Abstract: To provide a particularly simple and cost effective design of a power-assisted steering unit for motor vehicles for supplying a servo-cylinder (3) with a hydraulic fluid as a function of the travelling speed and the steering rate, comprising a steering valve (1) by means of which the left and right chambers (16, 17) of the servo-cylinder (3) can be pressurized with hydraulic fluid via a pump (2) when there is a steering movement, and a bypass valve (10) connected in parallel to the servo-cylinder (3), by means of which a portion of the hydraulic fluid for pressurizing the servo-cylinder (3) that is directed past the servo-cylinder (3) is controlled, a throttling unit (26) is connected in series with the bypass valve (10). The hydraulic fluid inflow or return flow of the servo-cylinder (3) flows through this throttling unit (26) depending on the steering direction.

Abstract: To improve a rack and pinion steering of the generic type to reduce noise development upon opening of the pressure-relief bore as well as in steady-state operation, the invention proposes that at least one filter element forming a flow resistance be inserted between the additional bore and the pressure connection.

Abstract: A power steering system which minimizes control flow supplied to a valve mechanism when a steering assist force is not required and thereby reduces energy loss and which also prevents a deterioration in steering feeling occurring when the control flow changes. A valve mechanism V is made up of a power cylinder control valve for controlling a control flow and distributively supplying it to a power cylinder Q and a bypass control valve for bypassing the two pressure chambers of the power cylinder C; the bypass control valve is normally closed, but while the control flow Q is being increased from a minimum flow Q.sub.1 to a flow Q.sub.2 required for an assist force the bypass control valve opens and bypasses the two pressure chambers of the power cylinder C so that the pressure difference between the pressure chambers rises more gently than the control flow and the driver does not experience a feeling of the steering wheel suddenly being taken over.

Abstract: A power steering system, in particular for motor vehicles, includes a steering valve (15), for controlling a pressure medium for a servomotor, has two inlet seat valves (23, 24) and two outlet seat valves (25, 26), each with one closing body (31; 36). The closing bodies (36) of the outlet seat valves (25, 26) are actuatable via an actuating device as a function of a rotary motion of a steering-wheel shaft connected to an input member (10) of the steering system. The closing bodies (31) of the inlet seat valves (23, 24) are hydraulically pressure balanced with reference to a pressure of a pressure source, and by the force of locking springs (32) they keep the inlet seat valves (23, 24) closed in the neutral position of the steering valve. Each locking spring (32) is supported at one end on a closing body (31) of one of the inlet seat valves (23, 24) and on the other on the actuating device. The outlet seat valves (25, 26) are opened in the neutral position of the steering valve (15).

Abstract: A vehicle power steering system comprising a power unit, a valve unit and a centering unit. A piston of the power unit reciprocates in a cylinder to provide power assisted steering and is engaged by a worm connected to the steering shaft for rotation in response to either the centering unit or the vehicle steering member. The valve unit is connected between the worm of the power unit and a steering shaft segment from the centering unit, and includes a rotary valve member rigidly fixed to the steering shaft segment and rotatably received in the bore of a sleeve member fixed to the worm. The sleeve member is connected to the rotary valve member through a torsion rod arranged to actuate a pair of spool valves formed by valving elements on the rotary valve member and the sleeve member.

Abstract: A power steering system includes a fluid pump, a steering gear, a high-pressure passage connecting the fluid pump to the steering gear, and a flow control valve having a first chamber forming a part of the high-pressure passage. A metering orifice is disposed in the high-pressure passage between the first chamber and the steering gear. A feedback passage distributes feedback pressure developed in the high-pressure passage downstream of the metering orifice to a second chamber of the flow control valve. An exhaust port communicates with the first chamber. A movable valve spool is disposed in a valve bore and has one end exposed to the first chamber and opposite end exposed to the second chamber. A valve spring is disposed in the second chamber together with a slide coupled with an external actuator. One end of the valve spring is seated on the opposite end of the valve spool and opposite end thereof is seated on the slide.

Abstract: A power assisted, vacuum actuated steering system with a rotary valve and vacuum actuators. The rotary valve has two identical discs which each include grooves and channels for communicating the vacuum pressure to the vacuum actuators. The relative rotary motion of the two discs causes the vacuum pressure to pass to the vacuum actuators to assist the steering of a vehicle. A set of springs and spring arms biases the discs to a central, neutral position.

