Abstract: The invention relates to a rotary slide valve subassembly for a hydrostatic steering unit. The slide valve subassembly includes two concentric sleeves having near one end a plurality of circumferentially distributed axially extending slots which, in the neutral position, create a short circuit between the supply and discharge sides. The slots subdivide the corresponding sleeve sections into stays extending from the main sleeve sections. A construction is provided to avoid jamming of the sleeves by joining the stays of each sleeve section with a closed ring member and undercutting the inside diameter of the stays of the inner sleeve section to cause weakening thereof relative to the stays of the outer sleeve section.

Abstract: A power steering device having a fluid pressure cylinder of a single rod type providing like output characteristics for steering both rightwardly and leftwardly. A rod-side chamber and a head-side chamber of the fluid pressure cylinder have different pressure receiving areas. A control valve controls the changeover of a flow path among a pump, a tank and the rod-side and head-side chambers in accordance with the movement of a steering wheel such that the rod-side chamber is connected to the pump and the tank is connected to the head-side chamber when the piston is to be moved toward the head-side chamber, and the pump is connected to both the head-side chamber and the rod-side chamber when the piston is to be moved toward the rod-side chamber.

Abstract: A power steering gear mechanism for an automotive vehicle having a pressure operated vehicle steering mechanism controlled by a rotary valve with primary and secondary valve portions located in angularly spaced relationship on a common transverse reference plane wherein the primary valve portion develops a fast-rising steering pressure characteristic for incremental changes in steering torque at low driving speeds and a flatter or more gradual steering pressure rise characteristic for incremental changes in steering torque at high driving speeds, the latter resulting from the action of the secondary valve portion which functions in cooperation with the primary valve portion whereby the pressure versus torque relationship is optimized for parking maneuvers, for driving maneuvers and for center-feel, the change from the low speed steering mode to the high speed steering mode being gradual whereby the center-feel increases in proportion to increasing road speed.

Abstract: A rack and pinion steering gear mechanism for a wheeled vehicle comprising an input shaft, a rotary fluid pressure control valve and a drive pinion for a rack wherein the pinion is located between the input shaft and the valve and wherein the pinion has a central opening for receiving therethrough a valve actuator rod and a torsion bar that connects the input shaft to the pinion.

Abstract: A closed-center, non load-sensing controller (15) is disclosed for use with an unequal area steering cylinder (17). The controller includes valving comprising a spool (35) and sleeve (37). The sleeve includes an annular groove (65) in communication with the inlet port (29) and cylinder ports (73,75) in communication with the opposite ends of the steering cylinder. The sleeve defines an annular leakage groove (95) which is disposed to interrupt the flow of leakage fluid from the annular groove (65) to the cylinder ports (73,75), to eliminate undesired piston rod extension. When the valving is in neutral, leakage fluid collected in the annular groove (95) is communicated through radial bore (97), axial slots (83), and annular groove (81), axial slots (91), drain bore (99), drain bore (93), and then to the system reservoir.

Abstract: The star-shaped rotor (10) accommodated in a discoid cavity (9) defines first chambers (27) formed in the arms (20) of the rotor and second chambers (26) for receiving fluid under pressure delimited between two adjacent arms of the rotor, the constitutive elements of the stator (3-5) being joined together by fastening means (50) extending through the second chambers (26), the lateral faces of the cavity opposite the stator incorporating passage apertures (32', 33) which have a trapezoidal profile with radial edges coincide substantially with the web zones (31) of the arms of the rotor, the edges of which define with the edges of the apertures adjustable restrictions (250, 280) the first chambers (27) communicating permanently with return passages (38) in the stator.

Abstract: A power steering gear for controlling the dirigible wheels of an automotive vehicle comprising steering gear elements and a fluid motor adapted to drive the steering gear elements to supplement the manual steering effort comprising a rotary valve assembly for controlling distribution of steering pressure from a pressure source to the fluid motor including a sleeve element and a spool element, each valve element having cooperating lands for controlling distribution of pressurized fluid therethrough to effect a pressure buildup in a pressure supply port that communicates with a working chamber of the fluid motor and chamfered surfaces on the valve lands of the internal valve element whereby pressure drop in the pressurized fluid circulated through the valve system and fluid noise is reduced and response of the valve system to steering maneuvers is improved.

