Abstract: A hydraulic steering arrangement 1 is described comprising a supply port arrangement having a pressure port (4) and a tank port (5), a working port arrangement having two working ports (6, 7), a steering unit (2) arranged in a flow path (9) between the supply port arrangement (4, 5) and the working port arrangement (6, 7), and a second flow path (13) in form of an amplification flow path bridging the steering unit (2) and having an amplification orifice (AU1) which is controlled as function of the steering unit (2). Such a steering arrangement should have a possibility to change the steering behaviour. To this end at least a third flow path (14) in form of an amplification flow path is arranged in parallel to the second flow path (13), wherein the second/or the third flow path (13, 14) comprise an valve (15).

Abstract: A work vehicle includes a wheel supporting member 11 that is supported by a vehicle body frame 1 that includes left and right side members 80; left and right steerable wheels that are supported by the wheel supporting member 11 so as to be steerable; and a steering mechanism 25 that includes a power steering unit 24 and steers the left and right steerable wheels. The power steering unit 24 is located near the wheel supporting member 11 such that at least a portion of the power steering unit 24 is located between the left and right side members 80.

Abstract: An active steering system using planetary gear set with less tooth difference and a control method thereof. The system includes a first input shaft with one end connected to a steering wheel of an automobile and the other end fixedly sleeved with a first gear; a ring gear sleeve, where a ring gear is fixedly mounted in the ring gear sleeve circumferentially, and a hollow shaft protrudes from a center of an end of the ring gear sleeve and is fixedly sleeved with a second gear engaged with the first gear; a second input shaft with one end fixedly connected to an output end of a coupled motor and the other end fixedly sleeved with a third gear; an eccentric shaft with one end fixedly sleeved with a fourth gear engaged with the third gear and the other end sleeved in the hollow shaft and eccentrically provided with a boss.

Abstract: A hydraulic unit for supplying pressure to a hydraulic steering system is provided having at least two hydraulic cylinders and at least one hydraulic pump (9, 10, 32, 33). It is essential that the hydraulic cylinders are of interacting configuration, by an annular space (6a, 6a, 28a, 28b) of the first hydraulic cylinder being connected via at least one hydraulic line to an annular space (6a, 6a, 28a, 28b) of the second hydraulic cylinder, and a piston space (5a, 5b, 29a, 29b) of the first hydraulic cylinder being connected via at least one hydraulic line to a piston space (5a, 5b, 29a, 29b) of the second hydraulic cylinder, and a hydraulic pump (9, 10, 32, 33) being arranged at least in a hydraulic line (7, 8, 30, 31) between the two annular spaces (6a, 6a, 28a, 28b) or in a hydraulic line (7, 8, 30, 31) between the two piston spaces (5a, 5b, 29a, 29b). Furthermore, the invention relates to methods for operating a hydraulic unit for supplying pressure to a hydraulic steering system, and to a steering system.

Abstract: A steering system includes a drag link having a first support bushing opposite a second support bushing, a first steering hydraulic cylinder operably connected to the drag link, a second steering hydraulic cylinder operably connected to the drag link, a first tie rod operably connected to the drag link, and a second tie rod operably connected to the drag link. Each of the first and second cylinders and first and second tie rods are arranged to apply a corresponding radial force that is distributed between the first and second support bushings. One or more of the first and second steering cylinders and/or the first and second tie rods is positioned relative to the drag link to minimize a net summation of the first and second cylinder radial forces and the first and second tie rod radial forces that are applied to the first and second support bushings.

Abstract: A trailering assist system for a vehicle includes a camera disposed at a vehicle, with the camera having a field of view rearward of the vehicle that encompasses a trailer that is being towed by the vehicle. The camera is operable to capture image data. A control of the system includes an image processor operable to process captured image data. Responsive to input of vehicle parameters and processing of captured image data by the image processor, the trailering assist system is operable to determine an estimated trailer angle and an estimated vehicle steering wheel angle. The control compares the estimated vehicle steering wheel angle to a measured or determined or actual vehicle steering wheel angle to determine an error value. The control is operable to generate an output when the error value is at or above a threshold level.