Abstract: A steering power assist apparatus is comprised of a power cylinder whose operation is controlled by the a flow rate control valve, a first control valve and a second control valve. The flow rate control valve is connected to a discharge side of a hydraulic pump and controls the amount of the hydraulic oil to be supplied to the first and second control valves according to a load pressure. The first control valve constituted by choke valves is disposed downstream of the flow rate control valve and controls the amount of the hydraulic oil supplied to the second control valve according to a steering torque. The second control valve constituted by choke valves is disposed downstream of the flow rate control valve and controls the amount of the hydraulic oil to the power cylinder according to a steering torque. The choke valves of the second control valve are fully closed after the choke valves of the first control valve are fully closed.

Abstract: An adjustable power steering valve for a vehicle steering system for selectively varying the pump pressure to the steering box. The power steering valve is positioned between the pressure line from the pump to the steering box and the return line from the steering box to the reservoir. It functions, when closed, to apply fall pump pressure to the steering box. The power steering valve can be opened to a predetermined adjustable position to bypass fluid from the pressure line to the return line to selectively reduce the fluid pressure applied to the steering box.

Abstract: A power assisted steering apparatus for a vehicle has a driving source and an actuator for the vehicle's steering mechanism, to power assist the steering operation. The driving source, such as an engine, continuously drives a pump. A working passage is arranged so that working oil discharged from the pump is introduced into the actuator. A check valve is disposed in the working passage, between the actuator and the pump so that the working oil flows only one way to the actuator. An accumulator is connected to the working passage, between the check valve and the actuator to maintain a predetermined pressure in the working passage. A regulator is connected to the working passage, between the pump and the check valve to regulate flow to the actuator. When the pressure within the working passage reaches the predetermined pressure, the working fluid is dumped to a reservoir, bypassing the check valve, the accumulator, and the actuator.

Abstract: An object of the present invention is to provide a power steering apparatus in which its neutral rigidity can be raised by applying a preset force and which is superior in its assembly performance and productivity.To attain this object, first supporting portions are formed in a pair of spring members disposed across the input shaft, and second supporting portions are formed in the input shaft so as to oppose the first supporting portions. When the input shaft and the output shaft are rotated relative to each other so that the balls or rollers are about to slip out of the first and second supporting portions, the balls or rollers roll and move while deflecting the spring members.

Abstract: In a servo-assisted steering system which is intended for motor vehicles, a steering valve (1) is provided for controlling the pressure fluid. The steering valve (1) has two intake seat valves (7, 8) and two outlet seat valves (10, 11), which are adjustable via an actuating device (23) as a function of a rotary motion of a steering shaft. In the neutral position of the steering valve (1), the outlet seat valves (10, 11) are closed. The intake seat valves (7, 8) can be acted upon in the closing direction by the force of compression springs (13) and are not opened until after the closure of the respective associated outlet seat valve (10, 11). One limiting piston (24) is provided for each side of the steering valve (1).

Abstract: A hydraulic power steering system for a vehicle comprising a hydraulic fluid displacement pump, operated by a thermal engine of the vehicle and provided with a suction port and a delivery port, a reservoir for collecting said fluid, connected to suction port, a double-acting hydraulic cylinder, capable of controlling direction of front wheels of the vehicle, and a distribution unit fitted with an inlet port, connected to delivery port, a vent port, connected to reservoir and two service ports, connected to respective chambers of hydraulic cylinder; distribution unit comprising a first and a second distributor, respectively controlled by hydraulic cylinder and by a steering wheel of the vehicle and movable with respect to each other; pump being of the variable displacement type and system further comprising a flow request sensor from and to chambers of cylinder and a device for adjusting displacement of pump, controlled by sensor.

Abstract: A vehicle steering apparatus (10) includes a fluid motor (42) having first and second chambers (44, 46). A relatively rotatable, coaxial valve core (22) and valve sleeve (24) control the fluid pressure in the chambers (44, 46). The valve sleeve (24) has first and second recesses (72a, 74a) spaced around an axis (26) on opposite sides of a fluid inlet port (70a). The valve core (22) has a third recess (80a) which communicates the port (70a) with the first and second recesses (72a, 74a) when the valve core and valve sleeve (24) are in the neutral position. The valve core (22) has first and second axially extending lands (90a, 90b) on opposite sides of the third recess (80a) and land surfaces (92a, 92b) facing the first and second recesses (72a, 74a). The valve core (22) has a first passage (100a) for communicating with the first recess (72a) and a second passage (100b) for communicating with the second recess (74a) when in the neutral position.

