Patent Description:
Some agricultural vehicles are configured to be operated in fields among row crops. Application machines such as self-propelled sprayers, for example, may have wheels configured to pass between crop rows and a spray boom that extends outwardly from the vehicle to spray the crop as the machine travels through the field. To avoid damaging the crops as the vehicle moves through the field, each of the wheels must have the proper width to travel between the rows, and the track width-the lateral distance between the wheels-must match row spacing so that the wheels are properly positioned between crop rows. Furthermore, the vehicle should have sufficient ground clearance (the distance between the vehicle body and the surface over which it moves) to clear the crops.

While a standard-height agricultural vehicle may be used to process short crops, such as early stage corn or the like, difficulties arise when processing taller crops, such as mature corn, that are taller than the ground clearance of a standard vehicle. For such crops, high-clearance vehicles may be used. While high-clearance vehicles provide sufficient clearance to pass over the top of taller crops, they suffer from various limitations. For example, high-clearance vehicles, such as those that provide a crop clearance of seventy inches (<NUM>) or more, may have an overall height that exceeds highway height restrictions, thereby making the transport of such vehicles to and from the field difficult. For example, public highways often restrict the height of a load to twelve feet (<NUM>) or less, which may be exceeded when a high-clearance vehicle is placed on a transport trailer. Thus, measures may need to be taken to lower the vehicle to an acceptable transport height, such as deflating the tires or entirely removing the wheels.

In addition, while high-clearance vehicles may be desirable for use on tall crops, they are not as effective in processing shorter crops without added complexity in the boom lifting mechanism to accommodate the range of motion required to place the boom at the proper height above the crop when spraying at the various crop heights.

<CIT>, discloses a self-propelled sprayer having a chassis-height adjustment system wherein each of four wheel support assemblies are configured to selectively raise and lower the chassis relative to the ground surface by actuators. Furthermore, the sprayer includes a track-width adjustment system including telescopic axles and actuators for moving inner axles between extended and retracted positions. Control of the chassis adjustment system and track-width adjustment system may be integrated to preserve the track width during adjustment of the height. However, variations in operating characteristics of the various actuators and control valves can lead to uneven or interrupted adjustment of the height and/or track width, in turn making for an uncomfortable operator experience.

The above section provides background information related to the present disclosure which is not necessarily prior art.

<CIT> discloses a self-propelled sprayer with systems for adjusting chassis height and track width. The chassis-height adjustment system includes a height adjustment actuator for each wheel. The height adjustment actuators can be controlled independently to enable the chassis to be maintained in a horizontal position when the vehicle is operating on a slope. The track-width adjustment system can be actuated remotely from a driver cab so that the track width can be adjusted when the vehicle is moving without the driver leaving the cab.

A method is disclosed for controlling a chassis-height adjustment system to selectively raise and lower a chassis relative to a ground surface. The system comprises a chassis, a plurality of ground-engaging elements supporting the chassis above a ground surface, and a plurality of support assemblies supporting the chassis on the ground-engaging elements. The support assemblies each comprise a height adjustment actuator. A plurality of height position sensors are each disposed to sense an adjustment position of a respective one of the height adjustment actuators and to generate a height signal that is representative of that adjustment position. The method includes receiving a chassis-height adjustment command and monitoring the height signal for each of the plurality of height adjustment actuators. A first height signal corresponding to a first height adjustment actuator is compared to height signals corresponding to the other height adjustment actuators, and the first height adjustment actuator is only adjusted if the first height signal is within a height tolerance range with respect to the height signals that correspond to the other height adjustment actuators. Advantageously, by stopping movement of one or more of the height adjustment actuators when their position falls outside of a tolerance range with respect to the other height adjustment actuators, the uniformity of chassis-height adjustments may be improved.

Another embodiment includes a chassis-height adjustment system for selectively raising and lowering a chassis relative to a ground surface. The system comprises a chassis, a plurality of ground-engaging elements supporting the chassis above a ground surface, and a plurality of support assemblies supporting the chassis on the ground-engaging elements and comprising a height adjustment actuator. A plurality of height position sensors are each disposed to sense an adjustment position of a respective one of the height adjustment actuators and to generate a height signal that is representative of that adjustment position. A controller is configured to receive a chassis-height adjustment command and to monitor the height signal for each of the plurality of height adjustment actuators. A first height signal corresponding to a first height adjustment actuator is compared to height signals corresponding to the other height adjustment actuators. The first height adjustment actuator is automatically adjusted only if the first height signal is within a height tolerance range with respect to the height signals that correspond to the other height adjustment actuators.