Abstract: A steering mechanism and guidance system for a milling attachment device provides steering capability without impeding cutting depth control. The steering mechanism has at least one wheel that is rotated by an actuating mechanism such as an extending cylinder, synchronized actuators, or the like. The steering mechanism may be integrated with depth control by using a parallelogrammic structure with pivot points to assist in the depth control or may operate independent of and without impeding depth control.

Abstract: An automatic transmission includes a mechanical oil pump, an electric oil pump, and a controller. The controller calculates a flow rate of oil necessary for the automatic transmission during the vehicle travels, and drives the electric oil pump when the calculated flow rate of the oil necessary for the automatic transmission is higher than a margin flow rate of the mechanical oil pump generated in a state where a hydraulic pressure necessary for the automatic transmission is ensured.

Abstract: A hydraulic system is provided for a steering system of a vehicle. The hydraulic system includes a pump that supplies pressurized fluid during an operation of the steering system. The hydraulic system also includes an accumulator that is in independent and selective communication with each of the pump and the steering system. When the pump is in the operational state to support the operation of the steering system, some of the fluid may be routed into the accumulator and stored in the accumulator for later use. In the event of failure of the pump when the steering system is in operation, the accumulator provides the required amount of fluid to continue operation of the steering system until charge in the accumulator depletes to a value that is no longer sufficient to support operation of the steering system.

Abstract: The present disclosure relates to a hydraulic system for construction equipment, and more particularly, to a hydraulic system, in which an actuator is controlled by a pump/motor. The hydraulic system for construction equipment according to the present disclosure includes logic valves in first and second hydraulic lines provided to an actuator, respectively, and when it is desired to operate the actuator in a state where an operation of the actuator is stopped by closing the logic valves, a pressure difference may be resolved by increasing pressure in sections of a pump/motor and the logic valves in advance even if a load is applied to the actuator, and thus the actuator may implement a desired operation without being affected by the load. That is, it is possible to improve operation controllability of the actuator.

Abstract: The present disclosure relates to a hydraulic system for a construction machine which uses an electric hydraulic pump, and more particularly, to a hydraulic system including an emergency control unit for temporarily driving the construction machine when an electronic control unit controlling the electric hydraulic pumps fails to operate.

Abstract: In a control apparatus for a hydraulic power steering system including multiple electric pumps, a first ECU determines that start-up of a first motor is completed when a first current value, which is a value of current flowing to a first electric pump, has been within a prescribed current range continuously for a prescribed period of time or longer. An upper limit of the prescribed current range is set to be less than to a limit value provided as an upper limit of a current supplied simultaneously to the first and second electric pumps after completion of start-up. A lower limit of the prescribed current range is set to a minimum value of a current indicating that the first electric pump is in an energized state. After start-up of the first motor is determined to be completed, a second ECU starts electric power supply to the second electric pump.

Abstract: A refrigeration system includes a medium temperature subsystem circulating a coolant in a closed loop between at least one medium temperature chiller and at least one medium temperature load and at least one cascade heat exchanger, and a low temperature subsystem circulating a coolant in a closed loop between at least one low temperature heat exchanger and at least one low temperature load. A cooling circuit is provided for circulating a coolant and includes a first pump and a second pump and a fluid cooler and a valve, and interfaces with the medium temperature chiller and the low temperature chiller. The valve is movable to a closed position to define a first flow path and a second flow path, where the first flow path includes the first pump and the medium temperature chiller and fluid cooler, and the second flow path including the second pump and the low temperature heat exchanger and the cascade heat exchanger.

Abstract: A steering arrangement including a first, second, third and fourth hydraulic chamber, the first and third chambers being operable to steer in a first direction and the second and fourth chambers being operable to steer in a second direction. A pump system supplies fluid to a steering system, which is operable to supply the pressurised fluid to one or more of the first, second, third and fourth hydraulic chambers. The steering system having a first mode wherein fluid is supplied to the first and third hydraulic chambers to steer in the first direction, or pressurised fluid is supplied to the second and fourth hydraulic chambers to steer in the second direction. The steering system having a second mode to steer in the first direction, or to steer in the second direction, such that the steering ratio is higher in the second mode than in the first mode.