Abstract: A motor vehicle power steering gear has a proportional control valve with a cylindrical valve member riding rotatably on a spool shaft and connected thereto through a torsion bar. Electromagnetic apparatus for varying the magnitude of the effective restoring torque of the torsion bar comprises a stationary exciting coil, an inner pole member comprising an extension of the cylindrical valve member having a plurality of outwardly facing teeth and an outer pole member fixed on the spool shaft for rotation therewith and having an equal plurality of opposing inwardly facing teeth, the teeth defining an air gap axially beside the coil.

Abstract: A variable assist power steering system (10) uses both vehicle speed and steering valve inlet pressure to vary the steering assist provided. A system controller (30) receives speed and pressure data from sensors (24, 26) and produces a control signal for an actuator (28) that shunts fluid flow from the pump (22) to the steering valve (20) thereby affecting steering valve pressure which controls the rack piston (16) which changes the angle of the front vehicle wheels used for steering. The controller (30) employs a calibration table (32) with entries representing actuator current, vehicle speed and inlet pressure wherein the speed and pressure fall into ranges defined by equally spaced speed points and equally or unequally spaced pressure points. Having pressure points spaced with a distance between any two sequential points a power of two in sensor counts allows manageable bilinear interpolation of current versus speed and pressure without complicated divide operators.

Abstract: A portion of an oil path between an actuator for generating steering assistance power and a pump is formed by the inside space S in a housing covering an input shaft. A bearing assembly supporting the input shaft in the inside space has a bearing joined to one of the outer and inner circumferences of a circular spacer, and is inserted between the outer circumference of the input shaft and the inner circumference of the housing via radial clearances. The displacement of the bearing assembly toward one axial direction can be restrained by the contact between the contact portion formed on the other of the circumferences of the spacer and the receiving portion formed on either the housing or the input shaft, and the bearing assembly is pressed toward one axial direction by the oil pressure in the inside space.

Abstract: A hydraulic control system for work vehicles including a control unit to control the steering wheels of a vehicle via a cylinder and a priority valve which by a first load-sensing system controls the pressure fluid flow to the control unit and to a subsequent proportional valve group. By a second load-sensing system the proportional valve group controls the pressure fluid flow to secondary hydraulic motors or work cylinders to control the work tools of the vehicle. The control system also includes an open-centre valve connection and a fixed displacement pump. The first load-sensing system is connected with a second load-sensing system, whereby drop-off of the pressure fluid flow to the control unit is avoided at simultaneous operation of the latter and of one or several of the proportional valves as is the case with known control systems. Hereby a control system is provided which is particularly agreeable to operate for the driver of the work vehicle.

Abstract: A torsion element (1) for a steering valve is provided. The torsion element (1) comprises a torsionally elastic rod member (2) having axially opposite first and second end areas (3, 4) which are rotatable relative to one another. The rod member (2) has a circumferentially spaced plurality of radially and axially extending indentations (10) adjacent the second end area. A generally tubular, torsionally stiff sleeve member (6) encircles the rod member (2) and is fixedly attached to the first end area (4) of the rod member. The sleeve member (6) includes a circumferentially spaced plurality of radially and axially extending grooves (9) which align with and radially overlie the plurality of indentations (10) in a neutral steering condition. The sleeve member (6) further includes a circumferentially spaced plurality of radial slots (7).

Abstract: The invention changes over to another steering ratio automatically and very safely on the transition from servo to emergency operation. In the steering system, only a few of the lines (13) link the metering pump (10) to one of the cylinder connections (7, 8) and in each of the other lines (13') there is a changeover unit (16) which also links the lines (13) to the cylinder connections (7, 8) or the delivery connection (6) depending on the method of operation. These steering systems are used in mobile systems, especially slow-moving vehicles.

Abstract: In a power steering apparatus comprising a pump, a reservior, a power cylinder having two opposite chambers, and a rotary control vale, the rotary control valve consists of a first control portion which communicates between the pump and the reservior, and a second control portion which communicates not only between the pump and the reservior but also with the power cylinder. In the first control portion, each of four underlapping variable orifices is so provided as to take the form of underlap in itself. In the second control portion, two underlapping variable orifices are provided on the side of the pump, and besides each of two overlapping variable orifices is so provided as to take the form of overlap in itself on the side of the reservior. In this manner, while a steering wheel is operated within a predetermined angle, an opening area of the overlapping variable orifice changes little.

