Abstract: Conventional steering systems of this type have the disadvantage that the dynamic load signal flow is lossy which has a negative effect on the energy efficiency. Another disadvantage arises in steering systems with a closed-center design. When the steering cylinder is pulled by an external force, the steering cylinder moves in advance of the apportioned steering flow. In the present novel steering system, the adjusting angles of the primary adjustable throttles (12, 13, 14, 15, 16, 17) are matched in a novel way, so that in a steering range where the steering rotational speed is limited, the load signal flow is used for actuating the steering system. In this phase, the steering system then operates according to the open-center principle.

Abstract: A torque generator steering device (11) including a gerotor gear set (17) disposed adjacent an end cap (15) and having the input shaft (21) extending through the end cap and through the orbiting and rotating star member (31). The valving of the device, including a spool valve (37) and a sleeve valve (39), is disposed on the side of the gerotor gear set (17) toward an output shaft (23). Preferably, the input shaft (21) is integral with the spool valve (37), and the sleeve valve (39) is integral with the output shaft (23). A coupling arrangement (77) is provided to translate orbital and rotational movement of the star (31) into rotational follow-up movement of the sleeve valve (39). The result is a very short, compact torque generator having substantially reduced backlash between the input shaft (21) and the output shaft (23).

Abstract: A fluid controller (17) of the dynamic load sensing and flow amplification type, and including a main fluid path (35,39) having a main variable flow control orifice (43), and a fluid meter (37). Dynamic signal fluid enters a load sensing port (29) of the controller and flows through the fluid meter (37) before the main orifice (43) opens, as the controller valving is displaced from neutral to an operating position (FIG. 5). In accordance with the invention, in addition to the normal load sensing drain orifice (LD1) which closes just about the time the main orifice (43) opens, there is provided a load sensing drain orifice (LD2) which remains open somewhat after the main orifice (43) and an amplification orifice (50) open, to prevent build-up of pressure upstream of the fluid meter (37). As a result, there is no flow through the fluid meter (37) until after the amplification orifice (50) opens, and the flow amplification capability appears to the operator to come on instantaneously.

Abstract: A hydraulic control arrangement is disclosed having a directional valve, a metering pump unit which has two metering pumps which are connected hydraulically in parallel and are operable mechanically in parallel, and a shut-off valve in a hydraulic connection between the two metering pumps, a pump connection and a tank connection which are connected to the metering pump unit by way of the directional valve, and also two working connections which are connected to the directional valve, a control inlet of the shut-off valve being connected to the pump connection. Such a control unit should be constructed to be user-friendly, especially for emergency operation. For that purpose, a safety valve arrangement is arranged between the control inlet of the shut-off valve and the directional valve.

Abstract: A fluid controller (11) of the type comprising a rotatable spool valve (31) and a relatively rotatable follow-up sleeve valve (33), in which fluid flows through a fluid meter (15) of the type in which a star member (39) orbits and rotates as fluid flows through the meter (15). The rotation of the star (39) is transmitted to the sleeve valve (33) to provide follow-up movement thereto. In accordance with the present invention, the star (39) defines a set of internal teeth (41) and a terminal portion (42) of the sleeve valve (33) extends axially into the star and defines a set of external teeth (43), in driven engagement with the internal teeth (41). As a result of the follow-up arrangement of the invention, the need for the conventional drive shaft and transverse pin is eliminated, the spool and sleeve can have smaller diameters, and the overall fluid controller can be smaller, less complicated, and less expensive.

Abstract: A steering system having a first auxiliary branch line (23, 24) connecting a main line (6) to a return port (12); with a load line (22) connecting the first auxiliary branch line to a load port (13) and dividing the first auxiliary branch line into first (24) and second (23) flow paths. The main line includes an adjustable input throttle (20). The first flow path (24) includes an adjustable load throttle (27) and a second throttle (26) in series. The adjustable input throttle and the adjustable load throttle act in a same direction. The purpose of this control circuit is to raise the load port pressure level, so as to prevent relatively high power losses.

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 fluid controller (15) for use with an unequal area cylinder (25) having a rod end area A and a head end area B. The controller valving (27) includes, in one embodiment, a flow amplification path (101) for only one direction of steering. In another embodiment, the controller valving (27) includes flow amplification in both directions of steering, but with the ratios being different. In either case, the ratio of flow to the head end to flow to the rod end equals the ratio B/A, whereby the fluid controller requires the same number of turns, lock-to-lock, for either direction of steering.

