There provides a ceiling surface of a deflector which secures an allowance for engagement between a rolling ball and a retainer. A ball screw device includes a ball screw shaft, a ball nut, a deflector forming a coupling passage, a rolling ball, and a retainer. The coupling passage is defined by an outer circumferential ball rolling groove, a ridge, and a ceiling surface. The ceiling surface has a first rounded portion at which a projected shape of the ceiling surface seen in an axial direction has a first radius of curvature at least such that a constant first clearance is provided between the rolling ball and the ceiling surface, and a second rounded portion at which the projected shape has a second radius of curvature smaller than the first radius of curvature and which is located on a groove bottom side of the outer circumferential ball rolling groove.

An actuator is provided with means for controlling whether or not forces are transferred between a cylinder 12 (controlled by a motor of the actuator) and an output shaft 14. The output shaft 14 is located between the cylinder 12 and the control rod 18, 38. The cylinder 12 coaxially surrounds the output shaft 14, and the output shaft 14 in turn coaxially surrounds the control rod 18, 38. The control rod 18, 38 has one or more splines 20 on its outer surface facing the output shaft 12. The output shaft 14 has one or more holes 15, each containing a ball bearing 16.

There is provided a dual rack and pinion rotational inerter system for damping movement of a flight control surface of an aircraft. The system has a flexible holding structure disposed between the flight control surface and a support structure of the aircraft. The system has a dual rack and pinion assembly held by and between the flexible holding structure. The dual rack and pinion assembly has a first rack, a second rack, and a pinion engaged to and between the racks. The system has a first terminal coupled to the first rack and coupled to the flight control surface, via a pivot element, and a second terminal coupled to the second rack, and coupled to the support structure. The system has a pair of inertia wheels adjacent the flexible holding structure. The system has an axle element inserted through the inertial wheels, the flexible holding structure, and the pinion.

In a ball screw apparatus, a ball train including a plurality of main balls is housed in a raceway between a ball track of a ball nut and a ball track of a ball screw shaft. A coil spring housed in the raceway includes a first end that engages with an end of the ball train and a second end supported by a stopper (a first recessed portion, a protruding portion, or the like) of the ball nut. A stopper ball having a diameter larger than the diameter of the main ball is interposed between the stopper and the second end of the coil spring.

In a ball screw apparatus, a ball train including a plurality of main balls is housed in a raceway between a ball track of a ball nut and a ball track of a ball screw shaft. A coil spring housed in the raceway includes a first end that engages with an end of the ball train and a second end supported by a stopper (a first recessed portion, a protruding portion, or the like) of the ball nut. A stopper ball having a diameter larger than the diameter of the main ball is interposed between the stopper and the second end of the coil spring.

A threaded drive shaft is provided that has a threaded spindle, a spindle nut, and a spindle disk. The threaded spindle has two different sections with two different outer diameters. The spindle nut is about the larger-diameter portion, such that rotation of the threaded spindle within the spindle nut is allowed. The spindle disk is connected about the smaller-diameter portion of the threaded spindle, and is fixed thereto in a rotationally-fixed manner. The spindle disk has a tapered surface contacting a corresponding tapered surface of the threaded spindle to inhibit rotation. The spindle disk further includes a flange extending from an outer surface thereof that defines a first limit stop surface configured to contact a second limit stop surface of the spindle nut to limit rotation.

A ball screw of an electromechanical brake comprising a ball screw nut disposed on a spindle, wherein the spindle includes complementary tracks formed on the spindle and the ball screw nut. The ball screw further includes a race that includes a plurality of ball pockets spaced apart from one another and a protruding section that includes a concave bearing surface, a ball housed between the concave bearing surface and an end section of a first spring element for a main load direction, and a second spring element for a return stroke direction, wherein the second spring element includes a second spring end section in contact with an opposite side of the bearing surface.

A ball screw apparatus includes a ball nut through which a ball screw shaft is inserted. A recessed portion is formed in an inner periphery of the ball nut and is recessed so as to extend in a tangential direction of a ball track. A ball train including a plurality of main balls and a coil spring are housed in a raceway. The recessed portion includes a first surface that supports a second end of the coil spring via a stopper ball and a second surface that regulates movement of the stopper ball in a nut axial direction. The second surface is inclined by an angle corresponding to a lead angle of the ball track of the ball nut from an axially perpendicular plane of the ball nut so as extend in the direction of the lead angle.

A motion guide device includes a ball nut attached onto a shaft and having helical grooves for receiving ball bearing elements, a ball circulating member is engaged with the ball nut and includes a ball circulating channel communicative with the helical groove of the ball nut, and includes an intermediate segment and two end segments, a ball coupler includes two flexible coupling members for engaging with the ball bearing elements, and the ball circulating member includes two opposite helical guide pathways for receiving the flexible coupling members of the ball coupler, and curved relative to the ball circulating member for smoothly guiding the flexible coupling members to move through the ball circulating member.

A rolling device includes: an inner member that has a raceway face; an outer member that has a raceway face facing the raceway face; and rolling elements that are disposed between both raceway faces in a rollable manner, wherein at least one of the inner member and the outer member has a space formed therein. Further, a method for manufacturing a rolling device including an inner member that has a raceway face, an outer member that has a raceway face facing the raceway face, rolling elements that are disposed between both raceway faces in a rollable manner, and a space that is formed inside at least one of the inner member and the outer member by a 3D printer.