Abstract: A power steering gear for a motor vehicle including a pinion head and a spool shaft rotatable relative to each other, a torsion bar between the spool shaft and the pinion head, a valve spool formed integrally on the spool shaft, a valve body closely received on the spool shaft around the valve spool and rotatable relative to the spool shaft, and a tripod joint coupling the valve body to the pinion head for unitary rotation and consisting of three equally angularly spaced slots in an end of the valve body and three equally angularly spaced radial pins on the pinion head each having a spherical lobe closely received in a corresponding one of the slots in the valve body. An inboard end of the spool shaft adjacent the pinion head is unsupported laterally on the pinion head except through the valve body and the tripod joint and, consequently, floats with the valve body in the event of lateral runout between the pinion head and the spool shaft to minimize valve hysteresis attributable to such lateral runout.

Abstract: A power steering control valve (10) includes inner and outer valve members (30 and 32) which are rotatable relative to each other to control fluid flow to and from a power steering motor. A damping assembly (60) is provided to damp relative movement between the inner and outer valve members (30 and 32). The damping assembly (60) includes a pair of pistons (64 and 66) which are connected with the inner valve member (30) and extend into arcuate grooves (70 and 72) in the outer valve member (32). The pistons (64 and 66) cooperate with the arcuate grooves (70 and 72) in the outer valve member (32) to form variable volume chambers (76, 78, 80 and 82). Upon relative rotation between the inner and outer valve members (30 and 32) in a first (clockwise) direction, the pistons (64 and 66) are moved relative to the outer valve member (32) to contract a pair of chambers (76 and 82) and force fluid from the contracting chambers through restrictors (84 and 90) to a return fluid flow from the power steering motor.

Abstract: A control valve is provided for use in a hydraulic steering system of an agricultural vehicle of the type having a steering valve of the reactive type for controlling the supply of hydraulic fluid to hydraulic cylinders having opposed working chambers serving to move the steerable vehicle wheels in opposite directions. The control valve is connectable between the steering valve and the hydraulic cylinders and has a first setting in which fluid flow in both directions between the steering valve and the working chambers of the hydraulic steering cylinders is possible at all times and a second setting in which return flow of hydraulic fluid from any one working chamber of the hydraulic cylinders to the steering valve is only possible when a positive pressure is present at the outlet of the steering valve connected by the control valve to the opposed working chamber of the hydraulic cylinders.

Abstract: A power steering system for on-the-road and off-the-road vehicles includes a positive displacement hydraulic power steering pump, a master power gear with a rotary valve and a slave power gear mounted in tandem with the master power gear. Heated return hydraulic fluid from the master power gear flows through a heat transfer passage in the slave power gear and is cooled.

Abstract: In order to additionally develop a conventional steering valve in such a way that it has a simple and economical design and is insensitive to pressure pulsations, a conventional steering valve is additionally developed by arranging at least one essentially coaxial chamber that extends in the shape of an arc and can be charged with hydraulic pressure either directly or indirectly on the input shaft or the output shaft, with at least one piston element that is directly or indirectly connected to the other shaft being arranged in the aforementioned chamber such that it can be moved along an essentially arc-shaped path.

Abstract: A vehicle speed responsive power steering apparatus enables a pressure which acts upon a power cylinder to be variably controlled in accordance with a vehicle speed or the like, thus allowing an assisting force to be controlled in a variable manner. A control valve CV selectively connects a pump P and a tank T to left and right chambers CL, CR of a power cylinder. The control valve comprises a first and a second fluid pressure bridge circuit 10, 20. The first fluid pressure bridge circuit includes a left and a right path 12, 13, in which a first and a second pair of variable throttles 1R, 1L and 2L, 2R are disposed which are opened or closed in response to a steering operation. The left and the right chamber of the cylinder are connected to the respective paths at the junctions between the variable throttles.