In another embodiment, a method is used to control a chassis-height adjustment system for selectively raising and lowering a chassis relative to a ground surface. The system comprises a chassis, a plurality of ground-engaging elements supporting the chassis above a ground surface, and a plurality of support assemblies supporting the chassis on the ground-engaging elements. Each support assembly comprises a height-adjustment actuator. Each of the support assemblies are mounted to the chassis by a respective track-width adjustment mechanism having a track-width adjustment actuator configured to shift the position of the associated ground-engaging element laterally relative to the chassis. A plurality of height position sensors are each disposed to sense an adjustment position of a respective one of the height adjustment actuators and generate a height signal representative of that adjustment position. A plurality of track-width position sensors are each disposed to sense an adjustment position of a respective one of the track-width adjustment actuators and generate a track-width signal representative of that adjustment position. The method comprises receiving a chassis-height adjustment command and monitoring the height signal for each of the plurality of height adjustment actuators and the track-width signals for each of the track-width adjustment actuators. The first height adjustment actuator is adjusted only if the first height signal is within a track-width tolerance range with respect to the track-width signals.

In some embodiments, a vehicle comprises a chassis, a plurality of ground-engaging elements supporting the chassis above a ground surface, and a motor for driving at least one of the ground-engaging elements to propel the machine along the ground surface. A chassis-height adjustment system is configured for selectively raising and lowering the chassis relative to the ground surface and comprises a plurality of height adjustment actuators, each corresponding to one of the ground-engaging elements. A track-width adjustment system is configured for shifting the position of at least one of the ground-engaging elements laterally relative to the chassis and comprises a plurality of track-width adjustment actuators, each corresponding to one of the ground-engaging elements. A controller is configured to automatically actuate the track-width adjustment system when the chassis-height adjustment system is actuated to preserve a constant track width as the chassis moves up or down relative to the ground surface, and to stop movement of one or more of the height adjustment actuators in response to a sensed position of the height adjustment actuators being outside of a height tolerance with respect to sensed positions of the other height adjustment actuators or being outside of a track-width tolerance with respect to sensed positions of the track-width adjustment actuators.

The independent suspension assemblies of a mobile machine with an adjustable height chassis may be controlled so that the assemblies extend and retract in a synchronized manner when the chassis is raised and lowered. In some embodiments in which a track width is adjusted simultaneously with the chassis height, the track width and height adjustments are controlled so as to be synchronized. If the machine is on level ground, the suspension assemblies may be controlled such that the machine remains level while the chassis is raised and lowered.

In some embodiments, sensors provide data to a control system indicating the extent to which each of the suspension assemblies is extended or retracted and also, in some embodiments, the lateral position of each wheel. In some embodiments, the control system uses that data when raising and lowering the chassis to determine whether to adjust operation of one or more components to improve synchronization.

This summary is provided to introduce a selection of concepts in a simplified form that are further described in the detailed description below. Other aspects and advantages of the present disclosure will be apparent from the following detailed description and the accompanying drawing figures.

While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the present disclosure, various features and advantages may be more readily ascertained from the following description of example embodiments when read in conjunction with the accompanying drawings, in which:.

The illustrations presented herein are not actual views of any crop sprayer or portion thereof, but are merely idealized representations to describe example embodiments of the present disclosure. Additionally, elements common between figures may retain the same numerical designation.

The following description provides specific details of embodiments. The drawings accompanying the application are for illustrative purposes only, and are thus not drawn to scale.

In this description, references to "one embodiment," "an embodiment," or "embodiments" mean that the feature or features being referred to are included in at least one embodiment of the technology. Separate references to "one embodiment," "an embodiment," or "embodiments" in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be readily apparent to those skilled in the art from the description. For example, a feature, structure, act, et cetera, described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, the present technology can include a variety of combinations and/or integrations of the embodiments described herein.

Turning now to the drawing figures, and initially <FIG>, an exemplary applicator <NUM> includes a chassis <NUM>, a plurality of wheels <NUM> or other ground-engaging elements supporting the chassis <NUM> above a ground surface, an application system <NUM>, an operator cabin <NUM>, and an engine compartment <NUM>. A plurality of support assemblies <NUM> interposed between the wheels <NUM> and the chassis <NUM> support the chassis <NUM> on the wheels <NUM> and provide suspension, height adjustment, and/or steering functions, as discussed in greater detail below.

