A downhole tool for use in a downhole drill string is provided. The downhole tool includes a rotor movably coupled within a stator, and a drive shaft movably coupled within a bearing housing. The drive shaft has a first end coupled with the rotor and a second end coupled with a drill bit. Bearing assemblies interfaces engagement between the drive shaft and the bearing housing, including polycrystalline diamond elements, each with an engagement surface, and an opposing engagement surface of a non-superhard metal.

A bearing assembly having independently rotatable concentric inner and outer tubes. A bearing chamber containing multiple bearings is disposed between the tubes, allowing thrust but not rotation to be transferred between them. The bearing chamber is sealed from the inside of the inner tube. To prevent high pressure fluid from leaking from the inner tube to an exterior of the tool through the bearing chamber, damaging components, a flow path is formed. An annular piston responds to high pressure within the bearing chamber and the inner tube, opening a flow path from the inner tube to the environment.

Embodiments of the invention relate to tilting pad bearing assemblies and apparatuses. The disclosed tilting pad bearing assemblies and apparatuses may be employed in downhole motors of a subterranean drilling system or other mechanical systems. In an embodiment, a bearing assembly or apparatus includes a support ring and a plurality of tilting pads. Each tilting pad is tilted and/or tiltably secured relative to the support ring. In some embodiments, one or more of the tilting pads include a plurality of superhard bearing segments assembled to form a superhard bearing surface. One or more seams may be positioned between adjacent superhard bearing segments of the superhard bearing segments. In other embodiments, one or more of the tilting pads may include at least one or only one superhard bearing segment, such as a polycrystalline diamond bearing segment.

A coating architecture is disclosed that includes a substrate having a surface finish R.sub.a of 0.3μ or finer, an intermediate layer overlying and in contact with the substrate; and a solid lubricant layer overlying and in contact with the intermediate layer. The test results of applying the coating architecture to a reciprocating hammer drill utilizing the coating is also disclosed.

A downhole-type system includes a rotatable shaft; a sensor that can sense an axial position of the shaft and generate a first signal corresponding to the axial position of the shaft; a controller coupled to the sensor, in which the controller can receive the first signal generated by the sensor, determine an amount of axial force to apply to the shaft to maintain a target axial position of the shaft, and transmit a second signal corresponding to the determined amount of axial force; and multiple magnetic thrust bearings coupled to the shaft and the controller, in which each magnetic thrust bearing can receive the second signal from the controller and modify a load, corresponding to the second signal, on the shaft to maintain the target axial position of the shaft.

A safety catch assembly design to prevent loss of drilling components during downhole operation is disclosed. The safety catch assembly can include a lower inner radial bearing comprising a catch ring retention zone. The safety catch assembly can also include one or more catch rings removably disposed in the catch ring retention zone, including a first catch ring having one or more ridges about its inner diameter and a second catch ring having one or more ridges about its inner diameter. In a locked position, the catch rings can retain the drilling components during a failure event.

A harmonic gear drive includes an input shaft and an output shaft. The input shaft is mechanically coupled to a wave generator which has a varying diameter. The wave generator is positioned within a flex spline which includes external teeth. The external teeth of the flex spline engage with internal teeth of a fixed spline and an output spline when the major diameter of the wave generator is aligned therewith. The output spline has a different number of teeth from the input spline such that, as the wave generator is rotated and the flex spline rotates, the output spline is rotated relative to the fixed spline.

A drive shaft assembly for a down hole drilling motor is provided. The drive shaft assembly includes a drive shaft having a first end portion engaging a first housing and a second end portion, engaging a second housing. The first end portion and the first housing form the first constant velocity joint and the second end portion and the second housing form the second constant velocity joint of the drive shaft assembly. Each end portion including a base surface having a pair of prongs extending away from the base surface and a cylindrical side wall having a plurality of ball bearings held in a plurality of circumferentially spaced pockets. Each housing includes a cavity to retain respective end portions of the drive shaft. An inner side wall of each housing includes a plurality of cylindrical grooves to receive the plurality of ball bearings to transfer torque. An internal wall of the housing includes a first chamber and a second chamber to receive and retain the first prong and the second prong to transfer torque and thrust loads between the shaft and the housings.

Methods and systems are provided to adaptively control a hydraulic fluid supply to supply a driving fluid for applying a driving force on a piston in a gas compressor, the driving force being cyclically reversed between a first direction and a second direction to cause the piston to reciprocate in strokes. During a first stroke of the piston, a speed of the piston, a temperature of the driving fluid, and a load pressure applied to the piston is monitored. Reversal of the driving force after the first stroke is controlled based on the speed, load pressure, and temperature.

Methods and systems are provided to adaptively control a hydraulic fluid supply to supply a driving fluid for applying a driving force on a piston in a gas compressor, the driving force being cyclically reversed between a first direction and a second direction to cause the piston to reciprocate in strokes. During a first stroke of the piston, a speed of the piston, a temperature of the driving fluid, and a load pressure applied to the piston is monitored. Reversal of the driving force after the first stroke is controlled based on the speed, load pressure, and temperature.