Abstract: A fluid controller (17) having a housing (21) and valving including a spool (41) and a follow-up sleeve (43). The spool and sleeve define a central reference plane (RP) with the housing having two annular chambers (61, 62) receiving pressurized fluid from an inlet port (23). One of the annular chambers (61) communicates pressurized fluid to the main flow control orifice (A1) in a left turn, and to the flow amplification orifice (AQ) in a right turn, while the other annular chamber (62) communicates pressurized fluid to the main flow control orifice (A1) in a right turn, and to the flow amplification orifice (AQ) in a left turn. A check valve (103,105) is associated with each of the annular chambers, such that one check valve (103) is an inlet check in a right turn and a reverse flow prevention check while manually steering in a left turn, whereas the other check valve (105) is an inlet check in a left turn and a reverse flow prevention check while manually steering in a right turn.

Abstract: A fluid controller (17) is disclosed of the type including a relatively rotatable valve spool (95) and valve sleeve (97) which define a series of variable control orifices (71-76) during normal steering operations. Fluid flow to a control port (27) is controlled by a variable control orifice (74). During small steering corrections, at relatively small valve displacements, the present invention provides an additional variable control orifice (155), which opens before the control orifice (74) opens. A form of check valve (153) is in series with the additional orifice (155), and downstream thereof, to prevent reverse flow from the control port (27) through the controller. The invention is especially beneficial in controllers of the dynamic load signal type including a load signal drain orifice (76) which is open to the system reservoir (R) at the relatively small displacements.

Abstract: A steering control system for an autonomous machine has a manual steering control valve for directing fluid from a pump to either a head end chamber or a rod end chamber of a hydraulic steering actuator. In one embodiment, an electrically actuated steering valve device is disposed in series flow relationship between the pump and the manual steering control valve and is operative to direct fluid from the pump to the head end and rod end chambers. In another embodiment, a electrically actuated device mechanically actuates the manual steering control valve for steering the machine.

Abstract: A fluid power apparatus is connected to a pressurized fluid supply and a conventional helm pump controlled by the helm of a vessel to shift the rudder. The apparatus comprises an actuator cylinder connectable to the rudder, and a servo cylinder and a main valve connected to the helm pump to pass fluid therebetween and between the actuator cylinder. The actuator cylinder and servo cylinder have respective bodies and piston rods, and portions of the servo cylinder and actuator cylinder are connected together for concurrent simultaneous movement along respective longitudinal axes. Valve shifting structure is responsive to a change in fluid signal from the helm pump applied to the servo apparatus. Fluid diverting structure is responsive to a threshold supply pressure so as to actuate the valve to stop flow of supply fluid when supply pressure drops below the threshold pressure.

Abstract: An auxiliary power source, for example, an electric motor, supplies the power assist for a steering unit via a worm gear (15, 16). The worm gear (15, 16) drives clutch hubs (22 and 23) in the opposite rotational directions. The auxiliary power can be transferred to a driven shaft (3) via a common clamping sleeve (27) that can be expanded polygonally by two rows of clamping bodies (28 and 30) into one or the other clutch hubs (22 or 23). The clamping sleeve (27) is slitted into functional segments (A and B). Depending on the direction of rotation of the steering spindle (1), one or the other functional segments (A or B) of the clamping sleeve (27) is always active. The clutch units (2) run in a lubricant so that there is little wear and tear. This steering system can be made at reasonable cost and takes little space for installation.

Abstract: A torque generator steering device (10) is disclosed of the type including a gerotor displacement mechanism (19) and valving (9), by the rotation of an input shaft (1) results in a hydrostatic power assist to an output shaft (2). In parallel with the power assist path, the input shaft (1) is connected by a torsion bar (15) to a connecting shaft (3) which, in turn, is connected to the output shaft (2). The connections between the torsion bar (15) and the connecting shaft (3), and between the connecting shaft (3) and the output shaft (2) are substantially zero backlash mechanical connections, thus providing a main torque transmitting path in parallel with the power assist path. Below a predetermined level of input torque, rotation of the input shaft (1) results in an immediate and corresponding rotation of the output shaft (2), thus providing a manual steering mode.

