Abstract: A power steering system includes: a first drain passage for draining an oil pressure from a first oil passage, a second drain passage for draining the oil pressure from a second oil passage, and a pair of a first and second switch valves. When one of the first oil passage and the second oil passage is so pressurized by an operation of a reversible oil pump as to have an increased internal pressure, the pair of the first switch valve and the second switch valve allow the following: i) closing one of the first drain passage and the second drain passage which one is connected to the oil passage having the thus increased internal pressure, while ii) opening the other of the first drain passage and the second drain passage which other is connected to the oil passage that is so depressurized as to have a decreased internal pressure.

Abstract: An integral power steering apparatus includes a stroke limiter. A piston defines two hydraulic chambers in a housing. A communicating passage, a first valve disposed between the first hydraulic chamber and the communicating passage, and a second valve disposed between the second hydraulic chamber and the communicating passage, are provided to serve for a stroke limiter, in addition to a hydraulic circuit for supplying hydraulic fluid to the two hydraulic chambers. The two valves each include a valve body having a bore and serving as a valve seat, a plunger slidably fitted within the bore of the valve body and serving as a valving element, and a spring disposed on the bottom of the bore of the valve body and biasing the plunger to be in contact with the valve body.

Abstract: The invention relates to a hydraulically supported steering system with a steering gear, which is driven by a hydraulic piston/cylinder unit. The steering system includes a piston. The piston is axially displaced in a cylinder and divides the cylinder into two cylinder chambers. Each cylinder chamber is connected to a separate hydraulic line that serves both as pressure supply line and as return line. The hydraulic lines are also connected to a servo valve. A throttle mechanism, which features a variable flow resistance in at least one flow direction is arranged in at least one hydraulic line. The flow of hydraulic fluid through the self-regulating throttle mechanism determines the flow resistance in this flow direction, namely a higher flow resistance will occur at low flow and lower flow resistance at high flow.

Abstract: A power-assisted steering apparatus (10) for turning steerable wheels of a vehicle is provided. The apparatus (10) comprises a one-piece monolithic component (16). The one-piece monolithic component (16) includes a pinion gear portion (18) for meshingly engaging a rack bar (14), a valve sleeve portion (20) for cooperating with a valve core (100) to actuate the hydraulic motor (124), and a torsion bar portion (22) extending axially outwardly of the valve sleeve portion (20) opposite the pinion gear portion (18).

Abstract: A steering damper has a pair of damper portions each including a variable throttle valve for restricting inflow from a power cylinder into a flow passage change-over valve, the variable throttle valve provided on the way to each cylinder passage and a first check valve for permitting inflow from the flow passage change-over valve into the power cylinder, the check valve connected in parallel with the variable throttle valve. The steering damper has a second check valve in communication to a tank between the first check valve and left and right chambers of the power cylinder.

Abstract: The invention relates to a rotary slide valve (1) of servo-assisted steering systems for motor vehicles that comprises an input and an output element (3, 4), which can rotate in relation to one another around a limited angle of rotation, and comprises a coupling connection (10) of the output element (4) to a control slide (7). A torque-transmitting, non-distorted coupling connection (10) between the control slide (7) and the output element (4) is provided by a coupling pin (10), which is fixed inside the output element (4) and radially extends into a seat of the control slide (7). The seat axially tapers to a cross-section that matches the cross-section of the coupling pin (10), whereby it is easy to insert the coupling pin (10) into the seat and possible to attain a play-free supporting position for the coupling pin (10) by axially displacing the output element (4) or the coupling pin (10) and control slide (7) in relation to one another.

Abstract: To provide a power steering device capable of increasing the degree of freedom in the layout of the various elements, stabilizing the surface of the oil and preventing air from being included or mixing foreign materials with the oil in the oil tank. The power steering device includes a power assist cylinder arranged between a steering shaft and a chassis frame. A control valve is operated by the steering shaft to control the power assist cylinder. An oil pump pressurizes operating oil supplied to the power assist cylinder. Furthermore, an oil tank stores the operating oil, wherein the oil tank is of a closed type and integrally arranged in the oil pump.

