The invention relates to a ball screw (10) with a threaded spindle (12), a nut (14), rolling bodies (16) and at least one deflecting device (18, 20), wherein the threaded spindle (12) is displaceable by rotation, and wherein the deflecting device comprises an inner first body part (18) and an outer second body part (20), which body parts together form a deflecting channel (22), wherein the deflecting channel (22) has two tubular ends (24, 26) which are connected to each other via a transfer region (28), wherein the tubular ends (24, 26) of the deflecting channel are in each case formed by mutually complementary partial tubular sections (30, 32, 34, 36) of the body parts (18, 20), and wherein a sleeve (40) surrounding the nut (14) is provided, the deflecting device (18, 20) sits in an opening (42) in the nut (14), the deflecting device (18, 20) projects radially beyond the outer lateral surface of the nut (14) in a relaxed state when the sleeve (40) is absent and, in the presence of the sleeve (40), said sleeve exerts a radially inwardly directed force on the deflecting device (18, 20).

The linear actuator comprises elongated first and second bands that cooperate to form an extractable and retractable column. Rotatable first and second band guide members respectively guide turns of the first and second bands into intertwined engagement. A power actuator causes rotation of the first and second band guide members such that the extractable and retractable column may be extracted or retracted. A base carries the power actuator, the first and second bands and the first and second band guide members. An anti-rotation mechanism comprises a first anti-rotation member attached to the base and a complementary second anti-rotation member attached to at least one of the first and second bands, with the first and second anti-rotation members engaging one another in the column to prevent rotation of the column relative to the base. The engagement of the first and second anti-rotation members is non-punctual about a periphery of the column.

The linear actuator comprises elongated first and second bands that cooperate to form an extractable and retractable column. Rotatable first and second band guide members respectively guide turns of the first and second bands into intertwined engagement. A power actuator causes rotation of the first and second band guide members such that the extractable and retractable column may be extracted or retracted. A base carries the power actuator, the first and second bands and the first and second band guide members. An anti-rotation mechanism comprises a first anti-rotation member attached to the base and a complementary second anti-rotation member attached to at least one of the first and second bands, with the first and second anti-rotation members engaging one another in the column to prevent rotation of the column relative to the base. The engagement of the first and second anti-rotation members is non-punctual about a periphery of the column.

In a worm, a cutting start part forming one end part of a tooth bottom part is provided at a first tapered part. A cutting end part forming another end part of the tooth bottom part is provided at a second tapered part. The tooth bottom part extends to advance in a spiral shape from the cutting start part toward one circumferential side (counterclockwise direction) of the worm. A position of the cutting end part is configured within an angle range (at a position of 38 degrees) of less than 90 degrees on another circumferential side (clockwise direction) of the worm with respect to a position of the cutting start part, centered on a rotation center (equal to a rotation center of a rotating shaft) of the worm.