Abstract: A flow amplifier (1) with an inlet (4) and an outlet (5) is provided, between which a first branch (6), through which a flow of a fluid to be amplified is flowing, with a first throttling device (8), the throttle resistance of which is adjusted in dependence on the pressure across and by the flow rate through the first throttling device, and a second branch (7) with a second throttling device (11), the throttle resistance of which is adjusted in dependence on the throttle resistance of the first throttling device. In a flow amplifier of that kind, the amplification factor is intended to be made independently of pressure losses in the generation of the flow to be amplified. For that purpose, at least one pressure-divider (14, 15; 17, 18) with a central take-off point (16; 19) is provided, which is supplied by a pressure difference between inlet (4) and outlet (5), the pressure at the central take-off point (15, 19) controlling the flow rate through the second throttling device (11).

Abstract: A hydrostatic power steering system is provided of the type including a steering control unit (3) operated by an input such as a steering wheel (1) to control flow from a source (8) to a steering cylinder (7). The source is operated in response to an electrical signal from a controller (82), controlled by a sensed pressure at a pressure detection port (64). The pressure at the port (64) is communicated from the main fluid path of the steering control unit (3), downstream of the fluid meter (18) when the spool (21) and sleeve (22) are relatively displaced. In systems in which the system reservoir (R) is at an elevated ("regulated tank") pressure, the pressure detection circuit is drained through a variable orifice (70) to a drain port (66), which is in communication with a sump (S) maintained at substantially atmospheric pressure. As a result, the steering system responds at a lower steering pressure, and the initial steering is smoother.

Abstract: An improved fluid controller (15) is provided having both rotary valving (47) actuated by the steering wheel (17), and axial valving (49) controlled by an electro-hydraulic valve (113) in response to a correction signal (31). In one embodiment, both the rotary valving and the axial valving are achieved by a primary valve member (63) and a follow-up valve member (65), and both the rotary and axial valving can be actuated simultaneously. Also disclosed is a logic control system for closed-loop control of the electro-hydraulic valve, whereby performance problems such as self-steering, wander, drift, and others are substantially eliminated.

Abstract: A steerable trailer is described which includes a coupling detector for detecting a coupling angle, a trailer wheel steering angle detector for detecting a trailer wheel steering angle, and actuators for steering the trailer wheels. A controller is provided for calculating and memorizing a travel direction of a coupling point at a location in response to signals transmitted from each of the detectors. The controller transmits output signals to the actuators to align a travel direction of a rear end of a trailer with the memorized direction of the coupling point when the rear end of the trailer reaches the location. The controller calculates and memorizes the travel direction of the coupling point at plural, discrete locations along the path of travel of the trailer. The steerable trailer may be connected to a tractor to provide a vehicle.

Abstract: A fluid power apparatus is connected to a pressurized fluid supply and a conventional helm pump controlled by the helm of a vessel to shift the rudder. The apparatus comprises an actuator cylinder connectable to the rudder, and a servo cylinder and a main valve connected to the helm pump to pass fluid therebetween and between the actuator cylinder. The actuator cylinder and servo cylinder have respective bodies and piston rods, and portions of the servo cylinder and actuator cylinder are connected together for concurrent simultaneous movement along respective longitudinal axes. Valve shifting structure is responsive to a change in fluid signal from the helm pump applied to the servo apparatus. Fluid diverting structure is responsive to a threshold supply pressure so as to actuate the valve to stop flow of supply fluid when supply pressure drops below the threshold pressure.

Abstract: A hydraulic power steering apparatus (10) comprises a rotatable input member (31), a rotatable output member (130), and a housing supporting (11) the input member (31) and the output member (130) for rotation about an axis (45) relative to each other. A hydraulic control valve assembly (30) in the housing (11) includes a valve core (40), a valve sleeve (41) and a plurality of hydraulic seals (120-126) which block leakage of hydraulic fluid from the valve assembly (30). The hydraulic power steering apparatus (10) further includes an elastomeric damping ring (200) extending circumferentially between the valve core (40) and the valve sleeve (41). The elastomeric damping ring (200) damps vibrations of the valve core (40) relative to the valve sleeve (41), and thereby attenuates noise in the apparatus (10).