Abstract: A power steering system for automotive vehicles has a construction for reducing noise generated due to pressure change of hydraulic fluid in the power steering system. In the power steering system, an orifice tube is disposed in a joint portion between the first return tube and the second return tube. The orifice tube includes an orifice tube body and a flange, the orifice tube body has an outer diameter equal to an inner diameter of the first return tube so that the orifice tube body can be inserted in the first return tube. The flange has an outer diameter equal to an inner diameter of the second return tube so that the flange can be inserted in the second return tube.

Abstract: A power steering system for a vehicle, comprises a steering shaft connected to a steering mechanism. A hydraulic power cylinder is provided for assisting a steering effort of the steering mechanism. A reversible pump is provided having first and second discharge ports which are respectively connected through first and second hydraulic lines with two hydraulic pressure chambers of the hydraulic power cylinder so that the two hydraulic pressure chambers are respectively provided with hydraulic pressures. A driving device is provided for driving the reversible pump to rightly and reversely rotate. A differential pressure regulating valve is disposed in the hydraulic circuit to maintain pressure at least in the first and second hydraulic lines at a level of atmospheric pressure or higher in an inoperative condition of the reversible pump.

Abstract: An apparatus (10) for turning steerable wheels of a vehicle comprises a housing (12). A rack bar (54) is movable longitudinally relative to the housing (12) for turning the steerable wheels. A pinion gear (68) is located within the housing (12). Teeth (76) of the pinion gear (68) are in meshing engagement with teeth of the rack bar (54). The apparatus (10) also comprises a hydraulic motor (60) for moving the rack bar (54) relative to the housing (12). A valve assembly (98), responsive to rotation of a steering wheel (94) for directing fluid to the hydraulic motor (60), has an actuated position and an unactuated position. The apparatus (10) further comprises a mechanism (156) for dampening longitudinal oscillations of the rack bar (54). The mechanism (156) comprises a yoke bearing (158) which contacts the rack bar (54) with a variable pressure that is dependent upon a velocity of rack bar (54) relative to the housing (12).

Abstract: A power steering system comprises a rotary slide valve which has a housing, an input shaft and an output shaft which can be rotated relative to each other to a limited extent. A centering piston is provided which is non-rotatably and axially movably connected with the input shaft and delimits a pressure space in the housing. The rotary slide valve further comprises a centering ring which is non-rotatably connected with the output shaft, and an inlet to the pressure chamber. The pressure chamber has a controlled outlet. There is also proposed a method of operating such a power steering system.

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 hydraulic power steering system includes a steering gear having a cylinder, and a piston slidably disposed in the cylinder to divide the cylinder into first and second cavities on opposed sides of the piston. A pair of turn tubes are coupled to the cylinder for connecting the cylinder cavities to a source of hydraulic fluid. An open fluid leakage path extends between the cylinder cavities or between the turn tubes. This open leakage path is sized to damp fluid pressure fluctuations and thereby reduce fluid-induced shudder in the steering system. The open fluid leakage path may comprise a valve or a passage extending between the turn tubes, a passage in the piston or in the seal between the piston and the gear housing cylinder, or a passage in a banjo block connected across the turn tube inputs to the gear housing.

Abstract: A positioning mechanism is provided for a moving member that moves linearly by the turning of a screw member driven by a stepping motor. A drive shaft driven to turn by the stepping motor is fitted, so that turning transmission is possible, into the screw member that screws into the moving member that is capable of moving linearly. A configuration prevents the moving member from turning together with the screw member when the screw member is turning. Origin positioning is performed, by using a stopper, by stopping the linear movement of moving member caused by driving the motor to turn in one direction. The moving member is positioned according to the turning steps of the motor in the other direction after the origin positioning. The drive shaft is fitted into the screw member via an elastic member interposed therebetween so that turning can be transmitted.

Abstract: A hydraulic power steering apparatus 1 which is arranged so that a damper valve 10 is disposed in hydraulic oil circuits 8 and 9 for connecting an oil passage selector valve 11 in a gear box with right and left oil chambers of a power cylinder 6. The damper valve 10 comprises a spool valve. And a control oil chamber 21 of the spool valve 10 is connected with a hydraulic oil feed passage 18 for connecting a hydraulic pump 13 which is driven by an internal combustion engine so as to discharge hydraulic oil, with the oil passage selector valve 11. Its back pressure chamber 17 is connected with a hydraulic oil circulating passage 19 for connecting the oil passage selector valve 11 with a reservoir tank 12. Orifices 27 and 28 are provided in connecting oil passages 22 and 20, such that when discharge oil pressure of the hydraulic pump 13 rises, opening of the spool valve 10 increase.