Abstract: The invention relates to a pneumatically driven control valve for the reversible operation of a pneumatic unit. In an addition to an air distribution system for regulating the speed of the pneumatic unit, the control valve incorporates an air volume control system which is fully integrated into the air distribution system. The key component is a rotary slide valve, the rotation of which distributes the compressed air while its axial displacement throttles the air stream flowing through the valve, the degree of throttling depending upon the pressure level of the compressed air delivered to the pneumatic unit. In this way, the control valve is kept simple in construction with very few moving parts and high functional accuracy.

Abstract: A rotor (23) is mounted for rotation in a housing (10) having a pressure chamber (31) and an exhaust chamber (33) formed about the rotor. The rotor is provided with slots (36 and 37) which are moved sequentially in pairs into alignment with plungers (48 and 68). When a plunger (48) partially overlays a slot (36), pressurized air passes from chamber (32), through an exposed portion of a slot (36), through plungers openings (49, 44, and 43) to one end of an air cylinder (12) while exhaust atmospheric pressure is presented from chamber (33), through an exposed portion of a slot (37), through a plunger openings (71, 67, 64, and 63) to the opposite end of the air cylinder (12) to permit movement of a piston (83) to drive some external mechanism.

Abstract: Power-assisted rack-and-pinion steering mechanism with a slide-valve which senses the axial thrusts acting on the pinion through a kinematic mechanism with a high transmission ratio, the slide member of the valve consisting of a piston 9 provided with frontal rims 11 and 12 on each end face, cooperating with associated seats formed on the housing, said rims and seats forming varying passages through which the two actuator chambers are connected to the reservoir, means being provided for varying also the communication between the same chambers and the pump, depending on the torque applied to the pinion, piston, seats and housing being so designed that the fluid pressure existing in the operative chamber acts on one or the other piston end face and thus gives the driver the measure of the same pressure.The system is particularly suitable for a vacuum operated power-steering system which permits a very strong reduction in cost in comparison with a conventional hydraulic power-steering system.

Abstract: The invention relates to a hydrostatic steering control unit of the type having valving for an open center neutral position which bypasses pressurized fluid from the pump to the tank when in neutral. During a turning operation with a steering wheel the open center valving is caused to close and the pressurized fluid is directed to one side or the other of a servomotor which is connected to wheels to be steered. The open center valving includes orifices in relatively rotatable elements which are aligned in the neutral position and closed to effect the turning operation. Open center valving can be the cause of noise and cavitation and such valving herein is provided with slot shaped orifices and flat generally wedge shaped throttle passages to minimize the noise and cavitation problems. The throttle passages are defined by curved bounding surfaces having rectangularly shaped outlines.

Abstract: The invention relates to a hydrostatic steering control unit of the type having valving for an open center neutral position which bypasses pressurized fluid from the pump to the tank when in neutral. During a turning operation with a steering wheel the open center valving is caused to close and the pressurized fluid is directed to one side or the other of a servomotor which is connected to wheels to be steered. The open center valving includes orifices in relatively rotatable elements which are aligned in the neutral position and closed to effect the turning operation. Open center valving can be the cause of noise and cavitation and such valving herein is provided with slot shaped orifices and flat generally wedge shaped throttle passages to minimize the noise and cavitation problems. The throttle passages are defined by curved bounding surfaces having rectangularly shaped outlines. A characteristic of the curved surfaces is that they are formed with exponentially shaped sections.

Abstract: A hydraulic distributor device comprises two members movable relative to one another, either in rotary or translational movement, along a planar sliding interface, at least one narrow groove being provided superficially in one of the members along the interface, so as to minimize or eliminate the axial thrust generated by the fluid pressure. The distributor device may be used in power-assisted steering apparatus for a vehicle.

Abstract: An auxiliary fluid power steering device having a servomotor (8) and a control valve (13) in a common steering gear housing (1). In order to relieve the control valve of axial pressure forces, the valve body (14) of the control valve has four surfaces (24, 25, 26, 27) of equal area respectively exposed exclusively to fluid in the inlet port (22), in the outlet port (23), in one of the servomotor pressure chambers (9) adjacent the control valve and in the other pressure chamber (10) of the servomotor.