Abstract: The control arrangement may be used for vehicles or in other steering systems and includes a steering motor that is adjusted as a function of hand operated steering mechanism, the steering mechanism controlling a directional section and a metering motor section. The directional section is fluidly connected between the steering motor and both of a tank and the metering motor section. A pump is connected between a tank and the metering motor section. The one sides of electromagnetic plus and negative valves are fluidly connected between the fluid connection of the metering motor section and the directional section while the opposite sides are respectively connected to the connection of the pump and the metering motor section and the connection of the directional section to the tank. A processing device for controlling the valves is provided for sensing the steering angle error. The control arrangement provides a simple structural arrangement to compensate for leakage.

Abstract: A hydraulic steering system is provided including a hydraulic steering unit (3) provided with a housing (6) having an inlet port (7), an outlet port (8), and a pair of control ports L and R. A measuring part (fluid meter) (19) includes an internally-toothed gear member (21) disposed in the housing, and an externally-toothed gear (22) disposed within the gear (21) to be in engagement therewith and have orbital and rotational movement therein. A changeover valve (9) controls the flow of fluid to and from the ports and through the measuring port. An input shaft (13) actuates the changeover valve (9), and an output shaft (24) is actuated by the torque out of the measuring part (19). A steering wheel (1) is connected by means of a steering column (2) to the input shaft (13) of the steering unit (3).

Abstract: A power steering device for a motor vehicle whereby when the vehicle is under a high or middle speed movement, the slide torque is controlled to a relatively low constant level irrespective of the turning of the steering wheel. The device includes a hydraulic pump for producing a hydraulic pressure; a power cylinder powered by the hydraulic pressure for producing a force to assist the steering job; a hydraulic valve for controlling the hydraulic pressure supplied to the power cylinder, the hydraulic valve including a valve shaft and a valve body; a chattering protection seal associated with the hydraulic valve to assure a concentric rotation of the valve shaft relative to the valve body with an assistance of hydraulic pressure applied thereto; and an electronically controlled solenoid valve.

Abstract: A fluid controller (11) is disclosed of the type including a housing (13), a fluid meter (17), a primary (spool) valve (35), and a follow-up (sleeve) valve (37). An inlet port (23) is in communication with a series of fluid ports (85), and operating ports (91L and 91R) are in communication with the cylinder ports (27 and 29). Rotation of the spool relative to the sleeve causes axial displacement of the sleeve as a result of the configuration of a pin opening (55) in which a drive pin (53) is disposed. After a certain amount of axial movement of the sleeve, the various ports (85,91L,91R) begin to communicate with a pair of meter grooves (67R and 67L) and a tank groove (71R), respectively, to define variable axial flow control orifices (A1a,A4a,A5a).

Abstract: A hydrostatic power steering device (11;111) is provided of the type including a primary, spool valve (35;135), and a follow-up, sleeve valve (37;137). During normal operation, relative rotation of the spool and sleeve define one or more variable flow control orifices (A1A5; AN; A1) and these orifices have a first area versus deflection relationship when the sleeve is biased to its first position (FIG. 5; FIG. 10). The sleeve may be moved toward a second position (FIG. 6; FIG. 11) in response to an input (95, 99) other than rotation of the vehicle steering wheel. In the second axial position of the sleeve, the flow control orifice has a different area versus deflection relationship, the difference providing a useful steering or ancillary function.

Abstract: A fluid controller (11) is provided of the type which controls the flow of fluid from a source to at least a first fluid pressure operated device. The controller is of the type including a primary, spool valve (39;39') and a follow-up sleeve valve (41;41'). The spool and sleeve are of the type in which relative rotation therebetween defines a main fluid path through a fluid meter (23), and in which axial movement of the sleeve (39') defines a parallel fluid path (FIG. 7) or an auxiliary fluid path. A neutral centering spring arrangement is provided including at least one compression spring (101) having its ends disposed in engagement with seat members (97,99) to bias the spool and sleeve toward their neutral rotary position.