Abstract: A power steering apparatus including a power cylinder, first and second pumps, a control valve serving for selectively supplying a working fluid supplied from the first or second pump to one of a pair of pressure chambers of the power cylinder in accordance with a steering operation, first and second reservoir tanks, and a return passage changeover valve disposed between the control valve and the first and second pumps, the return passage changeover valve serving for communicating the first and second pumps with the control valve regardless of an axial position of a valve element and communicating one of the first and second reservoir tanks with the control valve in accordance with the axial position of the valve element to thereby carry out changeover between circulating fluid passages for circulating the working fluid to the first reservoir tank and the second reservoir tank.

Abstract: A hydraulic power steering system controllable by left and right steering wheels has two control valves, each valve connected to a respective left and right steering wheel, and a valve arrangement that selectively connects one control valve to a source of high-pressure fluid and disconnects the other control valve from the source of high-pressure fluid.

Abstract: An electric motor system that triggers brake and steering function upon engine failure featuring an electric motor; and a vacuum pump, an oil pump, and a sensor each operatively connected to the electric motor. The vacuum pump is connected to the vehicle's brake servo and the oil pump is connected to an oil reservoir and to the vehicle's steering sector. The sensor is adapted to detect when the engine is turned off. When the engine is turned off the sensor is activated and causes activation of the electric motor. Activation of the electric motor causes activation of the vacuum pump and the oil pump. The vacuum pump functions to provide a vacuum in the servo brake of the vehicle and the oil pump functions to create oil pressure with oil in the oil reservoir and direct oil pressure to the steering sector.

Abstract: The present disclosure relates to construction machinery such as an excavator or a wheel loader, and more particularly, to an emergency steering apparatus for construction machinery, capable of controlling a steering operation at the time of emergency in which a part of equipment malfunctions or is in an inoperable state. More specifically, an emergency steering apparatus for construction machinery according to an exemplary embodiment of the present disclosure includes: a steering actuator; an emergency hydraulic pump connected to the steering actuator through a pair of driving flow paths; an emergency steering unit configured to receive working oil, which is discharged from the emergency hydraulic pump, and operate a steering means; and an emergency steering controller configured to control whether or not the emergency hydraulic pump is operated.

Abstract: A steering system includes a steer-by-wire (SBW) valve, a main steering pump, a steering actuator, and a steering control unit (SCU). The SCU is in fluid communication with the actuator via a pair of fluid conduits, and includes upper and lower portions. The upper portion contains a first solenoid valve and a cross-over check valve assembly. The lower portion contains a fluid control valve. An ECU generates a steering input signal in response to steering wheel rotation, and transmits the signal to the SBW valve. The SCU controls the first solenoid valve to deliver fluid from the lower portion to the actuator via the cross-over valve assembly in an emergency steering mode, and also controls the first solenoid valve to prevent flow into the actuator and allow recirculation of fluid within the lower portion in a torque feel mode.

Abstract: In a method for reducing the rollover risk in vehicles, at least one state variable which characterizes the transverse dynamics of the vehicle is ascertained and is used as the basis for an intervention into the steering system and the braking system which stabilizes the vehicle. A multivariable control is carried out in which two control loops are superimposed, the first control loop being based on control of the yaw rate and the second control loop being based on control of the transverse acceleration. The steering system as well as the braking system may be adjusted via the first and second control loops.

Abstract: A vehicle by-wire steering system includes a hydraulic default level. A hydraulic feed unit and a hydraulic actuating unit can be connected together by two hydraulic lines such that when an actuator is non-functional, a steering wheel rotational angle is transformed into a corresponding wheel steering angle by the hydraulic feed unit and the hydraulic actuating unit. The hydraulic lines can be connected together by a switchable steering valve, which is designed as a proportional servo valve, of which the flow cross section can be adjusted in essence continuously between the two extremes of completely closed and completely open.