Abstract: A hydraulic power steering system for steering rear axles of vehicles comprises a distribution system (10) coupled to a wheel of the rear axle. The distribution system (10) has a core (12) encased in a casing (11) and rotatable to distribute pressurised fluid to a cylinder (40). The distribution system comprises resilient centring means in form of a sphere (22) and spring (23).

Abstract: A power-assisted steering apparatus (10) for turning steerable wheels of a vehicle is provided. The apparatus (10) comprises a one-piece monolithic component (16). The one-piece monolithic component (16) includes a pinion gear portion (18) for meshingly engaging a rack bar (14), a valve sleeve portion (20) for cooperating with a valve core (100) to actuate the hydraulic motor (124), and a torsion bar portion (22) extending axially outwardly of the valve sleeve portion (20) opposite the pinion gear portion (18).

Abstract: A first fluid passage extends from a first outlet/inlet port of a hydraulic pump to a first work chamber of a power cylinder, and a second fluid passage extends from a second outlet/inlet port of the pump to a second work chamber of the power cylinder. A switch system switches the role of the first and second outlet/inlet ports in accordance with a turning direction of a steering wheel. Flow control mechanisms are respectively incorporated with the first and second fluid passages, so that a controlled flow of hydraulic fluid from the hydraulic pump to the first or second work chamber and vice versa are appropriately carried out thereby providing the driver with a comfortable steering feeling. A bypass arrangement may be provided between the first and second fluid passages to deal with a residual pressure that would be remained in the first or second work chamber when the hydraulic pump is under inoperative condition.

Abstract: An auxiliary solenoid controlled variable displacement power steering pump, hydraulic systems incorporating same, and method for improving the efficiency of variable displacement power steering pumps. In one embodiment, a rotor is arranged within a pump body, and a cam fitted on an outer periphery of the rotor and movably arranged within the pump body to form a variable volume pump chamber. The cam is biased towards a position within the pump body to create maximum displacement. A mechanism is provided for forcing the cam into a position of fixed minimum or reduced displacement under certain conditions, such as low engine speed and power steering demand. In a preferred embodiment, the mechanism comprises a solenoid driven connecting rod that is operatively connected to the cam. Activation of the solenoid forces the cam to a position of fixed minimum or reduced displacement.

Abstract: A rack and pinion power steering system 10 is provided and includes a variable orifice valve 22 which controls the flow of fluid in and out of a hydraulic cylinder 20. Variable orifice valve 22 is communicatively coupled to a source of pressurized fluid 30 by use of a conduit 42 and an electronically controlled valve assembly 38. The pressurized fluid received through conduit 42 controls the operation of valve 22. Based upon the pressure of the received fluid, valve 22 selectively increases and decreases the volume of fluid flow in and out of cylinder 20, thereby causing cylinder 20 to have enhanced damping characteristics during certain vehicle operating conditions (e.g., during relatively high vehicle speed operating conditions).

Abstract: A hydrostatic steering system of the type including a fluid controller (21) for controlling the flow of fluid from a source (11) to a steering actuator (19) in response to movement of a steering wheel (W). The controller (21) is of the type having a fluid meter (65) including a moveable star member (95), the movement of which corresponds to the flow of fluid to the actuator (19). The controller includes a sensor assembly (125) which senses the movement of the star member (95) and generates an electrical signal (127) representative of the fluid flow through the fluid meter (65).

Abstract: A fluid power assist rack and pinion steering system (12) for a vehicle having steerable wheels comprises a rack (66) connected with steering linkage of the vehicle for, upon movement of the rack, moving the steering linkage to effect turning of the steerable wheels. A rotatable pinion (64) is in meshing engagement with the rack (66). The steering system (12) also includes a control valve (22) comprising a valve core (40) rotatable relative to a valve sleeve (42). A first part (56) connects the valve sleeve (42) for rotation with the pinion (64). A mechanism (38) resists relative rotation between the valve core (40) and the valve sleeve (42) as vehicle speed increases by placing axial force on the valve sleeve. A second part (170) on the valve sleeve (42) resists axial movement of the valve sleeve relative to the valve core (40).