Abstract: A controller (15) is provided of the type which may be utilized in a hydrostatic power steering system. The controller includes a fluid actuated displacement mechanism (21) comprising a stationary ring (47) and a moveable star (49) to meter fluid flow through the controller valving (19). A plug member (105) is operable to apply a braking force to the moveable member (49) and it cooperates with the housing (27) to define a fluid chamber (109). The housing defines a fluid passage (111, 113, 117, 119) between the fluid chamber and the controller valving (19). The controller valving in the housing defines a drain passage (95, 99, 97) to drain the fluid chamber (109) when the controller valving is in its first operating position (FIG. 4 ) and to restrict the drain and allow pressure to increase in the fluid chamber (109) when the valving is approaching its maximum displacement position (FIG. 5).

Abstract: A hydraulic reaction device of a power steering apparatus includes a vehicle-speed responsive pump, a reaction plunger, a hydraulic reaction chamber, a path, and a variable control unit. The vehicle-speed responsive pump has a pressure oil discharge flow rate which changes in accordance with a vehicle speed. The reaction plunger selectively constraining relative pivotal displacement between input and output shafts constituting a rotary flow path switching valve of the power steering apparatus. The hydraulic reaction chamber receives the pressure oil from the pump to apply a reaction oil pressure to the reaction plunger. The path is arranged to connect the hydraulic reaction chamber to a tank. The variable control unit (a variable throttle portion 37 of a reaction oil pressure control valve 11) for variably controlling a flow rate of the pressure oil flowing through the path.

Abstract: A fluid controller (15) is provided of the type having a primary valve member (53) and a follow-up valve member (55). The controller includes a housing (41) defining main fluid ports (27,29) connected to a steering cylinder (19), and also defines auxiliary fluid ports (31,33), connected to an auxiliary fluid motor (21). The spool and sleeve cooperate with the housing to provide main control valving (35) controlling the flow of fluid to the steering cylinder in response to relative rotation of the spool and sleeve, and auxiliary control valving (35), controlling the flow to the auxiliary motor in response to axial motion of the sleeve, relative to the spool and housing. By performing both the main and auxiliary valving in the spool and sleeve, the main valving (35) is automatically given priority over the auxiliary valving (37), without the need for any expensive, complicated controls or interface between the two types of valving.

Abstract: The hydraulic system for a servo steering of a motor vehicle, incorporates a main valve mechanism producing the assistance pressure (Pa) applied to a hydraulic assistance device (12) and including a pair of parallel fluid circuits between a source (14) of pressurized fluid and a reservoir (16), each fluid circuit comprising at least two restrictions (1,2,1',2') capable of being modulated by a rotor mechanism (10) cooperating with a stator mechanism (11), the junction point of the restrictions of each circuit being connected to a respective chamber of the hydraulic assistance device (12) and a secondary valve mechanism producing the reaction pressure (Pr) applied to the steering wheel shaft and including a second pair of parallel fluid circuits between a source (24) of pressurized fluid and a reservoir (16), each of the fluid circuits comprising at least two restrictions (3,4,3',4') capable of being modulated by the rotor mechanism (10) cooperating with stator means, the rotor mechanism (11) cooperating with t

Abstract: Neutralizer valves are useful in hydraulic steering systems to hydraulically stop the steering motion. However the known neutralizer valve arrangements will not work in load sensing hydrostatic steering systems. The subject load sensing hydrostatic steering system has a limit valve disposed in a load pressure signal signal line to normally communicate a load pressure siganl from a steering valve to a displacement controller of a load sensing variable displacement pump so that the displacement of the pump is regulated to meet the demand for pressurized fluid by the steering valve. When a pair of vehicle members reach a preselected position during a steering maneuver, the limit valve is moved to a position interrupting communication of the load pressure signal to the displacement controller causing the pump to destroke to its minimum output thereby stopping the flow of pressurized fluid to the steering valve and to a pair of steering cylinders.

Abstract: An improved fluid controller (15) is provided having both rotary valving (47) actuated by the steering wheel (17), and axial valving (49) controlled by an electro-hydraulic valve (113) in response to a correction signal (31). In one embodiment, both the rotary valving and the axial valving are achieved by a primary valve member (63) and a follow-up valve member (65), and both the rotary and axial valving can be actuated simultaneously. Also disclosed is a logic control system for closed-loop control of the electro-hydraulic valve, whereby performance problems such as self-steering wander, drift, and others are substantially eliminated.