Abstract: A power-assisted steering device for a vehicle comprises a two-part steering column which parts are capable of limited relative angular displacement, and a hydraulic power-assistance mechanism responsive by means of a hydraulic distributor to relative angular displacement of the parts. The distributor comprises a stator having a pressure orifice connected to a hydraulic pump, a return orifice connected to a fluid reservoir, and two service orifices connected to the assisting jack. Two adjacent rotors are located within the stator and these are rotatable respectively with said two parts, the first rotor having distribution passages interacting with the stator pressure and return orifices, and the second rotor having distribution passages interacting with the first rotor distribution passages and the stator service orifices.

Abstract: Disclosed is a compact rotating hydraulic drive comprising (a) a housing, (b) a pumpshaft mounted in the housing for both linear translational and rotational movement, (c) a plurality of pumping units operated by rotational motion of the pumpshaft, (d) a valve spool mounted on the pumpshaft but rotatable relative to the pumpshaft, and (e) means selectively operative upon linear translation of the pumpshaft to rotate the valve spool back and forth between a first angular position in which the output of the pump is directed in one manner and a second angular position in which the output of the pump is directed in another manner.

Abstract: The invention relates to a power-assisted steering device for a vehicle, of the kind comprising a steering wheel and steering column coupled to a steering device such as a rack and pinion arrangement, the auxiliary assisting means being hydraulically operated and including a hydraulic cylinder acting on the rack. The steering column comprises two parts which are capable of limited angular displacement in response to steering movements, and the assisting device has a fluid distributor which is sensitive to this angular displacement. This distributor comprises an axially-stacked assembly having a first stator, a first rotor plate integral in rotation with one of the two parts of the steering column, a second rotor plate integral in rotation with the other part of the steering column, and a second stator, the rotor plates having a series of hydraulic passages for feed and return of the pressurized hydraulic fluid.

Abstract: An improved power steering device which has a pinion shaft connected with a steering wheel, a rack rod which is connected with steerable wheels and whose rack is in mesh with the pinion of the pinion shaft in the gear box, a power cylinder for hydraulically actuating the rack rod, and a changeover valve for selectively connecting the first and second hydraulic chambers of the power cylinder with the hydraulic pressure source and the oil reservoir. The pinion shaft is rotatably supported in the oscillating cage which is rotatably mounted on the gear box in a manner such that the axis of the oscillating cage is offset a certain distance from the axis of the pinion shaft, whereby the oscillating cage rotates about its axis when the steering torque is applied to the pinion shaft. The oscillating cage is connected with the changeover valve so that the latter is actuated by the rotary movement of the oscillating cage.

Abstract: The invention relates to a hydrostatic steering device comprising a servo-motor operable in dependence on direction and a control device having connections for a pump, a tank and the servo-motor as well as a valve arrangement which influences the flow of pressure medium from the pump to the servo-motor and from the latter to the tank and having two valve members which are relatively movable against the force of a neutral position spring depending on the comparison of the adjustment of a steering element and the follow-up motion of a metering motor.

Abstract: A power steering apparatus for a vehicle comprising a valve housing provided with a rotary type valve body rotatable in one direction or another by a turning operation of a steering shaft. An oil supply port is connected to an oil pressure pump that is selectively connected to either of one or another of cylinder ports connected to respective left and right chambers of a power cylinder. The valve body is provided with an intermediate partition plate extending into an oil pressure reaction chamber in the valve housing to divide the chamber into areas on opposite sides of the partition plate. The resultant pair of areas extend respectively on either side in the turning direction of the valve body, and the respective areas are connected to one or the other of the cylinder ports.

Abstract: A hydraulic fluid system including fluid pressurizing means, such as a pump, and pressurized fluid utilizing means, such as a hydraulic motor, interconnected by flexible hose lines formed of material having cross-linked chlorinated polyethylene containing 25%-50% chlorine by weight as a prime constituent. The cross-linked chlorinated polyethylene material comprises, by weight, 30%-70% of the hose rubber material, and a hose constructed in accord with the invention has unusual resistance to high temperatures, flexing, high pressure and chemical corrosion.