Certain components of the applicator <NUM> have been omitted from the figures for simplicity of illustration and to show certain features of the applicator <NUM> that would otherwise be concealed. The engine, for example, has been omitted to illustrate components of the applicator frame, including portions of the front axle <NUM>. Certain hydraulic lines, such as hydraulic lines running to and from the assemblies <NUM>, are also omitted. The applicator <NUM> is illustrated and discussed herein as an exemplary machine with which the support assemblies <NUM> may be used. It will be appreciated by those skilled in the art that the support assemblies <NUM> may be used with other machines including other types of applicators or other vehicles or mobile machines that would benefit from the advantages of the various embodiments of the support assemblies disclosed herein, such as chassis height adjustment and independent suspension.

The applicator <NUM> includes a pair of front wheels 14b, 14c and a pair of rear wheels 14a, 14d (rear wheel 14d hidden from view) of the appropriate size and shape to allow the applicator <NUM> to travel among row crops with minimal crop disturbance. A used herein, a "wheel" includes an inner, rigid wheel and an outer, flexible tire mounted on the wheel unless otherwise specified. Each wheel <NUM> may exhibit, for example, an outer diameter of between <NUM> inches (<NUM>) and <NUM> inches (<NUM>) and a width of between <NUM> inches (<NUM>) and <NUM> inches (<NUM>). More specifically, wheels <NUM> designed for use with row crops may exhibit an outer diameter of about <NUM> inches (<NUM>) or about <NUM> inches (<NUM>) and a width of about <NUM> inches (<NUM>). Alternatively, the wheels <NUM> may exhibit a width of up to <NUM> inches (<NUM>) (or more) for pre-emergent applications, for use on soft terrain, or both to maximize flotation and minimize soil compaction. Each of the wheels <NUM> may weigh between <NUM> pounds (<NUM>) and <NUM>,<NUM> pounds (<NUM>) and may specifically weigh about <NUM> pounds (<NUM>) or about <NUM> pounds (<NUM>). In one exemplary embodiment, each of the wheels <NUM> is about <NUM> inches (<NUM>) tall, about <NUM> inches (<NUM>) wide, and weighs about <NUM> pounds (<NUM>).

The particular size, shape, and configuration of the wheels <NUM> may vary substantially from one embodiment to another. In some embodiments, the vehicle may include ground-engaging elements other than wheels, such as tracks. Hereinafter, reference will be made to a "wheel" or "wheels" with the understanding that the illustrated wheels <NUM> may be replaced with other types of ground-engaging elements.

One or more drive motors <NUM> may be associated with one or more of the wheels <NUM> for driving rotation of the wheel or wheels relative to the chassis <NUM> to propel the applicator <NUM> in forward and reverse directions. In the illustrated embodiment, a separate hydraulic motor <NUM> is drivingly connected to each wheel <NUM> such that each of the wheels <NUM> may be driven independently to propel the applicator <NUM>. Either two or all four of the wheels <NUM> may be steerable. In some embodiments, the steering functionality of some of the wheels <NUM> may be selectively enabled and disabled. By way of example, the front wheels 14b, 14c may always be steerable while supplemental steering provided by the rear wheels 14a, 14d may be selectively enabled and disabled. An operator may control the drive motors <NUM> and steering functions of the wheels <NUM>, including enabling and disabling the steering ability of certain of the wheels <NUM>, from one or more of the user interface elements of the cabin illustrated in <FIG>.

The applicator <NUM> includes mechanisms for adjusting the track width of the wheels <NUM> to accommodate, for example, different spacing needs for row crops. In the illustrated embodiment, the applicator <NUM> includes telescoping axles with an outer axle <NUM> and an inner axle <NUM> associated with each wheel <NUM>, wherein the inner axle <NUM> slidingly engages the outer axle <NUM> and allows the wheel <NUM> to shift laterally relative to the chassis <NUM>. A hydraulic piston or similar actuator may drive the inner axle <NUM> inward and outward to shift the position of the wheel <NUM>. The inner <NUM> and outer <NUM> axles form part of the chassis <NUM> and, in the illustrated embodiment, the outer axles <NUM> are rigidly connected to another portion of the chassis, such as one or more frame elements. <CIT>, discloses an example of a telescopic axle with an actuator disposed inside the outer axle and arranged to drive the inner axle inward and outward to shift the lateral position of the associated support assembly and wheel.