Abstract: A fluid controller (15) is disclosed of the type including a primary, spool valve (41) and a rotatable follow-up valve member (43). The controller includes a housing (23) defining an inlet port (31), a return port (33), and control fluid ports (35 and 37). The return port is in communication with an interior chamber (33c) disposed within the spool valve (41). The controller is of the type including a fluid meter (21) through which the fluid flows as part of the main fluid path, imparting the follow-up movement to the follow-up valve member (43). Anti-cavitation check valves (95L, 95R) are disposed in the spool valve, and permit direct communication from the interior chamber of the spool into the main fluid path when the valving returns to neutral (FIGS. 3 and 5) after cavitation occurs.

Abstract: A fluid controller (11) is disclosed for controlling the flow of fluid from a source (73) to a steering cylinder (77), especially for use on large, articulated vehicles. The controller includes a fluid meter (17) and a valving arrangement including a spool (33) and a sleeve (37). The housing and the valving define a main fluid path (113) including a main variable flow control orifice (A1), and the fluid meter (17) in series flow relation between an inlet port (23) and the first control fluid port (27). In accordance with the invention, the main variable flow control orifice is formed by a first fluid passage (93R; 123L) defined by the spool, being in fluid communication with a first fluid port means (101R; 131R) defined by the sleeve. The first fluid port means extends circumferentially to provide continuous fluid communication between the inlet port and the first fluid passage of the spool, as the spool rotates relative to the sleeve from the neutral position to the first operating position.

Abstract: A hydrostatic auxiliary power steering mechanism with load-dependent performance for controlling a variable displacement pump includes an orifice for generating a pressure difference. A control valve in a valve borehole contains a movable valve piston. Orifice is formed between the discharge opening cross-section of a pressure line into the valve borehole and a central spool land provided on valve piston and reveals a cross-section that can be altered as a function of the position of the control valve. The cross-section of orifice has its smallest value when the control valve is in the neutral middle position and can be made larger by adjusting the control valve in both directions.

Abstract: A control mechanism for two consumers includes a flow divider valve (3) which is connected to a pump 2. From flow divider valve (3) springs a flow line (12) for the working flow (A) of a first adjustment device (10) such as a steering motor. Another flow line (13) of the flow divider valve (3) leads via an activation valve (14) to a second adjustment device (15). A pilot flow line (4) connected with the flow divider valve (3) via a measurement diaphragm (3A), is connected with a pilot valve (5). Pilot valve (5) can choke or entirely block the connection from the pilot flow line (4) to a nonreturn line (11) for the purpose of setting a pressure in flow line (12). For purposes of activation, pilot valve (5) is coupled with a steering valve (6) that controls flow line (12) so that both valves can be deflected together during one steering movement. A hydraulic steering unit is provided as the steering mechanism and it includes a rod-set connection from a manual steering wheel to the vehicle wheels.

Abstract: Hydrostatic auxiliary power steering devices transmit the steering power to the steered wheels via oil pressure. Such devices utilize a metering pump 5 and a steering valve 2 combined into a single unit. The metering pump distributes oil flow produced by a power steering pump 1 to a pressure operated steering power cylinder 8 under control of a steering valve 2 responsive to drive rotation of the vehicle steering wheel. The oil flow synchronizes the angle of rotation of the steering wheel with the angle of the lock of the wheels being steered. In hydrostatic systems there is a tendency to pressure oscillations. In the present invention these oscillations are minimized without occurring excessive pressure loss. The arrangement provides an inlet conduit 4 for steering, a damping valve 11 having a damping piston 12 centered by springs 13, 14 and closing off a branch conduit 6 which stops flow to the metering pump 5.

Abstract: A fluid controller (15) is provided of the type which controls the flow of fluid from a source (11) to a priority device (19) and an auxiliary device (21). The controller includes a valving arrangement (33) comprising a primary, rotatable spool valve (51), and a cooperating, relatively rotatable follow-up sleeve valve member (53). The spool and sleeve cooperate to define controller valving (35) while the sleeve and housing cooperate to define load sensing, priority flow control valving (37). In a preferred embodiment, the controller valving is defined by relative rotation between the spool and the sleeve, while the priority flow control valving is defined by relative axial movement between the sleeve and the housing. The axial position of the sleeve is controlled by fluid pressure in a pilot pressure chamber (95), and in a load signal chamber (103), the difference therebetween representing the pressure differential across a main variable flow control orifice (A1) defined by the controller valving (35).

