Abstract: A steering system for an articulated vehicle has a microprocessor connected to a proportional solenoid valve which controls the direction, amount and rate of flow of hydraulic fluid to and from hydraulic articulation cylinders, which provide articulation between the frames of the articulated vehicle. A positional feedback sensor measures the angle of articulation between the frames and communicates the angle of articulation to the processor. A gear sensor monitors the gear that the vehicle is in and communicates it to the processor. A user input device allows a user to select the desired level of steering sensitivity and also allows the user to input the size of the tires installed on the vehicle. A steering device allows the operator to provide steering input and communicates electrical steering signals to the processor based on the steering input from the operator.

Abstract: A hydraulic four-wheel driving articulated vehicle comprises: a first frame, on which first axles and a first hydraulic motor driving the first axles are mounted; a second frame, on which second axles and a second hydraulic motor driving the second axles are mounted, wherein the first and second frames are connected to each other so as to be relatively rotatable centering on a vertical axis by a steering operation; a hydraulic pump; a hydraulic circuit fluidly connecting the first and second hydraulic motors in series to the hydraulic pump, wherein the hydraulic circuit includes a passage interposed between the first and second hydraulic motors; and pressure control means for releasing oil from the passage between the first and second hydraulic motors when the first and second frames are relatively rotated by the steering operation of the stationary vehicle and backpressure oil discharged from the first and second hydraulic motors is excessively accumulated in the passage between the first and second hydrauli

Abstract: A steering system for a machine having at least one steerable traction device is disclosed. The steering system may have a steering actuator operatively connected to the at least one steerable traction device, and a travel speed sensor configured to generate a signal indicative of a travel speed of the machine. The steering mechanism may also have an operator input device having a deadzone. The deadzone may vary in response to the signal. The steering system may also have a controller in communication with the steering actuator, the operator input device, and the travel speed sensor. The controller may be configured to affect operation of the steering actuator in response to operation of the operator input device only when the operation of the operator input device deviates from the deadzone.

Abstract: A steering system is provided for a work vehicle comprising articulated first and second vehicle sections. The steering system comprises a controller adapted to: determine from a speed-request signal if a requested steering speed requested for the first vehicle section relative to the second vehicle section about an articulation axis toward an end of an end region of a position range of the first vehicle section is at least a predetermined steering speed; determine from a position signal if the first vehicle section is positioned in the end region of the position range; and, if the requested steering speed is at least the predetermined steering speed and the first vehicle section is positioned in the end region, signal that an actual steering speed of the first vehicle section be lower than the requested steering speed. An associated method is disclosed.

Abstract: A vehicle is disclosed having a hydraulic system. The hydraulic system includes a steering input and a feedback to the steering input. In another aspect of the disclosure, an adjustable gain is provided between steering inputs to the system and the steering output from the system.

Abstract: A rear-wheel steering control system for a vehicle/trailer combination that adaptively changes an open-loop feed-forward command signal for different trailers or the same trailer with different configurations based only on vehicle parameters. The system includes a hand-wheel sensor for providing a hand-wheel angle signal of a hand-wheel position of the vehicle, a vehicle speed sensor for providing a vehicle speed signal of the vehicle, and a vehicle yaw rate sensor for providing a measured vehicle yaw rate signal of the vehicle. The system also determines if a vehicle yaw rate has reached a steady state and uses the steady-state yaw rate signal to calculate the rear-wheel steering command. In one embodiment, the system updates feed-forward rear/front values for a plurality of predetermined vehicle speeds when determining the proper rear-wheel steering command.

Abstract: An articulated harvester includes a powered harvester having a pair of forward wheels or tracks, having a pair of rotatable rearward caster wheels, and carrying an on-board harvester grain bin for housing harvested grain. The harvester tows a grain cart, which carries a grain cart bin for housing harvested grain. A joint assembly interconnects the harvester and the grain cart. The joint assembly includes a grain cart tongue that mates with the harvester. An articulation cylinder assembly connects the harvester and the grain cart tongue in the region of the joint assembly. Bi-directional, biased guide rods connect between the grain cart tongue and the caster wheels. The grain car may be steerable and/or powered. The harvester may be steerable by its pair of forward wheels or tracks. A conventional harvester and grain cart assembly can be converted into the novel articulated harvester.

