A hydraulic steering unit includes a pressure port connected to a main flow path and a tank port connected to a tank flow path, and a working port arrangement having left and right working flow paths. A first bridge arrangement has first left and first right orifices connected to the main flow path and to first left or first right connecting points, respectively, each connecting point associated respectively with the left or right working flow paths, and second left and second right orifices connected to the tank flow path and to the first left or first right connecting points, respectively. A second bridge arrangement has a similar orifice arrangement connected to second left or second right connecting points. The first and second bridge arrangements have different steering characteristics. Selection means for connecting one of the bridge arrangements between the pressure port and the working port arrangement are provided.

A hydraulic steering unit includes a pressure port connected to a main flow path and a tank port connected to a tank flow path, and a working port arrangement having left and right working flow paths. A first bridge arrangement has first left and first right orifices connected to the main flow path and to first left or first right connecting points, respectively, each connecting point associated respectively with the left or right working flow paths, and second left and second right orifices connected to the tank flow path and to the first left or first right connecting points, respectively. A second bridge arrangement has a similar orifice arrangement connected to second left or second right connecting points. The first and second bridge arrangements have different steering characteristics. Selection means for connecting one of the bridge arrangements between the pressure port and the working port arrangement are provided.

A steering system of a vehicle is provided. The steering system adjusts the torsional rigidity of a torsion bar without limitation as to the configuration thereof and performs active control responding to the vehicle state by adjusting steering characteristics by controlling the torsional rigidity of the torsion bar based on the traveling condition, load state or driving mode of the vehicle. The steering system includes an MR assist device, which is coupled to an end portion of the torsion bar and adjusts the rotation and torsional rigidity of the torsion bar using an MR fluid as a working fluid.

A steering system of a vehicle is provided. The steering system adjusts the torsional rigidity of a torsion bar without limitation as to the configuration thereof and performs active control responding to the vehicle state by adjusting steering characteristics by controlling the torsional rigidity of the torsion bar based on the traveling condition, load state or driving mode of the vehicle. The steering system includes an MR assist device, which is coupled to an end portion of the torsion bar and adjusts the rotation and torsional rigidity of the torsion bar using an MR fluid as a working fluid.

A hydraulic system for a working machine includes a first electric machine connected to a first hydraulic machine; a second electric machine connected to a second hydraulic machine, an output side of the second hydraulic machine being connected to an input side of the first hydraulic machine; at least one hydraulic consumer hydraulically coupled to an output side of the first hydraulic machine via a supply line and configured to be powered by the first hydraulic machine; and a valve arrangement arranged between the hydraulic consumer and the first and second hydraulic machines, wherein the valve arrangement is configured to control a return flow of hydraulic fluid from the hydraulic consumer to either the input side of the first hydraulic machine or an input side of the second hydraulic machine based on a requested output pressure from the first hydraulic machine.

A system and method for detecting the functional state of a piloted or direct-operated isolation valve in a hydraulic circuit is presented. In some examples the hydraulic circuit is a steering circuit and the isolation valve provides selective isolation between a hydraulic actuator and one or more metering valves. In some examples, the isolation valve assembly is movable between a first position, in which fluid flow between the metering valve and the actuator is enabled, and a second position, in which fluid flow between the metering valve and the actuator is blocked. When the isolation valve assembly is moved to one of the first and second positions, an inlet port and a pressure sensing port of the isolation valve assembly are placed in fluid communication with each other. When the isolation valve assembly is moved to the other of the first or second position, a second inlet port and the pressure sensing port are placed in fluid communication.

A system and method for detecting the functional state of a piloted or direct-operated isolation valve in a hydraulic circuit is presented. In some examples the hydraulic circuit is a steering circuit and the isolation valve provides selective isolation between a hydraulic actuator and one or more metering valves. In some examples, the isolation valve assembly is movable between a first position, in which fluid flow between the metering valve and the actuator is enabled, and a second position, in which fluid flow between the metering valve and the actuator is blocked. When the isolation valve assembly is moved to one of the first and second positions, an inlet port and a pressure sensing port of the isolation valve assembly are placed in fluid communication with each other. When the isolation valve assembly is moved to the other of the first or second position, a second inlet port and the pressure sensing port are placed in fluid communication.

An improved power steering assembly is provided. The power steering assembly includes an end-of-travel mechanism and a valve cartridge that is actuated by left and right actuator rings of the end-of-travel mechanism, the actuator rings extending partially around an output shaft. The actuator rings can be individually set for the desired end-of-travel relief to limit the maximum system pressure when the steering assembly approaches the desired axle stop setting. The valve cartridge provides an end-of-travel function and a pressure relief function and is in fluid communication with the left and right pressure chambers to recirculate hydraulic fluid in the event of a power off condition.

A driver assistance system for a vehicle includes a steering assistance system for autonomously generating steering commands, a first actuating drive for adjusting a steering angle on a steerable wheel of the vehicle corresponding to the steering commands and a steering wheel that is rotatable coupled to the steering angle by a second actuating drive. The steering assistance system actuates the second actuating drive in order to favor a low-frequency component of a frequency spectrum of changes of the steering angle in the rotation of the steering wheel than a high-frequency component of the frequency spectrum.

A hydraulic circuit, in particular to a hydraulic steering circuit for steering at least one vehicle axle, the hydraulic circuit including a first fluid path having a first end and a second end and providing fluid communication or selective fluid communication between the first end and the second end of the first fluid path; and a second fluid path providing fluid communication or selective fluid communication between the first end of the first fluid path and the second end (2) of the first fluid path, in parallel to the first fluid path or to a section thereof. In some aspects, the first fluid path includes a first hydraulic displacement unit; and the second fluid path includes at least a first proportional bypass control valve for controlling a bypass fluid flow in the second fluid path. The hydraulic steering circuit may be part of a driveline for a vehicle.