said component members cooperating in a manner as to permit extreme compound extension or retraction, while special cross-section configuration allows efficient transmission of axial torque energy without slippage between collinear members, so that when driven as a Kelly drive for earth drilling the torque is transmitted to a drilling auger.

Abstract: A shock absorbing tool is provided having a low spring rate deformable element disposed in an oil bath in a sealed, annular chamber formed between the barrel and mandrel. One of the chamber seals is a floating seal, exposed to the drilling fluid outside the tool so that the pressure within the chamber is equalized with the hydrostatic bottom hole pressure. As a result, the tool is not pre-loaded, when lowered to the bottom of the well bore, leaving the most effective shock-absorbing capability of the element available to absorb the axial thrusts of the drilling bit.