Abstract: An articulated wheel loader provides a cushioned deceleration at the limits of its turning to the left and to the right by reducing fluid flow through a hydraulic steering cylinder as the articulated frames approach abutment. The throttled fluid flow causes a variable displacement pump to de-stroke, which further cushions the deceleration.

Abstract: One embodiment of the present invention relates to systems and methods for controlling handling characteristics of a tire. Another embodiment of the present invention relates to a tire having controllable handling characteristics.

Abstract: A rear part of a vehicle body is supported by a rear-front axle (18) and a rear-rear axle (20), and right and left rear-front wheels (17) rotatably mounted at opposite ends of the rear-front axle (18) are constituted so as to be steered by a steering mechanism. The steering mechanism is driven by an actuator so as to steer the rear-front wheels (17), and the actuator (51) is controlled by the control means. The control means stops the steering of the rear-front wheels (17) when a vehicle speed is approximately zero, and the control means operates the actuator when a difference between a theoretical steering angle of the rear-front wheels (17), relative to that of the front wheels (15), and an actual steering angle exceeds a predetermined value even though the vehicle speed is approximately zero.

Abstract: An all wheel steering system for a vehicle comprising a controller having a first input for receiving a signal from a hand wheel position sensor, a second input for receiving a signal from a vehicle speed sensor, and a third input for receiving a signal that varies depending upon whether a trailer is hitched the vehicle. The controller generates an output for controlling a rear wheel steering actuator. The output varies as a function of the first, second, and third inputs such that when a trailer is hitched to the vehicle the out-of-phase rear steer amount at low speeds is reduced and the in-phase rear steering amount at high speeds is increased.

Abstract: A method for steering a vehicle and a steering system (1) comprises: a vehicle, with a first wheel steering arrangement (10), and a second articulated steering arrangement (11), a steering unit (2) which is common for both steering (10, 11) arrangements and a sensor arrangement connected to a corrective device to sense a steering deflection of the second steering arrangement (11). A dead band is monitored by the steering deflection of the second steering (11) arrangement, a correction of the second steering (11) being effected when leaving the dead band and activating the first steering arrangement (10).

Abstract: A lift truck has a wheeled rear section to which is pivotally connected a wheeled front section, with one of the sections being drivable, in use. The front section, which has lifting forks, is pivoted to an extended length arm at the front of the rear section, to allow the front section to pivot relative the rear section, to at least one side thereof, by an angle substantially greater than 90°. Part of the rear section can be relieved to permit said pivoting.

Abstract: A frame for a work machine includes a first side wall portion having a first and second bore hole defined therein. The frame further includes a second side wall portion having a third and fourth bore hole defined therein. The first bore hole is linearly aligned with the third bore hole, and the second bore hole is linearly aligned with the fourth bore hole. The frame also includes a central wall portion having a fifth and a sixth bore hole defined therein. The central wall portion is positioned such that the fifth bore hole is linearly aligned with the first and third bore holes and the sixth bore hole is linearly aligned with the second and fourth bore holes. The frame has relatively few parts, lower manufacturing costs, and provides greater visibility to an operator of a work machine on which it is mounted.

Abstract: The present invention is addressed to a joint which includes an upper frame member carried by the forward unit and having a recess on its lower side and a lower frame member carried by the forward unit, having a recess on its upper side, and being spaced-apart vertically below the upper frame member so that the recesses are in vertical registration. The joint further includes a shaft carried by the rearward unit and a bearing retainer assembly carried by the end of the shaft and disposed between the recesses. The bearing assembly includes an annulus surmounting a hub connected to the shaft. Thrust bearings between the annulus and hub permit the hub to co-rotate with the shaft with respect to the annulus, while nibs carried by the annulus are associated with tapered roller bearings so that the outer annulus co-twists with the shaft respect to the forward unit.

Abstract: A bolt-together hitch for a machine having articulatable first and second sections, including a generally annular yoke member of cast steel having a cylindrical portion which is trunnion mounted by bearings in a longitudinal bore formed by the first section and a tube member of forged steel bolted end to end to the yoke member, the yoke member integrally forming brackets to provide an articulated pivot joint with the second section.