Abstract: A hydrostatic steering device is provided with a pump connected with a reservoir, a steering valve, a controlled-volume pump that is capable of being activated by a steering wheel and with a steering cylinder. The steering mechanism has a variable working flow and a constant pilot flow, with the pilot stream flowing through a constant throttle and the pressure drop through the constant throttle serving as a control signal for the conveying flow in a pressure delivery line. The controlled-volume pump is coupled mechanically with an adjustment throttle through which the pilot flows. Between the constant throttle and the adjustment throttle lies a pressure compensator that is controlled by the adjustment throttle's differential pressure. To receive the load signal, a control line branches off between the constant throttle and the pressure compensator and leads to the pump or, in the case of a fixed displacement pump with a rear-position flow-dividing valve, to the flow-dividing valve.

Abstract: A hydrostatic power steering device is disclosed, which may be either a fluid controller (15) or a torque generator 111. The device is of the type including a housing (19;135) defining a fluid inlet port (29;113) and a return port (31;115). The device includes valve means (36;171) defining a neutral position and a first operating position. The device includes a gerotor mechanism (23;143) for imparting follow-up movement to the valve means in response to fluid flow through the gerotor, and a follow-up mechanism (49,51;183,185) transmits the follow-up movement to the valve means. The valve means defines a return fluid region (87,89,31g;205,197,157) which comprises part of the main fluid path. The return fluid region is isolated from the follow-up means and from the interior of the valving.

Abstract: A full hydraulic power steering apparatus is provided of the type including a steering unit (2) and a steering cylinder (5). Pressurized fluid is supplied to the steering unit (2) from a pump (6) and compensating valve (10) through a pressure line (8). Conduits (103, 104) communicate from the pressure line (8) to a pair of amplification ports (38, 39) through a pair of open-close valves (105, 106) and check valves (108, 109). A pair of detection members (101, 102) sense the positions of the input handle (1) and the steering cylinder (5), and a controller (100) generates electrical input signals to control operation of the valves (105, 106) to correct any short or over condition of the cylinder (5) relative to its target position as determined by the position of the input handle (1).

Abstract: A fluid controller (11) is provided of the type including a primary, rotatable spool valve (35) and a relatively rotatable follow-up sleeve valve (37). The spool and sleeve define a main fluid path in response to relative rotation, the main fluid path including flow through a fluid meter (17). In accordance with the invention, the spool and sleeve are also moveable axailly relative to each other to define a separate fluid path, in parallel with the main fluid path, the parallel fluid path preferrably excluding the fluid meter (17). Axial actuation of the spool and sleeve relative to each other may be accomplished by controlling fluid pressure in a pair of axial fluid chambers (69, 83). The control of the fluid pressure may be accomplished by any suitable electrohydraulic means (95) or hydromechanical means (181).

Abstract: An open-center fluid controller (15) is disclosed for controlling the flow of fluid to a steering cylinder (25). The controller includes a fluid meter (29) and valving arrangement (27), including a valve spool (43) and a sleeve (45), which define a main fluid path. The main path includes a fixed flow control orifice (86), a variable flow control orifice (87), the fluid meter (29), and a variable flow control orifice (89). In accordance with the invention, the spool and sleeve define an amplification fluid path (101), including a variable amplification orifice (99), in parallel with the main fluid path, and disposed to amplify the flow of fluid through the meter (29). In order to facilitate manual steering, the amplification orifice (99) reaches its maximum flow area when the spool and sleeve are in a normal operating position (FIG. 6). The amplification orifice then decreases and closes as the displacement between the spool and sleeve reach a maximum displacement (FIG. 7).

Abstract: In order to prevent kick-back at the steering element that controls a fluid steering motor, there is provided hydrostatic steering apparatus that includes a control device connected between a priority valve and the steering motor. A load pressure conduit connects an outlet of the priority valve to a junction of the control device. The priority valve includes a tapping at which there is provided fluid pressure for moving priority valve slide, two pressure distributing throttles being connected to the tapping. A check valve that opens toward the junction is provided in the load pressure conduit between one of the distributing valves and the junction. Another check valve that opens toward the junction is fluidly connected in series with a control device supply throttle between the junction and the priority valve outlet, the supply throttle and junction being in a fluid line that supplies pressurized fluid to the steering motor.

