An offset preload ball screw with expandable loading area includes: a screw, a nut, and a plurality of balls between the screw and the nut. The inner helical groove of the nut includes at least a first section, a second section and a third section which are continuously connected one another. The preload constantly and smoothly changes in the second section, and the balls can be subjected to loads in positive or negative direction in the second section. Therefore, the running smoothness, precision and load capacity of the ball screw of the present invention is enhanced.

There is provided a ball screw device capable of allowing interference to be easily elastically deformable and decreasing friction resistance of a seal member with respect to a screw shaft without damaging seal properties of the seal member. A predetermined section of a land sliding-contact portion (46) of a sliding-contact portion (40) and a section of a seal piece (37) of a lip portion (31) corresponding to the predetermined section are bent to protrude in one side in the axial direction of a nut (7) so that a protrusion (55) is formed, the bent section of the land sliding-contact portion (46) and the bent section of the seal piece (37) configure a pair of side surface portions (58, 58) of the protrusion (55) and a bottom portion (61) connecting the one side ends of the pair of side surface portions (58, 58).

An actuator assembly comprises a ball screw drive having a ball screw spindle rotatably mounted about a spindle axis, on which a spindle nut is received, and a thread track on an outer circumferential surface of the ball screw spindle, has a portion of a ball return on a circumferential wall of the ball screw spindle, which return connects a beginning and an end of the thread track to one another. At the beginning and at the end of the thread track, an insert is inserted in which a ball race is formed, which is part of the ball return. The inserts are arranged such that each end of a ball race adjoins a portion of the ball return and another end adjoins a beginning of a thread track or an end of the thread track. In a section perpendicular to a spindle axis, an angle of the ball race to a tangent to the thread track at an adjacent beginning or end of the thread track is greater than 90 in a central portion between the first and the second end of the ball race. To determine the angle, a side of the tangent on which a portion of the thread track directly adjacent to the beginning or the end lies is selected. To produce the ball screw spindle, a channel of the ball return is introduced into the circumferential wall, a thread is introduced into an outer circumferential surface of the ball screw spindle, and in each case one depression is introduced into the outer circumferential surface at the beginning and at the end of the thread track, and inserts are inserted into the depressions.