Abstract: A steering system (1) for a vehicle with a first steering arrangement (6), with a first sensor (7), with a second steering arrangement (8), which includes an articulated steering, which has a second sensor (9), and with a steering unit (5). To improve the steering comfort, the steering unit (5) is fixedly connected with the first steering arrangement (6) and the second steering arrangement (8) is connected with a follow-up arrangement, which comprises the first sensor (7), a control device (10) and a valve arrangement (11).

Abstract: A method for steering a vehicle and a steering system (1) comprises: a vehicle, with a first wheel steering arrangement (10), and a second articulated steering arrangement (11), a steering unit (2) which is common for both steerings (10, 11) arrangements and a sensor arrangement connected to a corrective device to sense a steering deflection of the second steering arrangement (11). A dead band is monitored by means of the steering deflection of the second steering (11) arrangement, a correction of the second steering (11) being effected when leaving the dead band and activating the first steering arrangement (10). The sensor arrangement has a dead band sensor (13; 23, 24) on the second steering (11), which is connected with a correcting device (14), which supplies pressurized fluid to the second steering (11) arrangements on leaving a predetermined dead band and activating the steering unit (2).

Abstract: A steering system (1) for a vehicle with a first steering arrangement (6), with a first sensor (7), with a second steering arrangement (8), which includes an articulated steering, which has a second sensor (9), and with a steering unit (5). To improve the steering comfort, the steering unit (5) is fixedly connected with the first steering arrangement (6) and the second steering arrangement (8) is connected with a follow-up arrangement, which comprises the first sensor (7), a control device (10) and a valve arrangement (11).

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

Abstract: A lift truck (10) having a body (12) with ground engaging means (14) and a steer frame (34) rotatable relative to the body via a steer pivot having a steer axis (A) with the steer axis being fixed relative to the body, the lift truck further including a mast (50) mounted on a steer frame and being rotatably fast therewith when considering the steer axis, the lift truck further including front wheels (66, 68) depending from and steerable by the steering frame, in which the mast is rotatably fast with the front wheels when considering the steer axis, and the mast is mounted substantially above the steer pivot (FIG. 1).

Abstract: In many types of construction machines, the frame assembly comprises a rear frame that supports the engine and drive train components and a front frame that supports the work implement. In this type of machine, the two frames are normally pinned together and the front frame is articulated with respect to the rear frame by a pair of steering cylinders to provide steering for the machine. In the area in which the two frames are pinned together it is necessary to provide structural support, especially in the hitch area of the front frame. The present invention provides a front frame assembly (12) that has an upper and lower hitch plate (118, 120) that are positioned between and secured to the rear portion of a pair of side plates (62, 64) defined by the front frame assembly (12).

Abstract: A log hauler having a wheeled tractor and one or more wheeled log trailers with support wheels which are individually steerable to permit the log hauler to travel in a serpentine manner through a tree harvesting area. The support wheels are vertically adjustable to provide stability as the log hauler traverses uneven ground.

Abstract: The invention relates to a hydraulic steering device for the chassis of a vehicle, in particular of a crane or transport vehicle, with chassis axles steerable between longitudinal and transverse drive positions and in each case fixed to a shaft on the vehicle that is pivoted about a vertical swiveling axle, on which shaft a steering cylinder acts by way of at least one laterally projecting control arm for swiveling of the shaft. The steering cylinder acting on the projecting control arm and a further steering cylinder acting on a vehicle frame beam are articulated to a lever arm, coaxially pivoted on the shaft, in such a way that the torsional movement of the shaft resulting from the retracting and extending movement of the two steering cylinders adds up to at least ±90°.

Abstract: The invention concerns a method of steering a vehicle, particularly an articulated vehicle, in which a valve element of a main valve is moved so that it releases or closes connections between a supply connection arrangement and a working connection arrangement in dependence of a steering direction and a steering angle.