The application system <NUM> is supported on the chassis <NUM> and may be conventional in nature. In the illustrated embodiment, the application system <NUM> includes a liquid holding tank <NUM> and a delivery system <NUM> for applying a liquid from the holding tank <NUM> to a crop or field. The holding tank <NUM> may have a capacity of between <NUM> gallons (<NUM> I) and <NUM>,<NUM> gallons (<NUM>,<NUM> I) and, more specifically, may have a capacity of <NUM> gallons (<NUM>,<NUM> I), <NUM> gallons (<NUM>,<NUM> I), <NUM>,<NUM> gallons (<NUM>,<NUM> I), or <NUM>,<NUM> gallons (<NUM>,<NUM> I). The delivery system <NUM> includes a pair of booms <NUM> supporting hoses, pumps, and spray nozzles or similar components for dispersing or otherwise applying the contents of the tank <NUM> to a crop. Alternatively, the application system <NUM> may be configured to apply dry material to a field and therefore may include a hopper and a mechanism for dispersing particulate material from the hopper, such as a pneumatic spreader or one or more spinners.

The operator cabin <NUM> or "cab" is supported on the chassis <NUM> and positioned forward of the application system <NUM>. The cabin <NUM> presents a control environment <NUM> (<FIG>) including a steering wheel <NUM>, one or more pedals <NUM>, a drive lever <NUM>, one or more electronic instrument panels <NUM>, and a control panel <NUM> including buttons, switches, levers, gauges, and/or other user interface elements. The various components of the control environment <NUM> enable the operator to control the functions of the applicator <NUM>, including driving and operating the application system <NUM>. The various user interface elements are positioned around and proximate a seat <NUM> for easy access by an operator during operation of the applicator <NUM>. The control environment <NUM> may include a touchscreen display. One or both of the electronic instrument panels <NUM>, for example, may be or include a touchscreen, or a display terminal with a touchscreen may be mounted on or near the control panel <NUM>.

As mentioned above, the applicator <NUM> includes a support assembly <NUM> interposed between each of the wheels <NUM> and the chassis <NUM>. Each support assembly <NUM> connects to a hub of one of the wheels <NUM> and to one of the inner axles <NUM> such that the wheel <NUM> and the support assembly <NUM> shift laterally as a single unit relative to the chassis <NUM> when the inner axle <NUM> is shifted relative to the outer axle <NUM> to adjust the applicator's track width. In some embodiments, the support assemblies <NUM> include height adjustment components for raising and lowering the chassis <NUM> of the vehicle between various operating positions. One or more of the support assemblies <NUM> (or portions thereof) may be selectively pivotable relative to the chassis <NUM> to steer the applicator <NUM>.

Each of the support assemblies <NUM> includes one or more actuators for adjusting a height of the chassis, for steering the associated wheel, or both. In some embodiments, the actuators are hydraulic actuators such as linear or rotary hydraulic actuators. <FIG> illustrates an exemplary hydraulic control system <NUM> for operating hydraulic actuator sections <NUM> in which a centralized hydraulic pump <NUM>, driven by an internal combustion engine <NUM> or other power source, communicates pressurized hydraulic fluid to a hydraulic controller <NUM> that regulates fluid flow between the pump <NUM> and the hydraulic actuator sections <NUM> associated with the support assemblies via a plurality of hydraulic transfer lines <NUM>. The hydraulic controller <NUM> may include, for example, a hydraulic manifold or similar device.

Each of the hydraulic transfer lines <NUM> communicates hydraulic power between the hydraulic controller <NUM> and one or more hydraulic actuator sections <NUM> and, thus, may include one or more hydraulic pressure lines and one or more hydraulic return lines. Each of the hydraulic transfer lines may communicate hydraulic power to more than one actuator, and each of the actuator sections <NUM> may include a group of actuators associated with each wheel <NUM> and/or assembly <NUM>. By way of example, a first actuator associated with the actuator section <NUM> may drive steering of the wheel, a second actuator may drive rotation of the wheel, and a third actuator may adjust a height of the chassis <NUM>. It will be appreciated that the actuator sections <NUM> are exemplary in nature and that the various hydraulic actuators may not be grouped as described herein.

The system <NUM> includes a control interface <NUM> in communication with the hydraulic controller <NUM>. The control interface <NUM> may be part of a user interface that includes one or more physical or virtual user interface elements <NUM>, such as buttons, switches or dials, and may be part of the control environment <NUM> illustrated in <FIG>.

It will be appreciated that various different types of technology may be used to actuate the support assemblies <NUM>. Thus, while the various actuators are illustrated and described herein as hydraulic actuators, it will be understood that other types of actuators may be used in place of, or in connection with, the hydraulic actuators. By way of example, electro-mechanical actuators may be used in place of at least some of the hydraulic actuators illustrated and discussed herein.