Abstract: A brake-actuating steering and braking control system for a tracked vehicle is provided with a braking control subsystem, a steering control subsystem, and right and left side brake-actuating subsystems. The braking control subsystem includes a brake pedal and is connected to brake mechanisms of each brake-actuating subsystem. A user may depress the brake pedal to apply a braking force to right and left side track assemblies of the tracked vehicle via the brake mechanisms to thereby slow or stop the tracked vehicle. The steering control subsystem includes a steering wheel and is connected to each of the brake mechanisms. The user may rotationally displace the steering wheel, which applies a braking force to the track assembly corresponding to the direction of rotational displacement of the steering wheel via the corresponding brake mechanism to thereby turn the tracked vehicle.

Abstract: An electric powered hydraulic steering system (10) for a vehicle comprises a power steering motor (12) having a housing (18) with an exterior surface (16) and an interior chamber (24). The power steering motor (12) further includes a rack bar (26) for turning the steerable wheels of the vehicle. The rack bar (26) extends through the interior chamber (24) of the housing (18). A piston (34) is attached to the rack bar (26) and divides the interior chamber (24) into two chamber portions (38 and 40) for receiving a fluid. The piston (34) moves the rack bar (26) linearly within the interior chamber (24) depending upon a pressure differential between the two chamber portions (38 and 40).

Abstract: A steering damper has a flow passage control valve for switching and connecting among a pump, a tank and left and right chambers in a power cylinder in correspondence to a steering operation, and left and right cylinder passages (3, 4) for connecting to the left and right chambers. The steering damper is provided with left and right damper portions (10A, 10B) having variable throttle valves (6, 7) arranged in the middle of the respective cylinder passages and limiting an inflow to the flow passage control valve from the power cylinder and pilot operated check valves (8, 9) connected thereto in parallel and allowing an inflow from the flow passage control valve to the power cylinder. A pilot plunger (30) arranging them at positions close to the respective passages and sliding between the left and right damper portions is provided.

Abstract: A variable displacement pump 28 having an electronically modulated solenoid relief valve 100 for controlling fluid flow into the pump 28. An engine control module coupled to the electronic relief valve 100 monitors vehicle speed and steering wheel turning rate change directs the solenoid relief valve 100 to adjust the pressure of fluid displacing a movable cam ring 44 within the pump 28 to provide for greater fluid flow when evasive maneuvers may be required and lesser fluid flow when low steering efforts are needed, thus resulting in energy and fuel savings.

Abstract: A hydraulic steering system, which is used, in particular, for a mobile working machine, and has a steering unit that can be actuated by a first steering member, which is constructed as a steering wheel, that has a first fluid connection, which is connected to a pressure chamber of a steering motor, the pressure chamber being subjected to pressure for a steering movement to the left, and that has a second fluid connection, which is connected to a pressure chamber of the steering motor, the pressure chamber being subjected to pressure for a steering movement to the right, and which has a control valve that can be actuated by a second steering member, which is constructed in the manner of a joystick, and likewise has fluid connections that are connected to the pressure chambers of the steering motor.

Abstract: A hydraulic steering arrangement with a steering handwheel, which is connected with a hydraulic steering unit, and a steering motor, which is connected with a pump via a steering valve. In a steering arrangement of this kind an improvement of the steering comfort is desired. For this purpose, a supply line is located between the steering unit and the pump, and a pressure reduction valve is located in the supply line.

Abstract: A hydraulic power steering system (10) for turning steerable wheels of a vehicle. The system (10) comprises a steering gear (12) including a hydraulic motor and a steering valve. The steering gear is susceptible to pressure fluctuations that cause noise during steering. The system (10) further comprises a pressure relief valve (14) having an unactuated condition and actuated conditions. The pressure relief valve (14), in the unactuated condition, restricts fluid flow through the pressure relief valve (14). In an actuated condition, the pressure relief valve (14) permits fluid flow through the pressure relief valve (14). The pressure relief valve (14) progressively is operable from the unactuated condition to an actuated condition as a pressure differential between the inlet (38) and the outlet (40) of the steering gear (12) increases.