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

Abstract: A steerable machinery trailer (1) has a chassis (2, 33, 35, 36) intermediate a pivotal towing attachment (26, 29, 30, 46) and trailer wheels (3) proximate a rear portion of the chassis. The trailer wheels have pivotal attachment to the trailer and are pivotal for steering with a steering shaft (4) that is length-controllable intermediate rigid positioning on the chassis and a steering arm (6) attached to a steering rod (7) that is connected to a pivotal attachment of the trailer wheels to the chassis. Separately and optionally from being pivotal on the pivotal towing attachment by wheel-following of the trailer wheels, the chassis is pivotal on the pivotal towing attachment with a positioning shaft (8) that is length controllable intermediate rigid positioning on the chassis and a rigid lateral attachment (5, 9) to the towing vehicle. Length changes of the steering shaft steer the trailer wheels to guide the rear portion of the trailer from-side-to-side for selective turn-positioning of the trailer wheels.

Abstract: An articulated train such as a coal haulage system includes first, second, third and fourth vehicles pivotally pinned to one another in end-to-end relationship. In the improvement, the train includes a steering system having first mechanism for selectively securing the second and third vehicles in aligned relationship and second mechanism for selectively securing the third and fourth vehicles in aligned relationship. Turn control mechanism unlocks the first mechanism when the first vehicle turns through a predetermined angle. In an exemplary embodiment, each of the first and second mechanism includes an actuator and a hydraulic valve which coacts with such actuator. The steering system locks those vehicles following the first vehicle in an aligned (i.e.

Abstract: One aspect of the present invention relates to a steering system for an articulated tracked combine composed of (i) a forward unit having a pair of differentially-connected powered non-steering wheels or tracks and (ii) a tracked rearward unit having powered steerable tracks. This steering system includes a pivoting articulation joint interconnecting the forward unit and the rearward unit. The rearward unit is fitted with a differential tracked steering system in steering connection with an operator steering wheel for steering of the articulated tracked combine. Optionally, such novel steering system includes a pair of steering articulation cylinder assemblies connected between the forward unit and the rearward unit. An angle sensor is mounted at the joint for sensing the relative position of the forward unit and the rearward unit. Another sensor is mounted at the steering wheel to sense its position.

Abstract: In many types of construction machines, the frame assembly comprises a rear frame that supports the engine and the majority of the drive train components and a front frame that supports the work implement and related structure. In this type of machine, the two frames are normally pinned together and the front frame is articulated with respect to the rear frame by a pair of steering cylinders to provide steering for the machine. In order to provide the required structural support for the components of the work implement and to accommodate the steering forces, the front frame is necessarily quite large. The present invention provides a front frame (12) structure that includes a pair of main side plates (62, 64) that are positioned a preselected distance (W) from one another and mount a lift arm assembly (30) therebetween to minimize the overall width of the frame assembly. The forward end portion of the front frame assembly (12) has a preselected height (H) that permits the front frame to have a low profile.

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

Abstract: The system for guided steering of a set of rear wheels of a semi-trailer comprises a pulling vehicle and a semi-trailer having rear wheels which are turnable with respect to a chassis of the trailer to turn from a neutral position to one or the other side of the semi-trailer for generating steering of the vehicle in one direction with respect to a neutral position. The system further comprises power generating apparatus to act on the rear wheels to generate turnings of the rear wheels, activating apparatus mounted in the driver's cabin of the vehicle for operation by the driver of the vehicle for generating a steering of the rear wheels independently of the steering of the vehicle as well as locking structure operated from the driver's cabin, in a first position for generating locking of the rear wheels in the neutral position, and switchable from the first position to a second position, where the rear wheels are released and brought to turn by activation of the activating apparatus.

Abstract: A steering system for an articulated steered mobile work machine has a first sensor for sensing the relative angular position of first and second machine sections and a second sensor for sensing the relative angular position of second and a third machine sections. A controller determines for a sensed relative angle of the first and second machine sections the desired relative steering angle of the second and third sections and actuates a second control valve to direct fluid flow to a second pair of fluid operated jacks and pivot the third machine section to a desired angular position relative to the second machine section. The second sensor provides feedback as to the relative angular position of the second and third machine sections.

