A ball screw device includes a screw shaft, a nut, a ball train including a plurality of main balls, and a plurality of coil springs disposed in the ball train. The nut moves from a first axial side to a second axial side while an axial force is applied to the nut by rotation of the screw shaft. The plurality of coil springs are more densely arranged on the first axial side than on the second axial side in the ball train,

A ball screw drive, in particular for a parking brake, comprises a threaded spindle, a spindle nut, and rolling bodies, namely balls, which are arranged in a thread turn between the threaded spindle and the spindle nut. Spring elements are arranged in the thread turn between nut-side stops. There is at least one setting of the threaded spindle and the spindle nut in which the balls and the spring elements are arranged in the thread turn with backlash.

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.

[Problem] To provide a linear motion device using a highly reliable and environmentally friendly separator that improves a dimensional stability, ductility, and adhesion of greases based on poly-?-olefin oil, which are required for separators, and also prevents deformation at high speeds.

[Solution] Provided is a linear motion device including a linear motion body (15) that is fitted onto a screw shaft (11) and moves straight along the screw shaft (11), a large number of balls (B) held in a ball groove (14) formed on an inner surface side of the linear motion body (15) and rolling between the ball groove (14) and the screw shaft (11), a separator (100) interposed 10 between each ball (B), a circulation passage (18) formed in the linear motion body (15) and circulating the ball (B) from one end side of the ball groove (14) to the other end side, where at least one of the separator (100) and the circulation passage (18) is formed from polyamide 410 by injection molding.

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.

A linear motion device includes a linear motion body that is fitted onto a screw shaft and moves straight along the screw shaft, a large number of balls held in a ball groove formed on an inner surface side of the linear motion body and rolling between the ball groove and the screw shaft, a separator interposed between each ball, a circulation passage formed in the linear motion body and circulating the ball from one end side of the ball groove to the other end side, where at least one of the separator and the circulation passage is formed from polyamide 410 by injection molding.