<FIG> illustrates another exemplary control system <NUM> similar to the system <NUM> but that includes a computerized controller <NUM> with a control module <NUM> for controlling the hydraulic controller <NUM>. The system <NUM> may also include a wireless interface element <NUM> in wireless communication with the controller <NUM> for allowing a user to remotely control the actuator sections <NUM>. The wireless interface element <NUM> may be a dedicated device, such as a device similar to a key fob commonly used with cars and other vehicles, or a computing device such as smart phone, tablet computer, or wearable computing device programmed or configured for use with the system <NUM>. The wireless interface element <NUM> may be configured to communicate with the hydraulic controller <NUM> and/or the computerized controller <NUM> via short-range wireless communications, such as Wi-Fi or Bluetooth, or via a communications network such as a cellular network.

The controller <NUM> may include one or more integrated circuits programmed or configured to control the hydraulic controller <NUM> to actuate the support assemblies <NUM>. By way of example, the controller <NUM> may include one or more general purpose microprocessors or microcontrollers, programmable logic devices, or application specific integrated circuits. The controller <NUM> may also include one or more discrete and/or analog circuit components operating in conjunction with the one or more integrated circuits, and may include or have access to one or more memory or storage elements operable to store executable instructions, data, or both. The control module <NUM> may be a hardware or software module specifically dedicated to enabling the controller <NUM> to control the hydraulic controller <NUM> as described herein.

Another control system <NUM> illustrated in <FIG> is similar to the system <NUM> but includes additional hydraulic circuit components, such as hydraulic accumulators <NUM>. In some embodiments, each of the support assemblies <NUM> may include a single hydraulic actuator that both raises and lowers the chassis <NUM> and provides suspension functions, as explained below. Such hydraulic systems may require specialized hydraulic circuit components such as the hydraulic accumulators <NUM>.

<FIG> illustrates an embodiment of a hydraulic control system <NUM> for controlling height adjustment cylinders 93a-d and track-width adjustment cylinders 132a-d. The height adjustment cylinders 93a-d are each associated with one of the support assemblies 22a-d, and are fluidly connected to a pressurized line 'P' and a drain line 'D' via respective <NUM>-way <NUM>-position directional height adjustment valves 125a-d. The height adjustment valves 125a-d are shown grouped together as a height adjustment control module <NUM>, which is in electrical or wireless communication with hydraulic controller <NUM>. Each height adjustment cylinder <NUM> is configured to extend to increase the height of the chassis <NUM> and to retract to decrease the height of the chassis <NUM>. Although <FIG> illustrates only a single height adjustment cylinder <NUM> for each support assembly <NUM>, two or more cylinders may instead be employed. For example, the embodiment of <FIG> includes two height adjustment cylinders <NUM>, <NUM>. Some components of the hydraulic circuit are omitted from <FIG> for sake of clarity. For example, each cylinder may have associated therewith a pressure-relief or non-return valve as is standard practice.

Referring once again to <FIG>, a respective height position sensor <NUM> is mounted to, or associated with, each of the height adjustment cylinders <NUM> and configured to sense the extension of the associated height adjustment cylinder <NUM> and, in response, generate a signal representative of the extension of the height adjustment cylinder <NUM>, this 'height signal' being communicated to the controller <NUM>. In an alternative embodiment, the height position sensors <NUM> may instead be disposed remote from the height adjustment actuators <NUM> and instead sense the relative position between two components of the associated support assembly to generate a signal representative of the extension of the height adjustment cylinder <NUM>. The controller <NUM> is thus arranged to receive, as a control input, a height signal for each support assembly <NUM>.

The track-width adjustment cylinders 132a-d are each connected between one of the outer axles 28a-d and one of the inner axles 30a-d, and are fluidly connected to the pressurized line 'P' and drain line 'D' via respective <NUM>-way <NUM>-position directional track-width adjustment valves 135a-d. The directional track-width adjustment valves 125a, 125b associated with the right-hand wheels 14a, 14b are shown grouped together as a right-hand track-width adjustment control module 136R. The directional track-width adjustment valves 125c, 125d associated with the left-hand wheels 14c, 14d are shown grouped together as a left-hand track-width adjustment control module <NUM>. Both the track-width adjustment modules 136R, <NUM> are in electrical or wireless communication with hydraulic controller <NUM>.

A respective track-width position sensor <NUM> is mounted to, or associated with, each of the height adjustment cylinders <NUM> and configured to sense the extension of the associated cylinder and, in response, generate a signal that is representative of the extension of the track-width adjustment cylinder <NUM>, this 'track-width signal' being communicated to the controller <NUM>. In an alternative embodiment, the track-width position sensors <NUM> may instead be disposed remote from the track-width adjustment cylinders <NUM> and instead sense the relative position between the inner and outer axles <NUM>, <NUM> of the associated wheel <NUM> to generate a signal representative of the extension of that height adjustment cylinder <NUM>. The controller <NUM> is thus arranged to receive, as a control input, a track-width signal for each wheel <NUM>.