Abstract: A frame assembly includes a central tower portion having a first side wall portion and a second side wall portion. The first side wall portion has a first leg and a first arm each extending therefrom, and the second side wall portion has a second leg and a second arm each extending therefrom. The frame assembly also includes a hitch support assembly having an upper plate and a lower plate vertically spaced from each other. The hitch support assembly also includes a connecting member interposed between and connected to the upper plate and the lower plate. The hitch support assembly is secured to the central tower portion such that a lower end of both the first leg and the second leg are supported on the lower plate. The frame assembly further includes an axle mount assembly having a first axle plate, a second axle plate, and a support member extending therebetween, wherein both the first arm and the second arm are secured to the support member. A method of manufacturing the frame assembly is also disclosed.

Abstract: A self-propelling agricultural working machine has a machine frame, a not steerable front axle and a rear axle formed as a dismountable pendulum axle connectable to the machine frame in a predetermined connecting point and provided with steerable wheels, an articulated joint releasably hingedly connectable with the machine frame for coupling the working machine with a trailer vehicle, and connecting elements for alternatingly releasably connecting the pendulum axle and the articulated joint with the machine frame in a region of the connecting point.

Abstract: A steering system for an articulated steered mobile work machine has a first sensor for sensing the relative angular position of first and second machine sections and a second sensor for sensing the relative angular position of second and a third machine sections. A controller determines for a sensed relative angle of the first and second machine sections the desired relative steering angle of the second and third sections and actuates a second control valve to direct fluid flow to a second pair of fluid operated jacks and pivot the third machine section to a desired angular position relative to the second machine section. The second sensor provides feedback as to the relative angular position of the second and third machine sections.

Abstract: In many types of construction machines, the frame assembly comprises a rear frame that supports the engine and the majority of the drive train components and a front frame that supports the work implement and related structure. In this type of machine, the two frames are normally pinned together and the front frame is articulated with respect to the rear frame by a pair of steering cylinders to provide steering for the machine. In order to provide the required structural support for the components of the work implement and to accommodate the steering forces, the front frame is necessarily quite large. The present invention provides a front frame (12) structure that includes a pair of main side plates (62, 64) and a substantially planar support plate (74) that is mounted to a first end portion of the side plates (62, 64). The support plate (74) mounts an axle assembly directly thereto and defines a pair of mounting bores (84) that are positioned, on a rearmost portion of the support plate (74).

Abstract: An articulated vehicle comprising a first vehicle portion attached to a second vehicle portion by a joint assembly. The joint assembly preferably comprises a bearing assembly that is pivotally attached to the first vehicle portion such that the bearing assembly can pivot relative to the first vehicle portion about a substantially horizontal axis that is substantially transverse to the longitudinal axis of the vehicle. The bearing assembly is also preferably pivotally attached to the second vehicle portion such that the bearing assembly can pivot relative to the second vehicle portion about a substantially vertical axis. The bearing assembly is preferably constructed to enable the first vehicle portion to rotate about the longitudinal axis relative to the second vehicle portion.

Abstract: A multipurpose construction vehicle bears on its vehicle frame, which is realized as an axle-link pivot or center pivot type, a front swing loading device and a rear-mounted excavator. The swing loading device is permanently connected above the front axle (3) to a front subframe (22) which forms part of the vehicle frame, and the rear-mounted excavator is permanently connected to a rear subframe (32) which is connected to the rear axle (5) and forms part of the vehicle frame, both subframes (22, 32) being connected to one another at a suitable point along the longitudinal center axis of the vehicle by means of a self-aligning bearing (34) which can swivel about this longitudinal axis to a limited degree and by means of cylinders arranged at a distance from the self-aligning bearing on both sides, so that the two subframes can be locked with respect to one another at any desired swivel position.

Abstract: A steering system for an articulated vehicle (11) including steering cylinders (19, 21) wherein the steering system includes a steering control valve (31) having a housing (33) fixed to a rear bogie portion (15). The steering control valve (31) includes a spool valve (49) receiving steering input and a follow up sleeve valve (51) which receives feedback representative of a change in the articulation angle of the front bogie portion (13) by means of a linkage arrangement (123, 117, 63). Either the follow up movement of the sleeve relative to the spool, to reduce main system flow, or the follow up of the sleeve relative to the housing, to reduce the load signal, is used as a way of cushioning the steering, as the front and rear bogie portions (13, 15) approach maximum articulation.