Abstract: A steering system, comprising: an input cylinder having a first hydraulic chamber and a second hydraulic chamber; a transmission mechanism, wherein a transmission efficiency for converting and transmitting a linear motion of the input cylinder to a rotary motion of a steering wheel is less than a transmission efficiency for converting and transmitting the rotary motion of the steering wheel to the linear motion of the input cylinder; an output cylinder connected to a steerable vehicle wheel and having a third hydraulic chamber and a fourth hydraulic chamber; a first hydraulic passage for connecting the first hydraulic chamber to the third hydraulic chamber; a second hydraulic passage for connecting the second hydraulic chamber to the fourth hydraulic chamber; a flow rate control mechanism for exchanging hydraulic oil with: a first hydraulic circuit including the first and third hydraulic chambers and the first hydraulic passage; and a second hydraulic circuit including the second and fourth hydraulic chambers

Abstract: A steering system is provided for controlling the turning angle of the steering wheels of a vehicle. The steering system includes two electro-hydraulic circuits each including an actuator, both actuators being mechanically coupled and acting simultaneously on the turning angle of the wheels. A first circuit is displacement-controlled relative to a position set point while a second circuit is stress controlled. The set point applied of the second circuit includes a component developed from the filtering of the position set point applied to the first circuit.

Abstract: A hydraulic power steering system for a vehicle, e.g., an electrohydraulic power steering system for a motor vehicle, includes a servo valve, the relative movement of whose control parts actuates a piston rod of a servo cylinder and changes at least one steering angle of a wheel which is operatively connected to the piston rod, and additionally has an electric servo motor which drives a rack with the servo cylinder for adjusting the steering angle of the wheel in the same direction. In order to provide an electrohydraulic power steering system which is as compactly arranged as possible in the region of its actuator and may be used flexibly for different classes of vehicle, the action of the rack and the piston rod of the servo cylinder is combined, in a parallel arrangement with one another, on an addition member for jointly adjusting the steering angle of the wheel.

Abstract: A hydraulic steering system (1) including a hydraulic steering unit (2) and an auxiliary device (3). Said The steering unit (2) feeds a hydraulic medium to a steering cylinder (5) according to the movement of a steering wheel (4). The auxiliary device (3) includes a valve unit (6) and also feeds a hydraulic medium to the steering cylinder (5) according to the movement of the steering wheel (4), in order to assist the steering movement. The hydraulic medium ejected or discharged from the steering cylinder (5) as a result of the hydraulic medium fed thereinto flows back into a tank (10) or to a pump (8, 9) through the steering unit (2).

Abstract: The invention relates to a steering device for vehicles with a double-acting hydraulic working cylinder, which is divided into two working chambers by a piston, which is displaceably mounted in the working cylinder, to pivot at least one vehicle wheel, and a pressurizing means device producing a volume flow of a hydraulic medium, the hydraulic medium being supplied to a rotary slide valve, which supplies the volume flow, depending on the rotary slide valve position, to the working chambers of the double-acting hydraulic working cylinder or to a reservoir for the hydraulic medium, wherein when a certain pressure is exceeded in the feed line to the rotary slide valve, a pressure relief valve guides at least a part of the total volume flow of the hydraulic medium past the rotary slide valve in particular to the reservoir.

Abstract: A steering system with reduced coupling between a position overlay unit and a torque overlay unit may include a remote valve assembly for controlling a hydraulic assist force or an electric motor for providing torque overlay and electric assist to a rack of a rack and pinion steering system. In one embodiment, the position overlay unit may provide the assist force and the torque overlay unit may provide a motor command signal to the motor of a differential positioned on a steering shaft. In another embodiment, the position overlay unit may provide the motor command signal and the torque overlay unit may provide the assist force. In either embodiment, the position overlay unit may include variable ratio gain that uses a position signal to output a variable ratio command.

Abstract: A power steering apparatus (10) includes a first pump (24) which is continuously driven to supply fluid under pressure to a power steering motor assembly (18). A second pump (32) is driven by the engine (30) of the vehicle when a predetermined vehicle operating condition occurs. The predetermined vehicle operating condition may, if desired, be operation of the engine (30) of a vehicle at a speed which is less than a predetermined speed. A flow control valve (40) directs fluid flow from the first and second pumps to the power steering motor assembly (18) during operation of both pumps. A diverter valve (62) directs fluid from the first pump (24) along a fluid flow path which is spaced from the flow control valve (40) during operation of only the first pump. The first pump (24) may, if desired, be smaller than the second pump (32).