Abstract: A hydraulic power steering apparatus for a vehicle is provided with a main control valve in which a valve opening degree is controlled on the basis of a relative movement between an input shaft interlocking with a steering wheel and an output shaft interlocking with a steering mechanism for turning a steered wheel, a power cylinder mechanism generating a steering assist force, a pump apparatus discharging a fixed flow amount of working oil, a first flow passage including a supply passage communicated with the main control valve, and a control unit controlling an assist control valve. The main control valve controls a supply amount of the working oil in the first flow passage to the power steering apparatus, and the assist control valve controlling a flow amount of a part of the working oil discharged from the pump apparatus is controlled to a set valve opening degree set on the basis of a vehicle speed and an oil pressure of the working oil in the first flow passage, by the control unit.

Abstract: A power steering device includes a cylindrical holder coaxially arranged on a steering shaft, a cylindrical rotary cylinder coaxially and rotatably installed in the holder and forming two oil chambers spaced apart in a circumferential direction between it and an inner surface of the holder, and a spool changing-over member coaxially and rotatably inserted in the rotary cylinder and connected to the steering wheel. A differential mechanism is provided between the rotary cylinder and the spool changing-over member for integrally rotating the rotary cylinder and the spool changing-over member when a steering force applied to the steering shaft is low, and allowing a relative rotation between the rotary cylinder and the spool changing-over member when the steering force is larger than a predetermined value.

Abstract: The invention relates to a hydraulically assisted steering system for a motor vehicle. Because there is associated with the hydraulic system an electromechanical valve 12 which, in the open state, hydraulically indirectly or directly connects the working chambers 3 , 4, it is possible to dispense with conventional mechanical pressure limiting valves, secondary suction valves and limit stop valves.

Abstract: A hydraulic power steering apparatus 1 which is arranged so that a damper valve 10 is disposed in hydraulic oil circuits 8 and 9 for connecting an oil passage selector valve 11 in a gear box with right and left oil chambers of a power cylinder 6. The damper valve 10 comprises a spool valve. And a control oil chamber 21 of the spool valve 10 is connected with a hydraulic oil feed passage 18 for connecting a hydraulic pump 13 which is driven by an internal combustion engine so as to discharge hydraulic oil, with the oil passage selector valve 11. Its back pressure chamber 17 is connected with a hydraulic oil circulating passage 19 for connecting the oil passage selector valve 11 with a reservoir tank 12. Orifices 27 and 28 are provided in connecting oil passages 22 and 20, such that when discharge oil pressure of the hydraulic pump 13 rises, opening of the spool valve 10 increase.

Abstract: A power steering apparatus that is arranged in that hydraulic force to be supplied to a hydraulic cylinder is in a condition in which the hydraulic force is not raised even though an electric motor performs stand-by operations when a steering angle or an input torque is smaller than a predetermined value, and in that smooth steering is enabled without causing abrupt changes in hydraulic force when the steering angle or the input torgue exceedes the predetermined value and the electric motor is started driving at proper revolutions according to operations of a steering wheel.

Abstract: A hydraulic steering arrangement (1) having a steering valve (2) is described, by way of which steering valve (2) a steering motor is in communication with a pump and which steering valve (2) has a slider (3) having two end faces (8), which slider (3) can be displaced by a pressure fluid by means of a hydraulic steering unit (4) having a steering handwheel (5), the hydraulic steering unit (4) having two work connections (6) and each work connection (6) applying a work pressure to a respective end face of the two end faces (8) of the slider (3) by way of a connection (7).

Abstract: A steering valve arrangement of a hydraulic steering system has a rotary valve with a first and a second control part that are rotationally movable relative to one another. By rotational adjustment of the control parts a hydraulic servomotor is controlled which is connected drivewise with the steered wheels of a vehicle. An electric motor is mounted in a fixed location for actuating the rotary valve relative to the first control part and is connected drivewise with the second control part. The driving connection from the electric motor to the second control part is provided indirectly by a step-down transmission, including a small gear fixed to the motor drive shaft and a large gear connection with the second control part. The steering valve and the motor are disposed side by side and parallel to one another in a compact design.

