A spindle drive (20) for an actuator of a steer-by-wire steering system (10). The spindle drive has a linearly displaceable threaded spindle (27). The spindle drive (20) is in the form of a roller screw drive. The roller screw drive has a first efficiency in the driving direction and a second different efficiency in the reverse-driving direction.

A load sensor to be used in an electromechanical brake system includes a flange member capable of deflecting when receiving, at a load receiving portion, a load from the axially front side; a support member capable of supporting the flange member from the axially rear side, at a support portion displaced from the load receiving portion in a radial direction orthogonal to the axial direction; and a displacement detecting mechanism configured to detect the amount of relative movement between the flange and support members. A variable detection sensitivity mechanism enables the relative movement amount with respect to the change of the load applied to the flange member to be larger in a low load range in which the load is equal to or lower than a predetermined load value than in a high load range in which the load is higher than the predetermined load value.

A spindle drive (20) for an actuator of a steer-by-wire steering system (10). The spindle drive has a linearly displaceable threaded spindle (27). The spindle drive (20) is in the form of a roller screw drive. The roller screw drive has a firs efficiency in the driving direction and a second different efficiency in the reverse-driving direction.

A load sensor used in an electromechanical brake system is provided. The load sensor includes a flange member capable of deflecting when receiving, at a load receiving portion, a load from the axially front side; a support member capable of supporting the flange member from the axially rear side, at a support portion displaced from the load receiving portion in a radial direction orthogonal to the axial direction; a displacement detecting mechanism configured to detect the amount of relative movement between the flange and support members; and a variable detection sensitivity mechanism enabling the relative movement amount with respect to the change of the load applied to the flange member to be larger in a low load range in which the load is equal to or lower than a predetermined load value than in a high load range in which the load is higher than the predetermined load value.

An electric linear motion actuator includes an outer ring member provided around a central shaft, and planetary rollers disposed between the central shaft and the outer ring member. One of the central shaft and the outer ring member serves as an input member which is rotatable and immovable in the axial direction and rotated by an electric motor, while the other serves as an output member which is rotationally stationary and movable in the axial direction. The input member has a peripheral surface formed with a plurality of annular ribs which are equal in pitch. Each planetary roller has a radially outer surface formed with annular grooves which are equal in pitch to the annular ribs and in which the annular ribs are engaged. The output member has a peripheral surface formed with a helical rib which is equal in pitch to the annular grooves of the planetary rollers.

A roller screw drive, in particular in the form of a planetary roller gear, a roller screw drive or an inverse roller screw drive, including a threaded spindle with an external thread, a plurality of planets, and a spindle nut with an internal profile. Each planet has a profiled central section, which engages in the external thread of the spindle nut, and two equally profiled side sections which are thinner than the central section, which side sections each mesh with a section of the internal profile of the spindle nut. End sections of each planet adjoining the side sections are held in recesses of separate guide discs. Each recess for holding the planet has an assembly holding contour and an operating holding contour separated therefrom.