Abstract: A vehicle steer by wire system which has a steering wheel for setting a desired turn angle of a vehicle wheel, a steering wheel turn sensor for sensing the desired turn angle, a hydraulic steering actuator for turning the wheel, a wheel turn sensor for sensing the current wheel turn angle and a control unit for receiving the desired turn angle and current wheel turn angle signals. An electronically controlled steering actuator control valve means is provided for supplying pressurized fluid to the steering actuator via a steering circuit in response to signals from the control unit to turn the wheel to the desired turn angle. A hydraulic motor connected with the steering wheel is provided to provide steering feedback to the steering wheel via a feedback circuit which includes an electrically controlled hydraulic feedback control valve means which directs fluid to and from the hydraulic motor in response to the signals from the control unit to generate the steering feedback.

Abstract: A variable gear ratio hydraulic power steering device 1 is provided with a variable ratio transmission mechanism 7 for varying the rotation transmission ratio between the rotational angle of a steering handle 31 and the rotational angle of a pinion shaft 33 and a flow volume control valve 40 for controlling the discharge flow volume of an oil pump 10 which circulates operating fluid. The variable ratio transmission mechanism 7 has a lock mechanism 75. A valve controlling controller 50 for controlling the flow volume control valve 40 switches main and secondary flow volume control maps for controlling the flow volume control valve 40, in dependence on the operational state of the lock mechanism 75. Thus, a failsafe function for the variable ratio transmission mechanism 7 is given to the variable gear ratio hydraulic power steering device 1.

Abstract: In a power steering device comprising a power steering pump, and to a method for operating a power steering device for a vehicle comprising a hydraulic circuit provided with a rotary slide valve, a steering cylinder and a control valve for adjusting the volume flow of a hydraulic medium as required for steering assistance, the control valve is arranged on the pressure side of the pump in such a way that it divides the volume flow (Q) from the power steering pump into at least a first base partial flow (A) and a second controlled partial flow (B), the base partial flow (A) being independent from the operating state of the control valve and always available for steering assistance, whereas the partial flow (B) is dependent on the operating state of the control valve.

Abstract: A steering system, e.g., a hydraulic rack and pinion steering system for motor vehicles, includes a steering handle for prescribing a steering intention, a pressure medium source and a control valve device for controlling a flow of pressure medium to and from a servomotor in order to deflect vehicle wheels. The control valve device has a closed center, and a pressure medium accumulator is provided for producing and/or assisting a flow of pressure medium to and from the servomotor.

Abstract: The invention relates to a device and a method to ensure the steerability of an industrial truck that has a hydraulic steering system. The invention includes at least one gas generation cartridge (8) and a device (16) to activate the generation of the gas. The invention teaches that energy is available in an emergency for the hydraulic circuit of a hydraulic steering system. On the side of the gas generation cartridge (8), when there is a need to supply energy to the hydraulic circuit, pressure is increased which can then be transmitted to the hydraulic medium. The invention makes available an advantageous emergency power supply system for a hydraulic steering system of an industrial truck.

Abstract: A steering system functions in accordance with the “steer by wire” concept and has a normal operating system without positive coupling between the steering handle and the steered vehicle wheels, as well as an emergency operating system, which functions with positive coupling between the steered vehicle wheels and the steering handle. An auxiliary operating system is additionally provided, which, in response to malfunctions of the normal operating system, assumes its tasks and, in a transitional phase, adapts the performance characteristics of the steering system to those of the emergency system, which is switched on upon conclusion of the transitional phase. Thus, at the transition from the normal operating system to the emergency operating system, the driver is given time to become accustomed to the other steering performance.

Abstract: A hydraulic steering system (1) for a vehicle with two steering motor arrangements, particularly an articulated vehicle with wheel steering, with a hydraulic steering unit (2) having a measuring motor section (22, 23), with a selection valve (6), which connects an outlet (L, R) of the steering unit (2) with either a first steering motor arrangement (7) that preferably acts upon steered wheels, or a second steering motor arrangement (9) that preferably acts upon a converting kit, and which is hydraulically operable via a pilot valve (14), and with a pump (4), which is connected with the steering unit (2) and the pilot valve (14). This permits the vehicle to be steerable in connection with an emergency.