Abstract: A hydraulic power steering system for motor vehicles which is suitable for a steer-by-wire operation, having a steering handle which can be operated by a driver. A servo motor operates steered vehicle wheels. A servo valve operates the servo motor and is constructed as a rotary slide valve arrangement having mutually rotationally movable control parts which, together, are pushed by a spring system into a normal position relative to one another. An actuator is coupled with the control parts for their rotational adjustment relative to one another and operates the servo valve. A desired steering angle value generator is operated by way of the manual steering handle. An actual steering angle value generator is operated by way of the steered vehicle wheels. An automatic control circuit operates the actuator as a function of a comparison of the desired and actual steering angles.

Abstract: A steering damper has a flow passage control valve for switching and connecting among a pump, a tank and left and right chambers in a power cylinder in correspondence to a steering operation, and left and right cylinder passages (3, 4) for connecting to the left and right chambers. The steering damper is provided with left and right damper portions (10A, 10B) having variable throttle valves (6, 7) arranged in the middle of the respective cylinder passages and limiting an inflow to the flow passage control valve from the power cylinder and pilot operated check valves (8, 9) connected thereto in parallel and allowing an inflow from the flow passage control valve to the power cylinder. A pilot plunger (30) arranging them at positions close to the respective passages and sliding between the left and right damper portions is provided.

Abstract: It is an object of the invention to achieve both of centering of an input shaft and an output shaft to determine relative positions of the same in a neutral state and the centering of a mechanism for applying a preset force.

Abstract: In connection with a servo-assisted steering system with hydraulic servo-assistance for motor vehicles, a steering shaft (15), which is provided with a steering wheel (16), is connected via a torsion spring (14) with an input member of a steering gear (2). An output member of the steering gear (2) is connected with the wheels (11) of the vehicle which are to be steered. In case of a relative rotation of the steering shaft (15) in respect to the input member, two work chambers (12, 13) of a servo motor of a force amplification device can be pressurized by a servo pump via a steering valve with a pressure medium. Two sensors (23, 24) for detecting a rotation angle and/or a torque are arranged on the steering shaft (15), or respectively on the output member of the steering gear (2). After the steering wheel (16) is released following a steering process, the wheels to be steered (11) and the steering gear (2) can be returned with hydraulic assistance.

Abstract: A power steering apparatus is provided which is adapted to generate a steering assist force by a hydraulic pressure generated by a pump driven by an electric motor. The apparatus includes: a steering angle detection section (11, S1, S4) for detecting an absolute steering angle on the basis of a steering angle midpoint and a relative steering angle; a first control section (31, S6, S8 to S10) for actuating the electric motor in response to the steering angle detection section detecting an absolute steering angle of not smaller than a first threshold value; and a second control section (31, S6, S11, S9, S10) for actuating the electric motor in response to a steering angle change becoming not smaller than a second thresold value which is smaller than the first threshold value when the absolute steering angle detection is not carried out by the steering angle detection section.

Abstract: A supplemental steering system is provided for a machine having first and second brakes actuable for slowing rotation of first and second drive outputs or wheels, a brake actuator, and a main or primary steering system. The brake actuator is connected with a first port and a second port of a supplemental steering control valve having a first chamber and a second chamber. The first port communicates with the first chamber and the second port communicates with the second chamber. The supplemental steering control valve further includes a piston located in the bore connected to a steering input and having a neutral position generally equidistant between the first and second chambers. First and second brake ports respectively communicate the first and second chambers with the first brake.

Abstract: A rack-pinion type power steering apparatus includes a cylindrical stub shaft, a torsion bar, a pinion shaft, a rotor, and a sleeve. The stub shaft rotates in a steering body upon a steering operation. The torsion bar has one end fixed at one end of the stub shaft and extends toward the other end of the stub shaft. The pinion shaft is pivotally connected to the other end of the torsion bar and has pinion teeth that mesh with a rack of a steering wheel. The rotor is arranged to cover the torsion bar from the stub shaft along an extending direction of the torsion bar. The sleeve has one end integrally connected to the pinion shaft, extends from the pinion shaft along the stub shaft, and is arranged around the rotor to constitute a rotary type channel selector valve between the rotor and the sleeve. At least two ends of an inner circumferential portion of the sleeve integrally connected to the pinion shaft have slidable contact surfaces that slidably support the rotor integrally connected to the stub shaft.