Abstract: A rotary plug steering valve of the worm gear type for auxiliary power steering of motor vehicles is provided with a rotary plug valve and a coacting valve sleeve including means for flow passage of return hydraulic fluid to a servomotor via an inner ported sleeve disposed within the valve plug, which sleeve also serves as an alignment and bearing member for the valve plug. The advantage achieved by thus providing additional serial flow control edges between the rotary plug and a return connection via the inner sleeve is the reduction of hissing flow noises in steering operations, by a throttling of return oil flow during the relative rotation of the valve plug and the inner sleeve. This reduces the cross section of return oil flow passage, but causes no throttling in neutral position of the valve for straight ahead steering when respective passages of the valve plug and inner sleeve are in full register.

Abstract: An operating valve assembly for a power steering unit comprises inner and outer sleeves in sliding contact with each other and relatively rotatable in response to the twisting of a torsion bar corresponding to a steering load. The outer sleeve is formed in its inner circumferential surface with a plurality of recesses circumferentially spaced apart and having circular opening edges, which recesses are alternately connected to a pump and a drain chamber. The inner sleeve is formed in its outer circumferential surface with grooves establishing communication between adjacent ones of the aforesaid recesses. The outer sleeve is formed with apertures opening into the respective grooves, with the apertures being alternately connected to one or the other of the power cylinder chambers. The operating valve assembly is inexpensive and easy to manufacture.

Abstract: A control member for supplying a pressure responsive device with pressurized fluid in response to an input signal. The control member has a housing with a chamber therein. The chamber is connected to a source of pressurized fluid through an entrance port, to a pressure responsive device through first and second operational ports and to the surrounding environment through an exit port. A lever located in the chamber has a bore therein that is connected to the entrance port to define a flow path for the pressurized fluid through the chamber. Depending on a desired operation of the pressure responsive device, an input signal is applied to the lever to bring the bore into communication with one of the first and second operational ports to allow pressurized fluid to flow to the pressure responsive device while the other operational port is connected to the surrounding environment through the chamber.

Abstract: A hydrostatic steering controller including a pair of valve members which are relatively movable in opposite directions from a neutral position to a pair of operating positions to control flow between a fluid pressure source and a hydraulic steering motor. In each of the operating positions the valve members include interfacing surfaces which define part of a first passage directing high pressure fluid to the steering motor and a second passage directing low pressure fluid from the steering motor to a reservoir. The interfacing surfaces of the valve members create a pressure dam between the first and second passages when the valve members are relatively moved by a predetermined amount away from the neutral position and to an operating position. The pressure dam minimizes leakage between the first and second passages. The pressure dam is created in a pressure dam groove formed in a surface of one of the valve members.

Abstract: An improved power steering device which has a pinion shaft connected with a steering wheel, a rack rod which is connected with steerable wheels and whose rack is in mesh with the pinion of the pinion shaft in the gear box, a power cylinder for hydraulically actuating the rack rod, and a changeover valve for selectively connecting the first and second hydraulic chambers of the power cylinder with the hydraulic pressure source and the oil reservoir. The pinion shaft is rotatably supported in the oscillating cage which is rotatably mounted on the gear box in a manner such that the axis of the oscillating cage is offset a certain distance from the axis of the pinion shaft, whereby the oscillating cage rotates about its axis when the steering torque is applied to the pinion shaft. The oscillating cage is connected with the changeover valve so that the latter is actuated by the rotary movement of the oscillating cage.

Abstract: A gear assembly: a gear assembly which is used in a power assisted steering system of a vehicle.The gear assembly comprises a piston (1) within a cylinder (2), the piston (1) being axially displaceable in response to an input shaft (4). The piston (1) is axially rotatable by means of a track (18) and track follower (19) in response to axial displacement. Splines (40) on the piston (1) intermesh with teeth (42a) of a take off part (42) which is laterally spaced and in side by side relationship with the piston. By rotation of the piston (1) an output shaft (44) of the take off part (42) is rotated. In a modification of the take off part instead of being in side by side relationship is an extension of the piston and the track is of variable curved portions.

Abstract: Precise control over outlet pressure as a function of valve position is obtained for operation of a servomotor by a rotary plug valve journaled at opposite ends in a control bushing having conduit channels in fluid communication with passage grooves in the plug valve to form a plurality of parallel flow paths between a pressure inlet and two directional outlets to the servomotor. The edge formed on the plug valve by a passage groove in only one of the parallel flow paths to each of the outlets is beveled to improve valve control precision.

