A ball screw device is provided, including a retainer that can properly retain balls. The difference between a diameter being the pitch circle diameter of the ball screw device and the outside diameter of the rack shaft is set to be equal to or larger than the difference between the bore diameter of a ball screw nut and the diameter. The thickness center diameter of the retainer is set to be smaller than the diameter. Even when the inclination angle is reduced, the clearance between the inclined surfaces of each retainer groove on the radial inside can be easily set to be smaller than the diameter of the balls because the bore diameter of the retainer is set to be smaller. Thus, even when the inclination angle of the inclined surfaces is set to be smaller, the balls can be properly retained.

A rotary hydraulic actuator may be configured to output rotary motion to control a hinged surface of an aircraft. The actuator includes a nested ballscrew, ballnut, and output assembly that form concentric ball races for converting the linear motion and force of the linear actuator to rotary motion and torque of the output assembly that is connected to the hinged surface. One of the ball races is helically inclined and the other of the ball races is linear. The rotary hydraulic actuator may include a ball return structure that returns the balls from a loaded path of a ball race to an unloaded path of the ball race. The ball return structure may define a ball return path that is located at the same radial distance from the actuator centerline as the loaded path for minimizing the overall diameter of the actuator.

A ball screw nut having a tubular sheet metal body with a thread profile and being optionally encapsulated in plastic. This sheet metal body is formed of a sheet metal part that includes the thread profile and a ball-returning piece inserted therein, which is designed as an additional sheet metal part.

A threaded nut for a ball screw drive is provided. The threaded nut includes a cylindrical central piece ending at a flange. A deflecting body is attached to the cylindrical central piece and is configured to recirculate balls during operation of the threaded nut. A pin fixes the deflecting body to the flange. In embodiments, the flange and the deflecting body each have recesses that are aligned with one another, and the pin extends through those recesses.

In a multi-piece deflector for a ball screw mechanism, the positioning precision of a tongue with respect to a ball rolling passage can be improved, balls can be recirculated in a proper manner at all times, and damages to the tongue can be avoided. A deflector main body (40) which is fitted to the nut (7) is provided with a tongue (50) and a main body side ball guide groove (51) defining a part of a circular cross section, and a component piece (60) which is fitted to the deflector main body (40) is provided with a component piece side ball guide groove (68) defining a remaining part of the circular cross section.

A linear transmission device includes a screw, a moving member, a return element, and a sensor. The moving member is set in the screw to form a load path therebetween. The return element is set in the moving member and has a return path connected to the load path. The return path and the load path constitute a circulating path for balls to run. The moving member has an internal thread with an ineffective thread section. The moving member has a receiving groove adjacent to the ineffective thread section. The sensor is embedded in the receiving groove of the moving member without affecting the operation of the balls. Thus, the linear transmission device of the present invention can solve the problem of the sensor protruding from the moving member, so that the configuration of the surrounding space and the stroke of the moving member will not be affected.

A ball screw drive with a spindle nut (1) arranged on a screw spindle (2) and a continuous ball channel (7) formed by the screw spindle (2) and the spindle nut (1), in which channel balls arranged along a continuous ball track (8) circulate continuously, wherein the continuous ball channel (7) includes a load channel (9) wound in a spiral shape, with more than one winding, about a spindle axis (S) and a deflecting channel (10) which continuously connects the two ends of the load channel (9) to one another, wherein the spindle nut (1) has a nut part (4), on the inner circumference of which a ball groove (6) is formed being wound in a spiral shape about the spindle axis S, which ball groove, together with a ball groove (3) of the screw spindle (2) being wound in a spiral shape about the spindle axis S, forms the load channel (9), and wherein a deflecting element (5) including the deflecting channel (10) is arranged on the outer periphery of the nut part (4), and the deflecting ends (12) of the deflecting element (5) axially spaced apart from one another each penetrate a recess (11) through the thickness of the wall of the nut part (4), in order to deflect balls from the load channel (9) into the deflecting channel (10), and wherein the recess (11) has an unloading bore (15) connecting to the ball groove (6) of the nut part (4) and to the deflecting end (12) of the deflecting element (5) for unloading the balls, the axis of which unloading hole is arranged at a parallel distance to a plane (E1) containing the spindle axis (S).

An object of the present invention is to preferably detect the failure accompanied with the decrease in the pre-load in a ball screw unit. The failure diagnosis is performed for the ball screw unit on the basis of a combination of a resonance frequency in an axial direction of a predetermined machine assembly including the ball screw unit and a motor and a position of a nut member on a screw shaft corresponding to the resonance frequency as provided when the screw shaft is driven and rotated by the motor.

A motion conversion mechanism includes a shaft having an external thread and a cylinder having an internal thread that is screwed with the external thread. The motion conversion mechanism converts rotating motion of one of the shaft and the cylinder into linear motion of the other of the shaft and the cylinder. The cylinder is provided with two internal thread portions, each having the internal thread, such that a threadless portion is interposed between the two internal thread portions in an axial direction.

A ball screw in a steering system has a groove between the inner peripheral surface of a cylindrical ball nut through which a steered shaft extends and the outer peripheral surface of the steered shaft, and balls are accommodated in the groove. The balls rolling and flowing in the groove are returned from downstream to upstream via deflectors and a return passage member disposed in the ball nut. The return passage member has a first connection portion curved to connect one end of a linear portion of the return passage member to the first deflector, and a second connection portion curved to connect the other end of the linear portion to the second deflector. Each connection portion has an opening that opens in the return passage member longitudinal end face and an opening that opens in the return passage member outer periphery of toward the centerline of the ball nut.