Abstract: A power steering apparatus, including a pump, a power cylinder, a control valve and a switching valve. The switching valve is for connecting the cylinder chambers in accordance with pressure change of the operating fluid responsive to operation of the control valve in order to return the steering wheel toward a neutral position. When the rotation of the steering wheel is substantially stopped, the switching valve reacts to the pressure change in order to connect the cylinder chambers, so as that the higher hydraulic pressure of one of the cylinder chamber releases to the other. This hydraulic pressure releasing of the operating fluid returns the power piston toward the neural position, smoothly. The steering wheel also returns toward the neutral position in accordance with the return of the cylinder piston, so as that restoring force of the steering wheel is enhanced.

Abstract: A hydraulic steering device, in particular for vehicles, is disclosed, having a housing in which two sliders are arranged to move relative to one another and together form at least one adjustable throttle, a restoring device for restoring the two sliders to their neutral position being provided, one of the two sliders being driveable and the other of the two sliders being in operative connection with a measuring device. In such a steering device it is desirable to improve the correlation between steering torque and flow amplification; in particular it is desirable to linearize the relationship better. For that purpose the measuring device is arranged in a flow path closed in itself, and operates as a pump, while an open flow path runs past the closed flow path from an inlet connection arrangement to an outlet connection arrangement.

Abstract: An electromagnetic valve for a vehicle that returns at least some of the hydraulic oil sent to a hydraulic actuator is provided. The valve has a body, two passages located at intermediate portions of two pipes, respectively, an oil path passing through the body for connecting the two passages to return the hydraulic oil from the one pipe to the other, and a valve mechanism provided within the body, the valve mechanism including a portion of the oil path and a valve body for opening and closing the oil path. Each of the two passages includes a bypass passage that does not pass through the valve mechanism. Therefore, the pressure loss of the hydraulic oil passing through the valve when the valve is closed is not significant.

Abstract: A hydraulic steering device is disclosed, having a housing in which an inner control slider and an outer control slider are arranged so that they are rotatable relative to one another and which together are arranged as alterable flow path means between a supply connection arrangement and a working connection arrangement. In such a steering device it is desirable to produce a remote control facility of simple construction. To that end, each control slider is connected to a driving slider, and between the two driving sliders there is created at least one pressure chamber which is acted upon by fluid under pressure, and a change in volume of the pressure chamber effects a relative displacement of the two control sliders.

Abstract: A hydraulic steering apparatus having a small angle of operation, can be minutely and smoothly controlled and requires a small number of operation times. The hydraulic steering apparatus is mounted onto an automatic traveling vehicle and has a pilot valve which is switched from a neutral position to a steering position upon receiving a target steering angle from a target steering angle input means. A main steering valve is switched from a neutral position to a steering position upon receiving pressurized oil from the pilot valve and outputs pressurized oil to multiple hydraulic actuators in order to produce an actual steering angle. An excitation current output means outputs an excitation current corresponding to a deviation angle between the target and actual steering angles to an electromagnetic variable pressure reducing valve.

Abstract: A system generates a brake pressure with a pump which delivers a volume into the chamber of a master brake cylinder and builds up a pressure which is used by at least one additional assembly, particularly a power-assisted steering system. The system has at least one distributing and throttling element for admitting a definable pressure to the chamber of the master brake cylinder and/or the additional assembly. The one or more distributing and throttling elements can be triggered, as a function of the brake pedal position and/or of driving condition values and/or of operating values of the vehicle, such that the chamber and/or the additional unit can be acted upon by a pump generated adjustable pressure.

Abstract: In articulated machines it has long been a desire to provide a steering system that will permit the incorporation of machine controls into a steering wheel assembly and yet provide the operator with mechanical feedback through the steering wheel. The present invention accomplishes this goal by providing a steering wheel assembly on a first frame of the machine and a control valve on the second frame that articulates with respect to the first. The steering wheel assembly and control valve are connected by a shaft assembly that includes a pair of constant velocity U-joints interposed along the length thereof. The shaft assembly translates substantially equal amounts of rotation between the steering wheel assembly and the control valve. The control valve is operable in a first and second condition, depending upon the amount of rotation of the steering wheel assembly, to provide different modes of steering that compliment the operation of the machine.