An apparatus for boring a wellbore, including a bit body having a first end, an inner cavity, and a second end. The first end is connected to a workstring that is configured to deliver a rotational force to the bit body. The inner cavity contains a profile having a first radial cam surface. The second end includes a working face containing a cutting member. The apparatus also includes a pilot bit rotatively connected within the inner cavity. A second radial cam surface is contained on a first end of the pilot bit. The first and second radial cam surfaces are operatively configured to deliver a hammering force. A second end of the pilot bit may include an engaging surface configured to engage a formation surrounding the wellbore. The bit body rotates relative to the pilot bit.

A telescopic actuator having a linear movement is disclosed including a motor for applying a drive torque to a screw drive, such that a threaded spindle can be linearly extended or retracted with respect to a screw nut. The telescopic actuator includes four screw drives and extends or retracts on both sides in the axial direction, the total extension path being composed of four partial extension paths.

A system for inhibiting no-back brake device creep includes a motor, a ballscrew assembly coupled to the motor, a no-back brake device coupled to the ballscrew assembly, and at least one damper coupled to the ballscrew assembly. The damper varies a damping characteristic based on an operational state of the motor.

An actuating device having a longitudinal shaft, an internal sleeve, an external sleeve, internal screw connecting means provided between the longitudinal shaft and the intermediate sleeve, external screw connecting means provided between the intermediate sleeve and the external sleeve. The direct efficiency of the internal screw connecting means is higher than the direct efficiency of the external screw connecting means. The self-releasable coupling means are provided between the longitudinal shaft and the internal sleeve.

A valve device includes a control device adapted to control a valve without being supplied with electricity. The control device includes at least one rotatable control cam having an outer periphery with a concave and convex shape, and a driving device adapted to rotate the control cam only in a first rotational direction, out of the first rotational direction and a second rotational direction opposite from the first rotational direction, by being supplied with a pressurized medium. The valve is placed such that a switch portion comes in contact with the outer peripheral portion of the control cam, in order that the valve is opened and closed by the control cam being rotated.

A valve device includes a control device adapted to control a valve without being supplied with electricity. The control device includes at least one rotatable control cam having an outer periphery with a concave and convex shape, and a driving device adapted to rotate the control cam only in a first rotational direction, out of the first rotational direction and a second rotational direction opposite from the first rotational direction, by being supplied with a pressurized medium. The valve is placed such that a switch portion comes in contact with the outer peripheral portion of the control cam, in order that the valve is opened and closed by the control cam being rotated.

A linear actuator comprises a roller screw mechanism guided in rotation with respect to a structure by two angular-contact ball bearings, the roller screw mechanism comprising rollers interposed between an endless screw and two tapped rings which are joined together in rotation and free in translation. Each tapped ring is secured to an inner ring of a ball bearing. The linear actuator further comprises a single preloading device capable of applying load between two outer rings of the angular-contact ball bearings respectively, thereby simultaneously allowing the loading of the roller screw mechanism and the rotational guidance of the roller screw mechanism with respect to the structure.

A secondary drive coupling may comprise at least one coupling member having a first mating portion and a second mating portion. The first mating portion is configured to engage a first section of a shaft on one side of a region of weakness of the shaft, whereas the second mating portion is configured to engage a second section of the shaft on an axially opposite side of the region of weakness. Both the first mating portion and the second mating portion are each configured to prevent rotation of the at least one coupling member about the shaft. In another embodiment, the at least one coupling member comprises a first coupling member comprising the first mating portion and a first contact surface and a separate, second coupling member comprising a second mating portion and a second contact surface that is configured to engage the first contact surface.

A method for designing a spline surface contour of a roller-type wave-motion includes of the steps of slicing radial movement track of a roller between a cam and a spline aperture and circumference rotation track at equal proportion at equal time intervals to sequentially obtain circle centers and points of tangency of the track circles during movement of the roller; connecting the points of tangency to form a unit cam circumference segment of a cam periphery in order to draw and form a single-sided tooth flank contour; and forming a correspondent side tooth flank contour by mirroring and projecting the single-sided tooth flank contour. A method of forming a spline wheel contour and a method of forming a cam periphery are obtained.

A method for designing a spline surface contour of a roller-type wave-motion includes of the steps of slicing radial movement track of a roller between a cam and a spline aperture and circumference rotation track at equal proportion at equal time intervals to sequentially obtain circle centers and points of tangency of the track circles during movement of the roller; connecting the points of tangency to form a unit cam circumference segment of a cam periphery in order to draw and form a single-sided tooth flank contour; and forming a correspondent side tooth flank contour by mirroring and projecting the single-sided tooth flank contour. A method of forming a spline wheel contour and a method of forming a cam periphery are obtained.