A downhole motor having an improved thread fastening structure is proposed. In the downhole motor, a thread structure disposed therein and having ridges formed at both end portions at a predetermined distance from ends is improved and the internal structures of a first coupler and a second coupler in which the end portions of the thread are respectively inserted and fastened are improved to correspond to the end portions of the thread, thereby being able to improve sealing ability.

A downhole motor having an improved thread fastening structure is proposed. In the downhole motor, a thread structure disposed therein and having ridges formed at both end portions at a predetermined distance from ends is improved and the internal structures of a first coupler and a second coupler in which the end portions of the thread are respectively inserted and fastened are improved to correspond to the end portions of the thread, thereby being able to improve sealing ability.

An apparatus in the form of an adapter for forming a connection comprising a first part adapted for coupling with a second part by a quick-release coupling formed by a first projection of the first part having an at least partial dovetail shape and a recess of the second part having an at least partial dovetail shape. An opening in the recess is adapted for receiving the projection in an axial direction. In other embodiments, the adapter is: (1) frictionally enhanced for engaging an internal portion of the drilling element; (2) includes a radial projection elongated in an axial direction for engaging the internal portion of the one drilling element; and/or (3) has a cutter for scoring an internal portion of the one drilling element upon being inserted therein and rotated. An adapter is also disclosed for use with a drill chuck, including for creating a twist lock connection.

An apparatus in the form of an adapter for forming a connection comprising a first part adapted for coupling with a second part by a quick-release coupling formed by a first projection of the first part having an at least partial dovetail shape and a recess of the second part having an at least partial dovetail shape. An opening in the recess is adapted for receiving the projection in an axial direction. In other embodiments, the adapter is: (1) frictionally enhanced for engaging an internal portion of the drilling element; (2) includes a radial projection elongated in an axial direction for engaging the internal portion of the one drilling element; and/or (3) has a cutter for scoring an internal portion of the one drilling element upon being inserted therein and rotated. An adapter is also disclosed for use with a drill chuck, including for creating a twist lock connection.

A spindle assembly for connecting a drill string to a rotational drive for use in a horizontal directional drilling operation. The assembly comprises a saver sub attached to the rotational drive, and a drive chuck for connection to the drill string. The drive chuck and saver sub form a torque-transmitting connection by engaging through a seat in the saver sub and an engagement point on the drive chuck. Dowel pins may be used to rotationally lock and provide the engagement between the saver sub and the drive chuck. A collar may thread to the saver sub and cause an interference fit by engaging the drive chuck at a shoulder.

A spindle assembly for connecting a drill string to a rotational drive for use in a horizontal directional drilling operation. The assembly comprises a saver sub attached to the rotational drive, and a drive chuck for connection to the drill string. The drive chuck and saver sub form a torque-transmitting connection by engaging through a seat in the saver sub and an engagement point on the drive chuck. Dowel pins may be used to rotationally lock and provide the engagement between the saver sub and the drive chuck. A collar may thread to the saver sub and cause an interference fit by engaging the drive chuck at a shoulder.

A drive unit includes a drive stem having first friction surfaces and a load coupling, wherein the load coupling is a threaded coupling. The drive unit also includes a transmission unit having second friction surfaces parallel to the first friction surfaces; and shoulders proximate a bottom of the transmission unit. The drive unit further includes a transmission selector movable to an on position or an off position, wherein the drive stem moves synchronously with the transmission unit when the transmission selector is in the on position.

A device for earth or rock drilling has a mast, a drill drive with a shaft for rotatably driving a drill rod, a drill drive carriage, on which the drill drive is arranged, movably supported along the mast, and an oscillation generating drive disposed behind the drill drive in a drilling direction connected to the drill rod for transmitting an oscillation. A rear connecting end of the shaft or the drill rod projects rearwards from the drill drive. A rotary coupling with a first coupling piece is provided on the connecting end in an axially fixed and torque-proof manner, and a second coupling piece is axially fixed and rotatable relative to the first coupling piece. The oscillation drive has a clamping means for releasably clamping the second coupling piece, such that in the clamped state an axially fixed connection is formed between the oscillation drive and the second coupling piece.

A device for earth or rock drilling has a mast, a drill drive with a shaft for rotatably driving a drill rod, a drill drive carriage, on which the drill drive is arranged, movably supported along the mast, and an oscillation generating drive disposed behind the drill drive in a drilling direction connected to the drill rod for transmitting an oscillation. A rear connecting end of the shaft or the drill rod projects rearwards from the drill drive. A rotary coupling with a first coupling piece is provided on the connecting end in an axially fixed and torque-proof manner, and a second coupling piece is axially fixed and rotatable relative to the first coupling piece. The oscillation drive has a clamping means for releasably clamping the second coupling piece, such that in the clamped state an axially fixed connection is formed between the oscillation drive and the second coupling piece.

A rotary percussive hydraulic drill comprises a body; a shank having female coupling splines and male coupling splines; a striking piston configured to strike the shank; a rotation drive device configured to drive the shank in rotation; a front abutment surface against which the shank is configured to come into abutment. The shank has an annular bearing flange which is provided on an outer surface of the shank and which has an annular bearing surface configured to come into abutment against the front abutment surface. Each of the female and male coupling splines provided on the shank extends from the annular bearing flange in the direction of the striking piston, wherein a connecting surface of each female coupling spline provided on the shank being at least in part formed by a curved concave surface extending substantially in an extension direction of the respective female coupling spline and having a radius of curvature which is less than a radial height of each of the male coupling splines provided on the shank.