Abstract: A motor vehicle power steering gear has a proportional control valve with a cylindrical valve member riding rotatably on a spool shaft and connected thereto through a torsion rod. Electromagnetic apparatus for varying the magnitude of the effective restoring torque of the torsion rod comprises a stationary exciting coil, an extension of the cylindrical valve member having a plurality of outwardly facing teeth and an outer pole member fixed on the spool shaft for rotation therewith and having an equal plurality of opposing inwardly facing teeth, the teeth defining an air gap axially beside the coil. The cylindrical valve member is formed with a pair of sleeve surfaces for riding on the spool shaft surface with a small controlled clearance providing a hydraulic seal; and faces of the teeth of the cylindrical valve member and outer pole member are both machined after formation of the members for accurate control of the radial distance thereof from the spool shaft surface and thus of the air gap.

Abstract: A power steering system includes first and second valve members (40 and 42) which are movable relative to each other to port fluid to a vehicle power steering motor (31) and a pump (24) for providing fluid to the first and second valve members (40 and 42) and the power steering motor. A force transmitting member (116) is connected with the first valve member (40) and movable toward and away from the second valve member (42) for applying a force to resist relative movement between the first and second valve members. A fluid pressure chamber (138) receives fluid from the pump (24), the pressure of which acts on the force transmitting member (116). The first and second valve members (40 and 42) include passages for conducting fluid to the fluid pressure chamber (138). A fixed size bleed orifice (182) conducts fluid from the pressure chamber (138) to a reservoir (32). The orifice (182) restricts the flow of fluid from the chamber (138) to the reservoir (32).

Abstract: A rotary slide valve for power-assisted steering mechanisms of motor vehicles has two valve elements (1, 2) which are arranged to be coaxially movable within each other and are connected with each other via a torsion rod (7) and a backlash coupling (8) in such a way that they are rotatable around each other by maximally the pivot path of the backlash coupling. The inner valve element (1) is connected with a valve inlet member (3) and the outer valve element (2) with a valve outlet member (4), fixed against relative rotation. The one part of the backlash coupling (8) is formed on the radially inner valve element (1) by claws (10) which project in relation to its front face in the axial direction. The other part of the backlash coupling (8) is constituted by two pins (11) which are disposed parallel with each other in the radially outer valve element (2), whose axes (12) are located in a plane (13) extending perpendicularly in respect to the axis (14) of the rotary slide valve.

Abstract: A power steering gear including a spool shaft, a pinion head, a torsion bar between the spool shaft and the pinion head, and a rotary detent which resists twisting of the torsion bar including an annular first ball seat rotatable as a unit with a pinion head end of the torsion bar, an annular second ball seat facing the first ball seat, a plurality of detent notches in the first and second ball seats facing each other in pairs, a plurality of detent balls between the facing pairs of detent notches, a plain cylindrical sleeve around the torsion bar rigidly connected at a first end thereof to the second ball seat, a pair of radial abutments on the torsion bar near a spool shaft end thereof, and a pair of cantilever springs at a second end of the cylindrical sleeve having lateral deflection strokes perpendicular to a longitudinal centerline of the torsion bar and ramps which resiliently capture therebetween the radial abutments.

Abstract: In a device for controlling the pressure to be supplied to a hydrostatic steering unit (1) by means of a control signal (s), there is a rotary slide valve arrangement, one slide valve element of which is rotatable by means of a steering means (5) and the other side valve element of which is corrected by means of a measuring motor (16). Together with a series throttle (AV), a control throttle (AS) forms a series circuit independent of the intake path of the steering motor (4), which circuit is connected between a pressure source (CF) and the tank (6). The control throttle (AS) has a closing characteristic that extends substantially across the entire working range of the angle of rotation of the slide valve elements. The control signal (s) is tapped between the series throttle (AV) and the control throttle (AS). This provides a pressure control that is independent of load.

Abstract: A power assistance steering system for use in a vehicle comprises a restricting mechanism including a cylindrical reaction piston having a reaction surface on which said reaction pressure is applied in order to cause said reaction piston to be biased downwardly, and at least one reversed V-shaped depression formed on a bottom skirt, the cylindrical reaction piston adapted to be held on the input shaft in such a way that said reaction piston can longitudinally and slidably reciprocate with respect to the input shaft, while circumferentially locked to the input shaft, and at least one semi-spherical protrusion formed on a middle end surface of said output shaft so as to be retained within the reversed V-shaped depression.

Abstract: The invention relates to a servo-assisted rack-and-pinion steering system having a helical-toothed rack and an axially movable pinion which interacts therewith and the axial movement of which controls the servomotor. The pinion is mounted on an input shaft in such a manner as to be incapable of rotation with respect to the shaft but axially movable thereon, in order to suppress the transmission of axial forces between the input shaft and the pinion.