Abstract: An improved power steering valve has a sleeve which circumscribes an inner valve member. An end mill or other rotary cutting tool is utilized to form axially extending grooves inside the valve sleeve. When the end mill is forming the grooves inside the valve sleeve, the axis of rotation of the end mill extends at an acute angle relative to the central axis of the valve sleeve. This results in a groove being formed with axially sloping end surfaces. In order to tend to maximize the compactness of the construction of the valve sleeve, fluid passages or holes are drilled along a sloping path from annular grooves on the outside of the valve sleeve to the sloping end surfaces of the axial grooves inside the valve sleeve. In addition, the compact construction of the valve sleeve is further promoted by forming some of the annular grooves with sloping bottom surfaces so that these grooves are relatively deep.

Abstract: An assisted steering device for a vehicle has a steering column in two parts which are capable of limited relative angular play, permitting angular offsetting of the parts under the effect of the steering wheel. This enables two rotor discs, movable respectively with the two parts, to be offset relative to each other. These discs are located between two stators formed with annular grooves, and one of the discs has a circular series of passages which extend over a mean radius the value of which is between the values of the mean radii of two circular series of passages provided in the other disc.

Abstract: Relatively dispaceable valve elements of a pressure controller for a vehicle steering system provided with radial bore type valve passages having two different flow area dimensions to regulate the pressure of fluid supplied to a servomotor in response to displacement of the valve elements to an operating position from a neutral position in which the valve passages establish a short circuit flow path between the pressure source and a low pressure outlet. Flow through the short circuit passages in the valve elements are blocked in sequence during displacement of the valve elements to the operating position by sequential closing of flow passages in one of the valve elements.

Abstract: A digital servovalve control system employs a stepper motor to rotate the input shaft of a servovalve. The servovalve has no feedback shaft; feedback in the control system is provided exclusively by a digital encoder connected to the load output to indicate changes in its position. The encoder output is compared with a command signal in a digital controller circuit that generates and transmits pulses to the stepper motor in response to the difference between the command and feedback signals. The control system includes means for keeping track of the null position of the servovalve so that the digital controller can always accurately respond to the signals it receives.The servovalve used with the control system includes a valve spool that rotates with rotation of the input shaft, thereby providing a wiping action only afforded in the prior art by rotation of a feedback shaft.

Abstract: A controller for controlling fluid flow from a source to a motor, such as the steering motor of a motor vehicle. The controller includes a metering section and a control valve section comprising a stacked assembly of plate valve members which control flow and, along with the metering section, define the outer periphery of the controller, and minimize the need for complex cast housing members. The controller is compact and yet is constructed to respond to an input signal from an input shaft to direct needed flow from the source to the primary steering motor, and excess flow to an auxiliary motor. The controller is also characterized by a unique spring centering mechanism which applies a spring centering force to the assembly of plate valve members. Additionally, the controller is characterized by a special seal arrangement for resisting leakage of high pressure fluid about the input shaft, and by structure for forming pressure dams to resisting leakage of metered fluid.

Abstract: An otherwise conventional multi-way booster steering control rotary valve plug is provided with needle bearings at both ends of the grooved valve core, i.e., the rotary valve plug, in order to maintain it exactly centered radially within the coacting grooved valve sleeve i.e., a worm shaft in the present instant. This has been found to obviate heavy friction due to buildup of pressure on one side of the valve plug causing eccentricity within the valve worm shaft, such eccentricity causing these components to contact at the opposite side. The arrangement maintains radial clearance within very small limits to preclude significant oil leakage between the components and permits smooth rotary operation.

Abstract: Hydraulic servo steering gear having a cylindrical, double-acting working piston connected to a steering shaft by a rack-and-sector gear connection, especially for motor vehicles comprises a piston-and-sleeve type control mechanism arranged in the working piston. The cylindrical outer surface of the sleeve of the control mechanism is fitted loosely, with a radial gap, in the seat formed therefor in the double-acting working piston. The control sleeve is secured against axial and angular displacement.