Abstract: A flow amplifier in the hydraulic steering system of a transport vehicle comprises a three-position hydraulically operated hydraulic directional control valve having a single sliding spool valve and internal hydraulic pilot lines connected, when in the crossover position, to external portholes made in a sleeve of the three-position hydraulically operated hydraulic directional control valve provided with plungers spring-loaded on their outside end faces. The flow amplifier incorporates also a pair of intensifying chokes, a air of pilot chokes, and a pair of regulating chokes made in the sliding spool valve with a possibility of varying their restriction areas along the direction of travel of the sliding spool valve.

Abstract: In general, an auxiliary system for steering a vehicle includes a power steering unit coupled to the vehicle steering wheel so that the steering unit is thereby made capable of being manually powered by a vehicle operator for providing a supply of fluid at a first pressure. Valve means is connected between the steering unit and a pressure intensification device for selectively providing motive power to the device. Actuator means is connected between the device and the steering linkage of a vehicle for steering movement of the wheels. The intensification device is powered for rotation by the fluid at the first pressure when the steering unit is manually operated. The intensification device thereby delivers hydraulic fluid to the actuator means at a second pressure for steering the vehicle during auxiliary conditions.

Abstract: A torque-generating steering device is provided for use with a pump (19) having a pressure compensator (23) for varying the output of the pump. The device includes a gerotor displacement means (43) which provides a relatively high-torque output to an output shaft (29) in response to the flow of fluid through the gerotor. A spool valve (73) and sleeve valve (75) define a fluid path (119) from an inlet port (13) through the gerotor to an outlet port (15). The fluid path includes a main variable flow control orifice (121) in series flow between the inlet and the gerotor, the orifice having a zero flow area when the spool and sleeve are in their neutral position, and a maximum flow area when the spool and sleeve are in an operating position. The device defines a load-sensing port (115) communicating with the pressure compensator (23) and with the fluid path (119), downstream of the orifice (121).

Abstract: Flow amplified control systems are useful in pilot operated steering systems. The load responsive flow amplified control system includes a directional control valve movable to an operating position to direct fluid from the operating fluid circuit through a variable orifice to a steering motor and to direct control fluid from a control fluid circuit through another variable orifice to be combined with the fluid going to the steering motor. The operating fluid circuit and the control fluid circuit are provided with fluid from a common variable displacement pump. The directional control valve is moved to an operating position by the control fluid acting thereon and is pressure compensated insofar as the flow of control fluid passing through the another variable orifice such that a substantially constant predetermined pressure differential exists across the another variable orifice.

Abstract: A fluid controller (17) is disclosed for controlling the flow of fluid to a steering cylinder (19). The controller includes a fluid meter (51) and a valving arrangement (49) including a valve spool (65) and a sleeve (67), which define a main fluid path including a main variable flow control orifice (121), the fluid meter (51), a variable flow control orifice (123), the steering cylinder (19), and a variable flow control orifice (125). In accordance with the invention, the spool and sleeve define an amplification fluid path including a variable amplification orifice (129) in parallel with the main fluid path, and disposed to amplify the flow of fluid through the meter. In one embodiment of the invention, the amplification fluid path communicates with the main fluid path upstream of the main variable flow control orifice, and at a location downstream of the fluid meter, but upstream of the variable flow control orifice (123).

Abstract: An open-center fluid controller (15) is disclosed for controlling the flow of fluid to a steering cylinder (25). The controller includes a fluid meter (29) and valving arrangement (27), including a valve spool (43) and a sleeve (45), which define a main fluid path. The main path includes a fixed flow control orifice (86), a variable flow control orifice (87), the fluid meter (29), and a variable flow control orifice (89). In accordance with the invention, the spool and sleeve define an amplification fluid path (101), including a variable amplification orifice (99), in parallel with the main fluid path, and disposed to amplify the flow of fluid through the meter (29). In order to facilitate manual steering, the amplification orifice (99) reaches its maximum flow area when the spool and sleeve are in a normal operating position (FIG. 6). The amplification orifice then decreases and closes as the displacement between the spool and sleeve reach a maximum displacement (FIG. 7).