Abstract: A constant-velocity joint can have three pieces: a yoke, a first adaptor, and a second adaptor. Grooves on opposite sides of the yoke can receive forks of the adaptors and be perpendicular to one another. The yoke can have a guide surface within each groove so that a matching following surface on the fork of the adaptor can engage the guide surface to guide the movement of the fork within the groove. The adaptors may pivot within the grooves such that surfaces of flanks of the forks remain engaged or provide a consistent amount of surface contact with flanks of the groove throughout the pivot of the forks. Torque can be transferred through the engaged flanks as the joint is used to convert eccentric rotation to concentric rotation.

Abstract: A downhole tool having a mechanically adjustable bend angle from the surface and method for actuation of the tool. The tool includes a knuckled joint between upper and lower housing assemblies and tapered setting ring upon which the lower housing assembly bears. As the setting ring is rotated with respect to the upper housing assembly, the lower assembly is tilted. A spline sub for connection to a drill string is included, which, upon a certain weigh on bit, axially moves within the tool housing to engage the tapered setting ring and force shoes radially outward to engage the formation and hold the tool stationary. The drill string is then rotated to rotate the setting ring, and thereby alter the tool bend angle. Toggles hold the setting ring fixed to the upper housing to maintain a given bend angle during drilling operations.

Abstract: An example downhole motor may include a first housing and a second housing with first and second portions characterized by non-parallel longitudinal axes. The second housing may be rotatably coupled to the first housing, and the first portion of the second housing may be arranged in a fixed, non-parallel longitudinal orientation with the first housing. A drive shaft may be at least partially within the first housing, and the motor may further comprise a selectively engageable torque coupling between the drive shaft and the second housing, positioned within the first housing.

Abstract: A rotational anchor mechanism is mounted on an operatively nonrotating housing that forms part of a drill string. An anchor linkage forming part of the anchor mechanism is radially extendable and contractible to move an anchor member, such as a roller, mounted on the anchor linkage radially towards and away from the housing, to engage a borehole wall for resisting rotation of the housing relative to drill pipe that is drivingly rotated within the housing. The anchor linkage includes operatively coupled mounting links mounted on the housing to pivot about respective mounting axes which are parallel to one another in a fixed spatial relationship. An actuating mechanism is coupled to the anchor linkage to exert an actuating force on the anchor linkage. An angular orientation of the actuating force relative to the housing varies in response to variation in radial expansion of the anchor linkage.

Abstract: A constant-velocity joint can have three pieces: a yoke, a first adaptor, and a second adaptor. Grooves on opposite sides of the yoke can receive forks of the adaptors and be perpendicular to one another. The yoke can have a guide surface within each groove so that a matching following surface on the fork of the adaptor can engage the guide surface to guide the movement of the fork within the groove. The adaptors may pivot within the grooves such that surfaces of flanks of the forks remain engaged or provide a consistent amount of surface contact with flanks of the groove throughout the pivot of the forks. Torque can be transferred through the engaged flanks as the joint is used to convert eccentric rotation to concentric rotation.

Abstract: An example downhole motor may include a first housing and a second housing with first and second portions characterized by non-parallel longitudinal axes. The second housing may be rotatably coupled to the first housing, and the first portion of the second housing may be arranged in a fixed, non-parallel longitudinal orientation with the first housing. A drive shaft may be at least partially within the first housing, and the motor may further comprise a selectively engageable torque coupling between the drive shaft and the second housing, positioned within the first housing.

Abstract: A downhole tool having a mechanically adjustable bend angle from the surface and method for actuation of the tool. The tool includes a knuckled joint between upper and lower housing assemblies and tapered setting ring upon which the lower housing assembly bears. As the setting ring is rotated with respect to the upper housing assembly, the lower assembly is tilted. A spline sub for connection to a drill string is included, which, upon a certain weigh on bit, axially moves within the tool housing to engage the tapered setting ring and force shoes radially outward to engage the formation and hold the tool stationary. The drill string is then rotated to rotate the setting ring, and thereby alter the tool bend angle. Toggles hold the setting ring fixed to the upper housing to maintain a given bend angle during drilling operations.

Abstract: A rotational anchor mechanism is mounted on an operatively nonrotating housing that forms part of a drill string. An anchor linkage forming part of the anchor mechanism is radially extendable and contractible to move an anchor member, such as a roller, mounted on the anchor linkage radially towards and away from the housing, to engage a borehole wall for resisting rotation of the housing relative to drill pipe that is drivingly rotated within the housing. The anchor linkage includes operatively coupled mounting links mounted on the housing to pivot about respective mounting axes which are parallel to one another in a fixed spatial relationship. An actuating mechanism is coupled to the anchor linkage to exert an actuating force on the anchor linkage. An angular orientation of the actuating force relative to the housing varies in response to variation in radial expansion of the anchor linkage.

Abstract: The subject matter of this specification can be embodied in, among other things, a locking clutch that includes a collection of movable locking blocks slidably coupled to the rotatable output shaft. The movable locking blocks slide radially inwardly and outwardly with respect to a central longitudinal axis of the rotatable output shaft, and are spaced apart circumferentially about the rotatable output shaft, with each movable locking block having a first contacting face and a second contacting face. A collection of fixed locking blocks are coupled to the rotatable housing, and are positioned radially around the output shaft and spaced apart circumferentially about the interior of the rotatable housing a distance sufficient to receive one of the movable locking blocks when it moves inwardly toward the central axis of the rotatable output shaft, each said fixed locking block having a first contacting face and a second contacting face.

Abstract: The subject matter of this specification can be embodied in, among other things, a locking clutch that includes a collection of movable locking blocks slidably coupled to the rotatable output shaft. The movable locking blocks slide radially inwardly and outwardly with respect to a central longitudinal axis of the rotatable output shaft, and are spaced apart circumferentially about the rotatable output shaft, with each movable locking block having a first contacting face and a second contacting face. A collection of fixed locking blocks are coupled to the rotatable housing, and are positioned radially around the output shaft and spaced apart circumferentially about the interior of the rotatable housing a distance sufficient to receive one of the movable locking blocks when it moves inwardly toward the central axis of the rotatable output shaft, each said fixed locking block having a first contacting face and a second contacting face.

Abstract: The subject matter of this specification can be embodied in, among other things, a method that includes a downhole rotational lock mechanism including a tubular housing having a longitudinal bore with an internal wall. A driving gear is disposed in the longitudinal bore of the tubular housing and has a peripheral edge secured to the internal wall of the longitudinal bore of the tubular housing. The driving gear has an upper portion including a plurality of gear teeth arranged around a central longitudinal bore through the driving gear. A driven gear is movably disposed in the longitudinal bore of the tubular housing, and has a central longitudinal bore and a lower portion including a plurality of gear teeth. An output drive shaft is disposed longitudinally in the longitudinal bore of the tubular housing and in the longitudinal bore of the driven gear.

Abstract: The subject matter of this specification can be embodied in, among other things, a method that includes a downhole rotational lock mechanism including a tubular housing having a longitudinal bore with an internal wall. A driving gear is disposed in the longitudinal bore of the tubular housing and has a peripheral edge secured to the internal wall of the longitudinal bore of the tubular housing. The driving gear has an upper portion including a plurality of gear teeth arranged around a central longitudinal bore through the driving gear. A driven gear is movably disposed in the longitudinal bore of the tubular housing, and has a central longitudinal bore and a lower portion including a plurality of gear teeth. An output drive shaft is disposed longitudinally in the longitudinal bore of the tubular housing and in the longitudinal bore of the driven gear.