One of the support assemblies <NUM> is illustrated in greater detail in <FIG>. It should be understood that the assembly <NUM> is one example and many alternative constructions may be adopted instead. <CIT>, referenced above, discloses a number of different support assembly configurations that may be adapted for implementing aspects disclosed herein.

The assembly <NUM> broadly includes a chassis attachment component <NUM> for attaching to the vehicle chassis <NUM>; a wheel attachment component <NUM> for attaching to a wheel <NUM> or other ground-engaging element; a suspension component <NUM> operably interposed between the chassis attachment component <NUM> and the wheel attachment component <NUM> for regulating motion transfer between the two attachment components <NUM>, <NUM>; a plurality of strut bars <NUM>, <NUM> connecting the wheel attachment component <NUM> to the suspension component <NUM>, and a height adjustment mechanism <NUM> comprising a plurality of height adjustment actuators <NUM>, <NUM> for shifting the wheel attachment component <NUM> between a plurality of operating positions relative to the chassis attachment component <NUM>. The chassis attachment component <NUM> may include a pivot element <NUM> for allowing the assembly <NUM> to pivot relative to the chassis <NUM> and a pivot actuator may drive the pivoting motion to thereby steer a wheel or other ground-engaging element connected to the wheel attachment component <NUM>. In the illustrated embodiment, the pivot element <NUM> is or includes a rotary actuator.

The wheel attachment component <NUM> has a generally cylindrical body <NUM> and a pair of upwardly-opening receptacles <NUM> for receiving and connecting to the strut bars <NUM>, <NUM>. The receptacles <NUM> are positioned on opposite sides of and above the cylindrical body <NUM>. Pivot torque is transferred to the wheel attachment component <NUM> by the strut bars <NUM>, <NUM> via the receptacles <NUM>. The wheel attachment component <NUM> includes a plurality of apertures or other features spaced angularly around the body <NUM> for connecting to a hub of a wheel, a hydraulic motor and/or a gear reduction hub, a caliper disc brake assembly, a parking brake assembly, and/or similar components.

The suspension component <NUM> includes a lower suspension member <NUM>, an upper suspension member <NUM>, and a pneumatic spring <NUM> or similar motion-regulating element positioned between and attached to the upper and lower suspension members. The upper suspension member <NUM> is connected to a top side or portion of the spring <NUM> and the lower suspension member <NUM> is connected to a lower side or portion of the spring <NUM>. Each of the upper <NUM> and lower <NUM> suspension members has an elongated shape and includes a plurality of apertures or other features for attaching to the spring <NUM>. The lower suspension member <NUM> includes apertures or other features located proximate end portions thereof to facilitate connection to the strut bars <NUM>, <NUM>, and the upper suspension member <NUM> includes apertures or other features located proximate outer portions thereof to facilitate connection to the adjustment mechanism <NUM>. In the illustrated embodiment, the upper suspension member <NUM> is longer than the lower suspension member <NUM>, enabling attachment to the height adjustment actuators <NUM>, <NUM> that are positioned outboard of the lower suspension member <NUM>.

The pneumatic spring <NUM> uses trapped or compressed air or other fluid to regulate motion transfer between the chassis attachment component <NUM> and the wheel attachment component <NUM>. The pneumatic spring <NUM> may contain air, water, nitrogen, antifreeze or other fluid and may be single, double, or triple convolute. A pair of flexible straps <NUM> may be positioned on opposite sides of the spring <NUM> to limit extension of the spring and a bumper may be positioned inside or outside the spring to limit spring compression. Other technologies may be used, including, for example, a coil-type compression spring and a shock-absorbing cylinder and piston assembly.

The suspension components <NUM> of the assemblies <NUM> may be the only components of the applicator <NUM> configured to regulate motion transfer between the wheels <NUM> (or other ground-engaging element) and the chassis <NUM>. The outer axles <NUM>, for example, may be rigidly connected to portions of the frame of the applicator <NUM>. Furthermore, the suspension components <NUM> regulate motion transfer between the wheels <NUM> and the chassis <NUM> regardless of the operating position of the assemblies <NUM>. Thus, the suspension components <NUM> perform essentially the same function regardless of whether the chassis <NUM> is in a lowered position (e.g., <FIG>), a raised position (e.g., <FIG>) or somewhere in between.