Abstract: The invention relates to the control of a servo valve, in particular in a power steering system of a motor vehicle. Of two valve control parts which are coupled to one another with torsional elasticity by a torsion bar, one is connected merely non-positively to the assigned end of the torsion bar or to a part, which is arranged securely against rotation at the said end, in order to allow an adjustment while overcoming the non-positive engagement.

Abstract: In a servo-steering unit provided for motor vehicles, one pinion (2) supported in a steering housing (1) meshes with a rack (6). A steering valve (8) which serves to control the pressurized fluid for the servo-steering unit has two inlet seat valves (10, 11) and two outlet seat valves (12, 13) the closing members of which are movable via actuating tappets depending upon rotation of a steering spindle. The outlet seat valves (12, 13) are open in the neutral position of the steering valve. The inlet seat valves (10, 11) are actuatable in a closing direction by the force of pressure springs and are opened only after closing of the respective outlet seat valve (12, 13). A limiting piston (31) is provided for each side of the steering valve (8). Each limiting piston (31) is actuated on one side by one of the centering springs (30) and by a first pressure prevailing in a working chamber of a servo-motor and on the other side by a limiting force.

Abstract: A power steering apparatus is composed a fluid source for discharging pressurized fluid, a power cylinder, a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid from the fluid source, and a reservoir. The control valve has a first control portion for controlling the flow of pressurized fluid from the fluid source to the reservoir, and a second control portion for controlling the flow of pressurized fluid to the power cylinder. The first control portion has four paths communicating with the fluid source and the reservoir, and each of the four paths is formed with a center-open variable orifice which opens when the control valve is in a neutral state.

Abstract: A main servo valve 4 is switched in response to a relative angular displacement between an input and an output shaft for supplying an operating oil discharged from a pump to or displacing such operating oil from a power cylinder 6. An auxiliary servo valve 10 is disposed between the input and the output shaft and is connected in parallel relationship with the main servo valve 4 so as to be operated jointly therewith. A vehicle speed responsive valve 16 which opens or closes a flow path in accordance with the vehicle speed is disposed upstream of the auxiliary servo valve 10. The pump comprises a pair of pumps 2, 12 of smaller size. At low speeds, the speed responsive valve 16 is closed, and the oil discharged from the pair of pumps 2, 12 are merged to be introduced into the main servo valve 4. As the vehicle speed increases, the speed responsive valve 16 is gradually opened, and at a vehicle speed above a given value, one of the pumps, 12, ceases to operate.

Abstract: Unbalanced oscillatory pressures, developed on the power piston of hydraulic servoactuator systems cause vibrations on actuator housing supports. An unbalanced oscillatory force results, when two sides of the power piston are subjected to two unequal oscillatory forces induced by a disturbance. The two important disturbances are: pump flow rate oscillations, caused by power source torque oscillations; and, load oscillations. The invention is a hydraulic actuator connected in parallel to the power piston and designed to cancel vibrations by eliminating the unbalanced oscillatory pressure on the power piston. This is accomplished by designing the piston frequency of the invention, defined as tuning frequency, to be equal to the unbalanced oscillatory pressure frequency.

Abstract: A power assisted steering system, in particular, for motor vehicles, contains a servomotor (2), a servopump (3), a tank (4), a control valve (1) with a controllable feedback device (5), and a control member (46) whose choke cross section can be altered as a function of the vehicle speed. Control valve (1) is made as a four-way valve and has a supply connection (22, 23), a feedback connection (7), and two working connections (8, 10) for the lines (11, 12) that lead to the two working chambers of servomotor (2). Between feedback device (5) and supply connection (22, 23), there is arranged a device (13) for piling up the pressure medium stream and the device is made according to one practical example as a choke (50, 51). With the help of this choke (50, 51), one can achieve a hydraulic centering component in addition to a mechanical centering component.

Abstract: A variable assist power steering system for a motor vehicle has an electronically controlled working pressure valve which normally maintains a working pressure at a relief pressure but increases it in response to steering of the vehicle and according to vehicle status, such as vehicle speed. The system also has electronically controlled direction control valves which are actuated to selectively reduce the working pressure to one side or the other of the steering gear piston so as to match a measured handwheel torque with a value which is desired for the vehicle status.

