In one aspect of the invention, a torsion bar assembly is provided. The assembly includes a first shaft having a first bore, a second shaft having a second bore, the second shaft operatively coupled to the first shaft, and a torsion bar positioned within the first and second bores. The torsion bar includes a splined first end having a first diameter extending to a first end face having a diameter generally the same as the first diameter, a splined second end having a second diameter extending to a second end face having a diameter generally the same as the second diameter, and an active diameter extending between the splined first end and the splined second end. The torsion bar is fabricated from a material having a hardness greater than 45 Rockwell C-Scale.

In one aspect of the invention, a torsion bar assembly is provided. The assembly includes a first shaft having a first bore, a second shaft having a second bore, the second shaft operatively coupled to the first shaft, and a torsion bar positioned within the first and second bores. The torsion bar includes a splined first end having a first diameter extending to a first end face having a diameter generally the same as the first diameter, a splined second end having a second diameter extending to a second end face having a diameter generally the same as the second diameter, and an active diameter extending between the splined first end and the splined second end. The torsion bar is fabricated from a material having a hardness greater than 45 Rockwell C-Scale.

An articulated work vehicle with linked front and rear frames includes a hydraulic actuator, a joystick lever operated by an operator, a control valve, a force imparting component, and a controller. The hydraulic actuator is driven hydraulically to change a steering angle of the front frame with respect to the rear frame. The control valve is linked to the joystick lever, to control flow of fluid supplied to the hydraulic actuator according to an operation amount of the joystick lever, and to restrict the operation amount of the joystick lever to a predetermined range. The force imparting component imparts an assist force or a counterforce to the operation of the joystick lever by the operator. The controller controls the force imparting component so as to decrease the assist force or increase the counterforce before the operation of the joystick lever is restricted by the control valve.

A power steering apparatus includes a steering shaft 10 including an input shaft 11, an intermediate shaft 13 connected through a first torsion bar 12 to the input shaft, and an output shaft 15 connected through a second torsion bar 14 to the intermediate shaft; a hollow motor 30 to provide a rotational force to the intermediate shaft; and a control device 60 including a microcomputer, and including an output shaft rotation angle presuming section 63 to presume an output shaft rotation angle g based on signals of an input shaft rotation angle h and an intermediate shaft rotation angle m, a torsion spring constant g1 and g2 of the first and second torsion bars; and a motor drive control section 69 to control the hollow motor based on the output shaft rotation angle.

A power steering apparatus includes a steering shaft 10 including an input shaft 11, an intermediate shaft 13 connected through a first torsion bar 12 to the input shaft, and an output shaft 15 connected through a second torsion bar 14 to the intermediate shaft; a hollow motor 30 to provide a rotational force to the intermediate shaft; and a control device 60 including a microcomputer, and including an output shaft rotation angle presuming section 63 to presume an output shaft rotation angle g based on signals of an input shaft rotation angle h and an intermediate shaft rotation angle m, a torsion spring constant g1 and g2 of the first and second torsion bars; and a motor drive control section 69 to control the hollow motor based on the output shaft rotation angle.

In one aspect of the invention, a retainer assembly for a power steering assist system is provided. The retainer assembly includes a retainer having an inner wall defining an opening, at least one permanent magnet coupled to the retainer, and at least one spiral channel formed in the inner wall.

A steering shaft for a motor vehicle steering system may be used in connection with a variety of power assistance mechanisms. The steering shaft may comprise a first shaft part and a second shaft part that are rotationally-elastically coupled by way of a torsion bar. In order to transmit torque, the torsion bar may be received in a bore of the first shaft part and coupled to both the first and second shaft parts. In many cases, a first end of the torsion bar is coupled to the first shaft part, and a second end of the torsion bar is coupled to the second shaft part. The torsion bar may be mounted in the bore such that it can be rotated with respect to the first shaft part via a bearing element. In some examples, the bearing element comprises a prestressing element.

A steering shaft for a motor vehicle steering system may be used in connection with a variety of power assistance mechanisms. The steering shaft may comprise a first shaft part and a second shaft part that are rotationally-elastically coupled by way of a torsion bar. In order to transmit torque, the torsion bar may be received in a bore of the first shaft part and coupled to both the first and second shaft parts. In many cases, a first end of the torsion bar is coupled to the first shaft part, and a second end of the torsion bar is coupled to the second shaft part. The torsion bar may be mounted in the bore such that it can be rotated with respect to the first shaft part via a bearing element. In some examples, the bearing element comprises a prestressing element.

A hydraulic steering unit (1) is described comprising a supply port arrangement having a pressure port (P) connected to a main flow path (5) and a tank port (T) connected to a tank flow path (6), a working port arrangement having a left working port (L) connected to a left working flow path (7) and a right working port (R) connected to a right working flow path (8), a bridge arrangement (14) of variable neutral open orifices, said bridge arrangement (14) comprising a first left orifice (A2L) connected to a main flow path (5) and to the left working flow path (7), a first right orifice (A2R) connected to a main flow path (5) and to the right working flow path (8), a second left orifice (A3L) connected to the left working flow path (7) and to the tank flow path (6), and a second right orifice (A3R) connected to the right working flow path (8) and to the tank flow path (6). Such a steering unit has a good steering behavior but can function as a closed-center solution. To this end a further variable orifice arrangement is arranged between the supply port (P) arrangement and the working port arrangement (T), which further orifice arrangement is closed in neutral position.

A steering device includes: a steering shaft; a transmitting mechanism configured to transmit the rotation of the steering shaft to a steered wheel; a power cylinder; a rotary valve configured to selectively supply a hydraulic fluid to the pair of the fluid chambers in accordance with the rotation of the steering shaft; and an electric motor configured to provide a rotation force through a speed reduction device to the steering shaft, the steering shaft including a first shaft connected to the steering wheel, and a second shaft connected to the first shaft, and configured to output the rotation force inputted from the first shaft, to the transmitting mechanism side, and the electric motor being connected through the speed reduction device to the second shaft.