Abstract: A hydraulic steering arrangement with a steering handwheel which is connected with a hydraulic steering unit, and with a steering motor connected with a pump via a steering valve. In a steering arrangement of this kind, a simple construction is desired, though under maintenance of the required security. For this purpose, the steering valve can optionally be operated by a steering handwheel or by a hydraulic pressure generated by a control pressure generator.

Abstract: A transmission mechanism and a pressure oil supply system therefor are provided for use in work vehicles provided with a work device externally of the body of the vehicle at longitudinal one side thereof, the transmission mechanism being simple in construction and serving to shorten the overall length of the vehicle while holding a transmission shaft interconnecting a PTO shaft and an input shaft for the work device close to a horizontal. A work vehicle provided with a work device in front of the vehicle body comprises a transmission 30 disposed between a differential gear unit 10 and an HST 20 and providing a travel cooperative mechanism, a PTO shaft projecting from the housing of the HST 20, and a PTO cooperative mechanism disposed in the housing for dividedly deriving power for the PTO shaft from the travel cooperative mechanism for the transmission of the power.

Abstract: An automotive steer-by-wire system is disclosed that includes a first network. The first network connects a first set of controllers for controlling a first set of motors. The steer-by-wire system further includes a second network that is independent of the first network and connects a second set of controllers for controlling a second set of motors. The steer-by-wire system includes a third network that connects the first set of controllers and the second set of controllers for controlling the first or second set of motors if the first or second network is inoperative, whereby information is transmitted via the third network independent of the first network and the second network.

Abstract: An abnormality detection circuit for detecting abnormality of a CPU includes a command value check circuit for checking whether a current command value calculated by the CPU is normal or abnormal with respect to a torque signal, and a drive signal check circuit for checking whether a motor drive signal outputted based on the current command value is normal or abnormal. When the command value abnormality of the CPU is detected by the abnormality detection circuit, a counter circuit is started to count a time of an abnormality state of the CPU. If the counted time reaches a predetermined time, a control stop command is outputted from a system stop circuit to the CPU, thereby stopping the system control of the CPU.

Abstract: The invention relates to a vehicle steering system comprising a steering linkage, a control hydraulic motor and a control hydraulic circuit, a steering wheel connected to the control hydraulic motor, and a control hydraulic cylinder connected to the control hydraulic motor by the control hydraulic circuit. The vehicle steering system further comprises a servohydraulic cylinder, a servopump, a servohydraulic circuit connecting the servopump to the servohydraulic cylinder, and an electronic control circuit which controls the servohydraulic circuit.

Abstract: A steer-by-wire steering system for steering a set of road wheels is disclosed. The system comprises a controller and at least one actuator assembly connected to the controller and to the at least one wheel of the set of road wheels. The at least one actuator assembly comprises an electro-mechanical actuator connected to the controller, a crank arm connected to the electro-mechanical actuator, a steering arm connected to the at least one wheel of the set of road wheels; and a tie rod having a first end thereof connected to the crank arm and a second end thereof connected to the steering arm. The electro-mechanical actuator, in response to a signal from the controller, is operative to rotate the crank arm producing thereby a force acting through the tie rod so as to rotate the steering arm and the at least one road wheel to a desired position. The steer-by-wire steering system includes a backup system capable of assuming operative command of the steer-by-wire steering system.

Abstract: In a power steering system having hydraulic power support for motor vehicles, a steering gear shaft having a steering wheel is connected to an input element of a steering gear. An output element of the steering gear is connected to wheels of the vehicle to be steered. Two working chambers of a servo motor of a power boosting system can be supplied with a hydraulic medium from a servo pump through a steering valve in accordance with a torque applied in the area of the steering gear shaft input element. Two sensors for detecting an angle of rotation and a torque are provided on the steering gear shaft and on the output element of the steering gear accordingly. After the steering wheel has been released after a steering operation, the wheels to be steered and the steering gear can be returned with hydraulic support. Both the intensity and direction of the hydraulic power support as well as the returning of the wheels to be steered are controlled by a common, electronically controlled electromagnetic valve.

Abstract: A hydrostatic steering arrangement with two control systems, each of which has a control unit with an inner and an outer rotary slide and a steering motor, one steering handwheel being common for both control units, and the control units being arranged in series in the axial direction of the rotary slides. On a failure of one control unit it is desired that the steering can be continued with a relatively high accuracy. For this purpose, a common inner rotary slide is provided for both control units.