Abstract: A control valve assembly having relatively displaceable valve elements through which control passages establish fluid flow paths to a steering servomotor for supply of metered fluid to the pressurized side of the servomotor and exhaust of fluid from the contracting side to an internal low pressure space in the valve assembly. The control passages in the valve elements are protectively located between supply passages under full pump pressure to prevent loss of fluid as a result of leakage from the control passages.

Abstract: A hydraulic rotary distributor comprising two rotary members respectively connected to an input shaft and to an output shaft, said members controlling through their relative angular position the supply of pressurized fluid to a hydraulic power-assistance motor. According to the invention, there are provided, in addition to the usual working chambers, additional reaction chambers which are fed with the same fluid pressure as the corresponding working chambers, the pressure in said reaction chambers being however limited to a predetermined maximal value thanks to devices automatically controlling the communications between said working and reaction chambers. For use particularly in power steering mechanisms for automotive vehicles.

Abstract: A controller for fluid pressure operated devices such as vehicle power steering systems. The controller is of the type having a primary, rotatable valve member and a follow-up valve member and including a fluid meter having a metering member coupled to the follow-up valve member. The valving defines a central reference plane perpendicular to the axis of rotation of the valving and the various ports and passages defined by the primary and follow-up valve members are generally oppositely and equally disposed about the central reference plane. This valving symmetry reduces internal leakage and steering wheel precession. The controller includes a load signal circuit, including a pair of load sensing grooves oppositely and equally disposed about the central plane.

Abstract: A servo valve controls the rate and direction of flow of a hydraulic fluid from a fluid power system to impart reciprocating motion to the piston of a hydraulically driven motor. An outer sleeve member of the servo valve has entry and exit ports connected to the source of fluid power and motor control ports connected to the hydraulically driven motor. A slider member is positioned within a cylindrical opening through the sleeve member and includes fluid chambers within the slider for alternating the direction of fluid flowing to the hydraulically driven motor by rotating the slider member. The rate of fluid flow is controlled by the lateral movement of the slider within the sleeve member.

Abstract: The invention relates to a hydraulic control system for a vehicle steering system or the like. The system includes two hydraulic cylinders each having a piston and a piston rod extending through one end thereof with the rod side of each piston having a smaller pressure area than the opposite side thereof. The pistons are mechanically interconnected by their piston rods. Each of the cylinders has first and second ports respectively at the nonpiston and piston ends thereof. There is a source of fluid pressure and an exhaust tank and a separate valve unit for each of the cylinders. A valve operating unit includes a steering wheel for operating the valve units in unison. The valve units have passages arranged so that for turning in either direction the first and second ports of one cylinder and the second port of the other cylinder are connected to the pressure source. At the same time the first port of the other cylinder is connected to said exhaust tank.

Abstract: The invention provides a pressure flow control valve for a booster steering system which effects an extended traverse of movement of concentric coacting valve sleeves relative to each other by a combined axial and rotary movement of the inner sleeve in order to smooth out the flow under control in pressurizing a servomotor, thus achieving an improved, or flatter, regulation curve characteristic, wherein a safe road reaction resistance to steering is effected, and wherein undesirable pressure fluctuations in the system are minimized as compared with prior art valving to reduce compressional vibration in the hydraulic system.

Abstract: A fluid controller is disclosed of the type including a primary valve member, and a follow-up valve member. The controller includes a load signal port and a load signal chamber. Fluid is communicated from the inlet port to the load signal chamber, and the valve members define a neutral orifice communicating between the load signal chamber and the return port when the valving is in neutral. The valving defines operating orifices communicating fluid from the load signal chamber to the main fluid path, downstream of the main flow control orifice, when the valving is shifted away from neutral. The operating orifices have a smaller orifice area when the valving approaches maximum deflection. The result is a substantially higher differential operating pressure, and a higher flow rate than would otherwise be possible at that particular valve deflection.

Abstract: A rack and pinion power steering gear is disclosed which includes a manifolding arrangement to eliminate external fluid connections between the power steering valve and the cylinder. The manifolding arrangement includes a tube which is received within the steering housing. The diameter of the tube is less than the diameter of the housing in which the rack is received so that an annular fluid passage is defined between the outer circumferential surface of the tube and the inner circumferential surface of the housing. The annular passage communicates fluid the entire length of the rack mechanism, so that fluid may be selectively admitted to opposite sides of the piston depending upon the direction which the vehicle wheels are turned. The manifolding mechanism further includes a sleeve which extends into the tube and which is provided with passages extending therethrough to communicate fluid pressure to the other side of the piston.