The first strut bar <NUM> and the second strut bar <NUM> are rigidly connected to the receptacles <NUM> of the wheel attachment component <NUM> and are rigidly coupled with the suspension component <NUM> such that movement of the wheel attachment component <NUM> relative to the chassis attachment component <NUM> is communicated through the suspension component <NUM> via the strut bars <NUM>, <NUM>. More specifically, a first end of the first strut bar <NUM> is connected to a first receptacle <NUM> of the wheel attachment component <NUM>, and a first end of the second strut bar <NUM> is connected to a second receptacle <NUM> of the wheel attachment component <NUM>. A second end of the first strut bar <NUM> is connected to a first side of the lower suspension member <NUM>, and a second end of the second strut bar <NUM> is connected to a second side of the lower suspension member <NUM>. As explained above, the lower suspension member <NUM> is an elongated, rigid member with outer apertures on opposing ends thereof for connecting to the strut bars <NUM>, <NUM> and one or more inner apertures between the outer apertures for rigidly attaching to a first side or portion of the spring <NUM>. Thus, the lower suspension member <NUM> interconnects the spring <NUM> and the strut bars <NUM>, <NUM>.

The first and second strut bars <NUM>, <NUM> are parallel or substantially parallel and are separated by a space. The strut bars <NUM>, <NUM> slidingly engage the chassis attachment component <NUM> to allow the wheel attachment component <NUM> to move relative to the chassis attachment component <NUM> while also transferring pivot torque between the wheel attachment component <NUM> and the chassis attachment component <NUM>. The strut bars <NUM>, <NUM> may be separated by a space of between about <NUM> inches (<NUM>) and <NUM> inches (<NUM>) and, more specifically, may be separated by a space of between about <NUM> inches (<NUM>) and about <NUM> inches (<NUM>). The length of each of the strut bars <NUM>, <NUM> may be between about <NUM> inches (<NUM>) and about <NUM> inches (<NUM>) and, more specifically, between about <NUM> inches (<NUM>) and about <NUM> inches (<NUM>). The strut bars <NUM>, <NUM> may be positioned symmetrically about a center of the wheel attachment component <NUM> and a center of the chassis attachment component <NUM>.

The chassis attachment component <NUM> comprises a lower chassis attachment member <NUM> and an upper chassis attachment member <NUM> separated by a space. The pivot element <NUM> is interposed between, and rigidly connected to, the attachment members <NUM>, <NUM>. Each of the lower <NUM> and upper <NUM> chassis attachment members includes a pair of spaced through-holes in axial alignment for slidingly receiving the strut bars <NUM>, <NUM>. Each of the lower <NUM> and upper <NUM> chassis attachment members also includes a pair of apertures or other features positioned outboard of the through-holes for engaging the height adjustment actuators <NUM>, <NUM>.

The chassis attachment component <NUM> is rigidly but adjustably coupled with the upper suspension member <NUM> via the height adjustment actuators <NUM>, <NUM> such that actuating the adjustment mechanism <NUM> causes the upper suspension member <NUM> to shift relative to the chassis attachment component <NUM>, shifting the wheel attachment component <NUM> relative to the axle <NUM>. The lower suspension member <NUM> is rigidly connected to the wheel attachment component <NUM> via the strut bars <NUM>, <NUM>, as explained above, such that motion transfer between the chassis attachment component <NUM> and the wheel attachment component <NUM> passes through, and is regulated by, the suspension component <NUM>. Such motion transfer may correspond to up-and-down movement of the wheels <NUM> relative to the chassis <NUM> such that the suspension component <NUM> may provide a spring or shock-absorbing function and may, for example, dampen motion transfer between the wheels <NUM> and the chassis <NUM>.

The height adjustment mechanism <NUM>, comprising the height adjustment actuators <NUM>, <NUM>, is configured to shift the wheel attachment component <NUM> between a plurality of operating positions relative to the chassis attachment component <NUM>. As used herein, an "operating position" is a selectable position of the wheel attachment component <NUM> relative to the chassis attachment component <NUM> in which the distance between the attachment components <NUM>, <NUM> is rigidly or flexibly fixed. If the distance between the attachment components <NUM>, <NUM> is flexibly fixed, the relative positions of the attachment components may fluctuate but will return to the same operating position. Stated differently, the average distance between the attachment components <NUM>, <NUM> will remain the same even though the instantaneous distance may fluctuate above and/or below the average distance. Fluctuations in the relative positions of the attachment components <NUM>, <NUM> may result, for example, from operation of the suspension component <NUM>, operation of a hydraulic component, or both.