Abstract: A steering device for self-propelled working machines. Steering cylinders are associated with each pair of wheels and a fluid which is suppliable from a valve unit to the cylinders. At least one hydraulic pump is connected to the valve unit via hydraulic lines, and the valve unit includes a respective switching unit (16, 19) incorporating on-off valves (24, 25, 25′) associated with each steering cylinder (8, 9). In the event of a fault, the on-off valves (24, 25, 25′) are automatically switchable in a manner such that the steering cylinders (8, 9) can be controlled by a single steering control unit (18).

Abstract: A steering system for motor vehicles, in which a steering member or steering wheel and the steered vehicle wheels are hydraulically positively coupled for the steering actuation of the wheels. An additional servo system is provided which is responsive to torque transmitted between the steering wheel and master unit of the hydraulic system.

Abstract: A hydraulic power steering system for non-tracked vehicles, particularly motor vehicles, has a steering adjustment of the steered vehicle wheels which takes place of a hydraulic actuating assembly which can be connected by a change-over valve with one respectively of two or several hydraulic circuits. In normal operation, the circuits operate in parallel and functionally in the same direction so that, in the event of a disturbance, a change-over can take place to another hydraulic circuit without any interruption. For controlling the actuating assembly, each hydraulic circuit comprises a servo valve which is operated as a function of a desired-actual value comparison of the steering angle by a control and automatic control device, which is connected with an actual steering angle value generator operated by the steered vehicle wheels and a desired steering angle value generator controlled by way of the steering handle operated on the driver side.

Abstract: A steering system is provided for motor vehicles, in which, during the normal operation, the driver adjusts an actual steering angle value generator by way of a steering handle. A control and automatic control arrangement correspondingly operates the steered vehicle wheels by a motor-operated adjusting assembly. For an emergency, a forced coupling is provided between the steering handle and the steered vehicle wheels which switches on automatically. This forced coupling is constructed such that a centering mode can be switched on, during which, when the forced coupling is at least partially switched off, the manual steering wheel can be adjusted until a position is reached. Thereby, in the straight-ahead position of the steered vehicle wheels, the manual steering wheel takes up a defined normal position.

Abstract: A way is provided to simulate the steering handle manual torques which correspond to a steering stop of the steered vehicle wheels for a vehicle steering system which can be operated in a normal mode and in an emergency mode. The steering system is capable of being switched between a steer-by-wire level assigned to the normal mode, on which level a steering handle is connected to steered vehicle wheels via an electric or electronic control system, and a fall-back level assigned to the emergency mode, on which level the steering handle is positively coupled mechanically and/or hydraulically to the steered vehicle wheels. The fall-back level is activated in normal mode if the steered vehicle wheels are displaced into the region of the steering stop.

Abstract: High functional reliability for a vehicle steering system that can be switched between a normal mode with a steer-by-wire level and an emergency mode with a fall-back level is achieved by providing that the fall-back level has a hydraulic system which contains a manual-side double-acting piston-cylinder unit which is actuated with a steering handle, e.g. steering wheel. The unit is positively coupled hydraulically to a wheel-side double-acting piston-cylinder unit which actuates steered vehicle wheels. A hydraulic charging system has a hydraulic pump, the inlet side of which is connected to a hydraulic-fluid reservoir. Switchable hydraulic couplings are provided for hydraulically coupling and decoupling the hydraulic system of the fall-back level and the hydraulic charging system to and from one another, respectively.

Abstract: A steering system of a non-track-bound motor vehicle having steered vehicle wheels which are operatively connected to a steering handle in normal operation only via an electronic regulating arrangement which checks itself continuously for correct operation. In a manner dependent on a desired-value transmitter actuated by the steering handle and on an actual-value transmitter actuated by way of the vehicle wheels, this regulating arrangement actuates an actuating drive for the steering displacement of the steered vehicle wheels. If the regulating arrangement malfunctions, a positive coupling between the steering handle and the steered vehicle wheels is automatically activated. This also occurs if a characteristic variable correlated with the desired/actual value deviation of the steering angle is outside tolerance thresholds.