A sealing assembly having a housing having a main cavity, a sealing unit configured to receive a rotatable shaft, and at least a first sealing element, and a second sealing element positioned uphole with respect to the first sealing element along the longitudinal axis. The sealing assembly includes a first valve carried by the housing and coupled to the first sealing element and the main cavity, and configured to open at a first pressure level. The sealing assembly further includes a second valve coupled to the second sealing element and the main cavity, and configured to open at a second pressure level higher than the first pressure level. The sealing assembly is configured such that pressure is distributed across the first and second sealing elements sequentially.

A bearing assembly includes a support ring circumferentially surrounding a central bearing axis and a plurality of superhard bearing elements coupled to the support ring. Each of the plurality of superhard bearing elements has a base, a superhard bearing surface, and a lateral periphery extending between the base and the superhard bearing surface. The superhard bearing surface has a partial-ellipsoidal surface shape. A bearing apparatus includes an inner bearing assembly and an outer bearing assembly. A subterranean drilling system includes an output shaft operably coupled to a bearing apparatus.

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 constant velocity joint for downhole power transmission has a first insert mounted in a radially extending drive shaft arm. The first insert engages a second insert mounted along a slot formed in a tubular housing disposed to receive the arm. The material for the two inserts may be different, having different galling properties. An insert may be shaped to have at least a flat surface, a cylindrical surface intersecting the flat surface, and a conical surface intersecting the cylindrical surface. The inserts may extend beyond the cavities in which they are mounted. Opposing cavity walls adjacent the cavity opening may be angled away from one another to permit the insert to flex under a load. The back wall of a cavity and back surface of an insert may be arcuate to permit rotational movement of the insert under a load.

A piston actuated drilling tool includes a housing, a top sub, a piston and a drive sub. The piston has a nose at its forward end that is slidably mounted for reciprocating movement within the housing and which strikes a mandrel located at the forward end of the housing. An integrated retaining and bushing system has a retaining ring arranged for preventing the mandrel from detaching from the rest of the tool. The retaining ring encases a bushing for co-operation with the piston nose to stabilise and guide the piston and provide a timing event for percussion of the tool.

A sealing assembly having a housing having a main cavity, a sealing unit configured to receive a rotatable shaft, and at least a first sealing element, and a second sealing element positioned uphole with respect to the first sealing element along the longitudinal axis. The sealing assembly includes a first valve carried by the housing and coupled to the first sealing element and the main cavity, and configured to open at a first pressure level. The sealing assembly further includes a second valve coupled to the second sealing element and the main cavity, and configured to open at a second pressure level higher than the first pressure level. The sealing assembly is configured such that pressure is distributed across the first and second sealing elements sequentially.

A downhole-type device includes an electric machine. The electric machine includes an electrical rotor configured to couple with a device to drive or be driven by the electric machine. An electrical stator surrounds the electric rotor. The electric stator includes a seal configured to isolate stator windings from an outside, downhole environment. An inner surface of the seal and an outer surface of the electric rotor define an annulus exposed to the outside environment. A bearing couples the electric rotor to the electric stator. A lubrication system is fluidically coupled to the downhole-type device. The lubrication system includes a topside pressure pump and a downhole-type distribution manifold configured to be used within a wellbore. The distribution manifold is fluidically connected to the topside pressure pump and the bearing to receive a flow of lubricant from the topside pressure pump.

Methods, systems, and apparatus for imparting and limiting hypocycloidal, lateral, and torsional forces onto drill bits are provided, including hypocycloidal bearings for limiting hypocycloidal motion, lateral impulse mechanisms for imparting lateral movement to a drill bit, and torsional impulse mechanisms for imparting torsional movement to a drill bit. The methods systems, and apparatus may decrease friction, increase drilling efficiency, and provide additional benefits to drilling systems.

A downhole assembly and method are provided for selective activation of a motor in a drilling string. The downhole assembly includes a stator and a rotor assembly. The rotor assembly comprises a rotor body having a fluid passage extending between an inlet and an outlet, the fluid passage extending through at least part of the length of the rotor; and a ball catch component comprising a receiving end and an interior seat for receiving and retaining a blocking implement, and a fluid passage. When no blocking implement is retained in the rotor assembly, the fluid passage permits flow of drilling fluid entering the receiving end to the fluid passage of the rotor body. The fluid thereby bypasses the motor, which is not activated. When a blocking implement is in place, drilling fluid flows around the ball catch component and into the motor to thereby activate the motor.

A torque transmission comprising input and output shaft adapters. Pins disposed on an outer surface of the input shaft adapter. Each pin provides a curved pin portion oriented generally perpendicular to the input shaft adapter's longitudinal axis. The output shaft adapter provides a recess with a plurality of receptacles (or notches) formed in the recess's periphery, wherein the recess is shaped and sized such that when the input shaft adapter is received inside the recess, each pin is received into a corresponding notch. The torque transmission further comprises torsional bearings interposed between the pins and the notches, each torsional bearing providing a curved laminate portion such that the curved laminate portions contact the curved pin portions when the pins are received into their corresponding notches. The torsional bearings may further provide flat laminate portions that contact the notch when the pins are received into the notches.