Abstract: A rotary slide valve (1) for power-assisted steering systems of motor vehicles contains a rotary slide (2) that is guided in a limited rotary fashion in a control box (3). Control box (3) is connected with a valve exit member (7) in a nonrotating manner. Rotary slide (2) is connected with valve exit member (7) via a torsion rod (9) and a dead-travel clutch (10). Dead-travel clutch (10) consists of a catch section piece (16) of the valve exit member (7) and of recesses (17) that are fashioned on the free end of rotary slide (2). Rotary slide (2) with its longitudinal control grooves (12, 13) and with its recesses (17) is made by way of a noncutting production process. This production process is simplified and the rotary slide valve (1) is made smaller in that the recesses (17) of rotary slide (2) are arranged in longitudinal control grooves (13) of rotary slide (2) that are open toward one end.

Abstract: A hydraulic power rack and pinion steering assembly (10) includes a valve core (98) and a valve sleeve (100) which are supported for relative rotation. A damping ring assembly (150) is interposed between the valve parts (98, 100) to reduce vibrations and thereby to attenuate noise. The damping ring assembly (150) includes an inner ring (160) press fit on the valve core (98) and an outer ring (170) press fit in the valve sleeve (100). An elastomeric member (180) is disposed in the annulus between the inner ring (160) and the outer ring (170). The elastomeric member (180) is bonded to the inner ring (160). Ribs (210-216) on the inner ring (170) are received in grooves (270-276) in the elastomeric member (180). The ribs (210-216) sequentially engage the elastomeric member (180) upon incremental relative rotation between the valve parts (98, 100) to provide a damping effect which changes at an increasing rate as the valve parts move from the centered condition.

Abstract: A power steering apparatus comprises a fluid source for supplying pressurized fluid, a power cylinder having a pair of fluid chambers, a control valve, and a drain control mechanism. The control valve is composed of first and second control portions. The first control portion has four paths connecting the fluid source and the reservoir, and each of the four paths is formed with a variable orifice of center-open type. The second control portion has two supply paths communicating the fluid source with the fluid chambers of the power cylinder, each of the supply paths being formed with a variable orifice of center-open type, and two drain paths communicating the fluid chambers with the reservoir, each of the drain paths being formed with a variable orifice of center-closed type.

Abstract: A rotary slide valve (1) for auxiliary power steering systems in motor vehicles contains in a valve borehole (5) of a valve housing (2) a rotary slide (4) that is connected with a steering spindle connection (23). In an axial borehole (6) of the rotary slide (4), a control sleeve (7) is guided so that it can be turned by a limited angle. Rotary slide (4) in its axial borehole (6) has longitudinal control grooves (20) that cooperate with longitudinal control grooves (21) on the outer generated surface of control sleeve (7). The inside-located control sleeve (7) is made by means of a non-cutting production process and can thus have relatively small dimensions. With the help of such a process, for example, by means of cold shaping, one can make both the longitudinal control grooves (21) and the control edges of control sleeve (7). The entire rotary slide valve (1) can be made in a very compact fashion as a result of the small dimensions of control sleeve (7).

Abstract: An auxiliary power steering unit, especially for motor vehicles, contains a control valve (1) made as a rotary slide valve for controlling a pressure medium conveyed by a servopump (3) out of a tank (4) to and from the pressure chambers of a servomotor (2). Control valve (1) reveals two feedback chambers (10, 11) that are connected via one, each, fixed throttle (12, 13) and a common throttle (14) to a pressure line (15) of the servopump (3). The feedback pressure that takes effect in the feedback chambers (10, 11) can be limited to a maximum value by a cutoff valve (18). The cutoff valve (18) is made as pressure balance whose response pressure can be adjusted from the outside without dismantling.

Abstract: In a servo steering unit which is designed particularly for motor vehicles, a pinion in a steering housing meshes with a steering rack. A steering valve which serves to control the pressure medium for the servo steering unit has two inlet seat valves (10, 11) and two outlet seat valves (12, 13) whose closing members (14, 18) are displaced by actuating tappets (16, 17) depending on the rotation of a steering spindle. The outlet seat valves (12, 13) are open in the neutral position of the steering valve. The inlet seat valves (10, 11) can be actuated by the force of pressure springs (15) in the closing direction and are not opened until after closing of the associated outlet seat valve (12, 13). The pressure springs of both inlet seat valves (10, 11) on one side press against the actuating tappets (16, 17) and on the other side press constantly on the closing member (14).