Provided is a turning function-equipped having a reduced size and having improved strength to an external shock force and improved reliability. The turning function-equipped hub unit includes: a hub unit main body; a unit support member; and a turning actuator. The unit support member is provided to a chassis frame component. The unit support member includes an abutment part with which a part of the hub unit main body is brought into abutment in a vertical direction during non-normal time, the abutment part being separated from the hub unit main body in the vertical direction during normal time, and the non-normal time in which the abutment is caused, is a time when an impact load equal to or greater than a predetermined value acts on the hub unit main body in the vertical direction due to an external force from the wheel.

A wheel steering device for a vehicle, including: a steering knuckle that constitutes a part of a suspension device and that is capable of moving relative to a body of the vehicle in an up-down direction, the steering knuckle holding a wheel such that the wheel is rotatable; and a steering actuator configured to cause the steering knuckle to be pivoted about a kingpin axis so steer the wheel, wherein a caster angle and a caster offset are both 0.

A planetary roller screw drive for an actuator of a rear-axle steering system of a motor vehicle, including a planetary roller support which accommodates the planetary rollers and is connected to a drive sleeve for rotation therewith, which drive sleeve is driven rotatably about the screw spindle and is mounted rotatably on a machine part by an axial angular contact roller bearing which is arranged coaxially with respect to the drive sleeve and of which the rollers are in rolling contact with angled-bearing raceways which are inclined with respect to a plane arranged transversely with respect to the axis of rotation of the drive sleeve.

An electric power steering apparatus having independent turning mechanisms for respective four wheels of a vehicle, has a problem in that, when a turning motor fails, a turning mechanism for a corresponding wheel stops functioning, resulting in reduction in the maneuverability and the stability of the vehicle. Turning motors of turning mechanisms independently disposed for respective four wheels of a vehicle, each have a redundant configuration. Specifically, each turning motor is configured as three-phase duplexing motors having two three-phase windings and two inverters for separately driving the three-phase windings.

A work vehicle steering control apparatus comprises a vehicle body (11), front wheels and rear wheels both of which can be steered respectively; a front-wheel steering cylinder (92) and a rear-wheel steering cylinder (94); a steering dial (72); a steering actuation controller (50); and a steering angle detector. The steering actuation controller (50) is configured in a manner such that when a steering operation is performed, and when the steering angles of one set of wheels are less than a predetermined angle (θ.sub.1), the controller (50) controls the steering actuator to steer only the one set of wheels in response to the directional-change steering operation. When the steering angles of the one set of wheels are equal to or more than the predetermined angle, the controller (50) controls the steering actuator to steer the other set of wheels in a direction opposite to steering direction.

Provided is an electric power steering device including: a front-wheel steering mechanism, which is provided to front wheels of a vehicle, and includes a front-wheel steering motor as a drive source; and a rear-wheel steering mechanism, which is provided to rear wheels of the vehicle, and includes a rear-wheel steering motor as a drive source, wherein the rear-wheel steering motor is configured to be a double-inverter three-phase duplex motor, the double-inverter three-phase duplex motor including two three-phase windings and two inverters each configured to individually drive one of the two three-phase windings. Therefore, the electric power steering device is capable of, even when a failure has occurred in the steering motor of the rear-wheel steering mechanism, maintaining a function of the rear-wheel steering mechanism to secure behavior stability of the vehicle.

An all-wheel steering system for a motor vehicle is described which has an active front axle steering system and an active rear axle steering system. The front axle steering system includes a gear ratio unit which is coupled to a steering wheel. The gear ratio unit is configured to define a front axle steering angle as a function of a steering wheel angle and a front axle steering ratio. In addition, the gear ratio unit is coupled to the rear axle steering system in such a way that the front axle steering ratio is adjustable as a function of a rear axle steering angle. Further, a motor vehicle having such an all-wheel steering system is discussed. Also presented is a method of operating an all-wheel steering system for a motor vehicle.

A dual-mode active rear-wheel steering device based on a multi-linkage mechanism, including: a steering angle control motor with a speed-reduction mechanism, a multi-linkage mechanism assembly for converting rotational motion of the steering angle control motor into linear motion of an end of the push rod, a steering actuating mechanism for converting linear motion of the multi-linkage mechanism assembly into rotation of a knuckle around a kingpin to make the rear wheels steer, a first electromagnetic pin puller and a second electromagnetic pin puller respectively configured to control a first extendable-retractable push rod assembly and a second extendable-retractable push rod assembly to work at a fixed or variable axial length. The device uses the steering angle control motor to drive the two rear wheels to turn in the same direction or opposite directions through the control of energized state of the two electromagnetic pin pullers.

A dual-mode active rear-wheel steering device, including: a steering angle control motor, a speed-reduction mechanism, a differential mechanism assembly, two steering motion conversion mechanisms, a first electromagnetic clutch and a second electromagnetic clutch. An output end of the steering angle control motor is connected to the speed-reduction mechanism. The differential mechanism assembly is a bevel gear differential, in which center holes at outer ends a two half shafts are respectively provided with a raceway to form an inner cyclical ball-lead screw-nut pair with a first lead screw and a second lead screw of the steering motion conversion mechanisms. The first lead screw and the second lead screw are the same in parameters but with opposite rotation direction. The first electromagnetic clutch controls connection between a differential housing and a frame. The second electromagnetic clutch controls connection between the differential housing and the second half shaft.

A rear wheel steering apparatus may include: a driving part housed in a housing part; a rotating part rotated by the driving part; a moving shaft part connected to tie rods, and screwed to the rotating part; a spline plate spline-coupled to the moving shaft part so as to restrict rotation of the moving shaft part; and a space maintaining part protruding from the moving shaft part or the spline plate, and maintaining a space between the moving shaft part and the spline plate.