Abstract: A controller for fluid pressure operated devices such as power steering systems. The controller is of the type having a primary, rotatable valve member and a follow-up valve member and including a fluid meter having a metering member coupled to the follow-up valve member. The valving defines a central reference plane perpendicular to the axis of rotation of the valving, the primary valve member defining a pair of meter grooves oppositely and equally disposed about the plane. The follow-up valve defines pressure porting adjacent the plane and connected to the fluid inlet port.

Abstract: A closed-center controller is disclosed, especially of the type utilized in hydrostatic power steering systems. The controller includes valving which, in the neutral position, defines a bypass passage communicating inlet fluid through the interior of the hollow, primary valve member to the tank port of the controller. The bypass passage includes a variable bypass orifice having a maximum flow area in the neutral position of the valving and decreasing to zero as the valving is displaced from the neutral position. The variable bypass orifice permits the passage of just enough fluid, typically in the range of about 0.25 gpm to about 0.5 gpm, to minimize the temperature difference between the controller valving and the remainder of the hydraulic system, thus minimizing the possibility of thermal seizure of the valving within the controller.

Abstract: A rack and pinion steering gear mechanism for use with the dirigible wheels of a road vehicle comprising a steering gear pinion adapted to be connected to a vehicle steering linkage, a power rack engageable with the pinion and adapted for reciprocating linear motion, said rack including a power piston mounted within a power cylinder which define a pair of opposed pressure chambers, a steering shaft connected yieldably to the pinion by a torsion shaft, fluid pressure control valve means including relatively displaceable parts forming in part fluid connections between a pressure source and each of said pressure chambers, one valve part being connected to the pinion and the other part being connected to the steering shaft whereby distribution of working pressure to the pressure chambers is dependent upon the direction of torque applied to the steering shaft, the magnitude of the pressure buildup in the pressure chambers being proportional to the degree of displacement of the steering shaft relative to the pinion

Abstract: A system for supplying pressurized fluid from a pressure source to a fluid-operated power device comprises an actuator, a sole first pressure conduit leading from the source to the actuator and at least two second pressure conduits leading from the actuator to the power device. The actuator comprises a cylinder and a piston arranged for simultaneous reciprocation and rotation in the cylinder. The reciprocation of the piston is effected by the fluid pressure introduced periodically into the cylinder through the first pressure conduit. The rotation of the piston is effected by the cooperation of a pin affixed to the cylinder wall with a helically extending groove in the cylindrical piston face.

Abstract: A four-way fluid flow control valve for selectively interconnecting opposite sides of a fluid motor with a source of fluid pressure and a low pressure return line for driving the motor in opposite directions. A clevis-like, bifurcated metering member has opposed, cup-shaped elements at its bifurcated end which are shiftable across opposed, flat surfaces to produce the desired fluid flow interconnections. The cup-like elements present fluid transfer zones for selectively interconnecting different fluid flow passages.

Abstract: A controller for fluid pressure operated devices such as hydrostatic power steering systems. The controller is of the type having a primary, rotatable valve member and a follow-up valve member, and further comprising a fluid meter including a metering member coupled to the follow-up valve member. The controller is of the 5-port type, having a load signal port for communicating a steering load signal and maintaining a constant pressure drop across the main control orifice of the controller. The primary and follow-up valve members define a central reference plane oriented generally perpendicular to the axes of rotation of the valve members and the various ports and passages defined by the valve members are arranged in somewhat of a mirror image of each other about the reference plane.

Abstract: A controller for fluid pressure operated devices such as power steering systems. The controller is of the type having a primary, rotatable valve member and a follow-up valve member, the valve members defining a neutral position. The follow-up valve member is coupled to the primary valve member for limited movement relative to the neutral position. The controller further comprises a fluid meter including a metering member for measuring the volume of fluid passing therethrough, the metering member being coupled to the follow-up valve member. The controller has an inlet port and first and second control fluid ports which may be connected to the opposite ends of the power steering cylinder.