Abstract: A work vehicle includes an articulation joint between a front section and a rear section. The articulation joint comprises two vertically spaced pivotal support bearings defining a rotational axis of the joint. First and second drive trains extend through the joint for transmitting drive power between the front and rear sections of the vehicle. Steering actuators which are coupled between the front and rear sections for selectively articulating the joint are trunnion-mounted, providing a compact articulation joint. Free volumes are provided adjacent to cap ends of the actuators to allow for pivotal movement of the steering actuators during articulation of the joint. The first drive train extends between an engine in one section of the vehicle and a transmission in the other section for driving the transmission and a first set of wheels, while the second drive train extends from the transmission to the first section of the vehicle for driving a second set of wheels.

Abstract: An articulated vehicle made of a front and of a rear vehicle body of which the chassis are connected by an articulated joint. The articulated joint comprises a steering axis, a first longitudinal roll axis on the front chassis, and a second longitudinal roll axis on the rear chassis. In a structural sense, the articulated joint of the present invention comprises a first swivel member and a first shaft mounting this first swivel member on the front chassis for relative oscillation of the first swivel member and of the front chassis about the first longitudinal roll axis. Likewise, a second swivel member and a second shaft mounting this second swivel member on the rear chassis allow relative oscillation of the second swivel member and of the rear chassis about the second longitudinal roll axis.

Abstract: In many instances it has been a recent trend to incorporate the use of electronic controls into various machine functions to reduce the fatigue of an operator. When incorporated into the steering functions of a machine, the electronic controls often do not provide an operator with an "automotive" feel and thus do not work as well in some machine applications as they do in others. The present invention incorporates a mechanical feedback through the steering controls to provide the operator with a feel similar to that of an automotive environment. In addition, the steering controls operate in a manner which provides a variable ratio of steering wheel rotation to steering control valve actuation depending upon the articulation angle of the machine. In so doing, the function of the steering controls will vary with and enhance the operation of each specific mode of machine operation.

Abstract: A rear frame for center pivot steered construction machinery which, for receiving adjacent machine parts or subassemblies, is formed of components extending in the longitudinal direction of the frame and constitute bearing components which can be connected with each other by further transversely extending components. When assembled, the result is a basic structure in the shape of a box which is closed or can be closed by machine parts or adjoining subassemblies.

Abstract: An articulated tracked vehicle for agricultural harvesting which reduces damage to fields and can be driven on paved roads at reasonable speeds. The vehicle has front and rear elements, linked by an articulating joint which permits turning and rotation of one element with respect to the other. Each element is motivated by a pair of tracked power units which are hydraulically driven by a heavy duty differential between the units. Each power unit is rotatably mounted solely on a shaft sleeve of the differential and is free to oscillate vertically and independently to absorb irregularities in its path. Each unit includes an endless elastomeric track which has two rows of lugs on its inner surface. A novel drive mechanism engages these lugs to motivate the vehicle. A sealed transmission housing in each power unit protects key drive elements from environmental damage without interfering with operation of the unit.

Abstract: An electrohydraulic steering system has a three position pilot operated directional valve disposed between a variable displacement pump and a pair of steer cylinders. The directional valve controls the direction of fluid flow from the pump to the steer cylinders while the displacement of the variable displacement pump is controlled to vary the rate of fluid flow to the steer cylinders. The directional valve is moved to an on position in response to a pilot signal delivered thereto from a pilot valve device while the displacement setting of the variable displacement pump is varied by an electrical signal delivered to a displacement controller from a position sensor mechanism.

Abstract: The present invention provides an electro-hydraulic steering system for an articulated vehicle having a front frame and a rear frame. The system includes a controller and a hydraulic steering system having a pump for providing hydraulic pressure. A steering input control, typically a steering wheel, transmits mechanical steering inputs to the hydraulic steering system. A pair of articulation cylinders rotate the front frame with respect to the rear frame in response to hydraulic pressure to steer the vehicle. Position sensors transmit input signals to the controller indicating the position of the steering input control and each of the articulation cylinders. An electro-hydraulic valve receives electrical control signals from the controller to control the hydraulic pressure to each articulation cylinder. In this manner, the present invention can perform steering performance enhancements, such as snubbing, steering jerk limit control, and electronic steering adjustment.