In operation, shifting the wheel attachment component <NUM> between operating positions relative to the chassis attachment component <NUM> will raise and lower the vehicle's chassis <NUM> between various operating positions relative to the ground surface. Each assembly <NUM> is operable to shift between two or more operating positions, such as, for example, between two, three, four, five, six, seven, eight, nine, ten, twelve, fourteen, or sixteen operating positions. Additionally, each assembly <NUM> may be infinitely adjustable between a first extreme operating position (<FIG>) and a second extreme operating position (<FIG>). The difference between the first extreme operating position and the second extreme operating position may be within the range of about <NUM> inches (<NUM>) to about <NUM> inches (<NUM>). More specifically, the difference may be about <NUM> inches (<NUM>), about <NUM> inches (<NUM>), about <NUM> inches (<NUM>), or about <NUM> inches (<NUM>).

As illustrated, the height adjustment actuators <NUM>, <NUM> are connected to the upper and lower chassis attachment members <NUM>, <NUM> and to the upper suspension member <NUM>, such that extending or retracting the height adjustment actuators <NUM>, <NUM> causes the upper suspension member <NUM> (and a top end or portion of the spring <NUM> to which it is connected) to shift up or down relative to the chassis attachment component <NUM>. The height adjustment actuators <NUM>, <NUM> may include fluid actuators and/or electro-mechanical actuators. By way of example, the height adjustment actuators <NUM>, <NUM> may include hydraulic cylinders that drive piston rods between retracted and extended positions.

As used herein, the suspension component <NUM> is "operably interposed" between the wheel attachment component <NUM> and the chassis attachment component <NUM> if it regulates motion transfer between the two components <NUM>, <NUM>. Thus, the suspension component <NUM> need not be positioned physically between the attachment components <NUM>, <NUM> in order to be operably interposed therebetween. As illustrated, the suspension component <NUM> may be positioned above (and in line with) both the wheel attachment component <NUM> and the chassis attachment component <NUM> and yet be operably interposed therebetween.

The assembly <NUM> is configured to pivot relative to the axle <NUM> to pivot a wheel coupled with the wheel attachment component <NUM> and steer the applicator <NUM>. The assembly <NUM> may pivot between a first extreme position (<FIG>) and a second extreme position (<FIG>) about an axis of rotation passing through, and defined by, the pivot element <NUM>. The extreme pivot positions may correspond to an angular separation of between, for example, about <NUM>° and about <NUM>°. The assembly <NUM> pivots as a single unit such that the wheel attachment component <NUM>, the chassis attachment component <NUM>, and the suspension component <NUM> pivot in unison, regardless of the position of the wheel attachment component <NUM> relative to the chassis attachment component <NUM>.

In the illustrated embodiment, the pivot element <NUM> attaches to an outer end of the axle <NUM>, the suspension component <NUM> is positioned above the axle <NUM>, and the wheel attachment component <NUM> is positioned below the axle <NUM> opposite the suspension component <NUM>. Furthermore, the wheel attachment component <NUM>, the chassis attachment component <NUM>, and the suspension component <NUM> lie on a line that corresponds to, or is parallel with, the axis of rotation of the assembly <NUM>.

The pivot element <NUM> may include a rotatory hydraulic actuator connected to the axle <NUM> and to the lower <NUM> and upper <NUM> chassis attachment members. The rotary hydraulic actuator selectively drives pivoting movement of the assembly <NUM> relative to the chassis <NUM>, and may be controlled by a vehicle operator or an automated guidance system to steer the applicator <NUM>.

By way of example, the rotary actuator may be a Helac L30 series helical hydraulic rotary actuator available from Parker Hannifin, Cylinder Division, of Des Plaines, Illinois, or a similar device. A rotary hydraulic actuator is a device manufactured to drive or induce rotational movement in response to hydraulic input. Thus, a portion of the rotary actuator rotates relative to another portion of the rotary actuator and does not require external connections or components to generate rotational motion. A rotary actuator may be designed, for example, to internally translate linear motion into rotational motion. In one exemplary embodiment, the rotary hydraulic actuator may generate output torque of between <NUM>,<NUM> foot-pounds (<NUM>,<NUM> N-m) and <NUM>,<NUM> foot-pounds (<NUM>,<NUM> N-m) at a hydraulic pressure of between <NUM>,<NUM> psi (<NUM> bar) and <NUM>,<NUM> psi (<NUM> bar) or, more specifically, may generate torque of between <NUM>,<NUM> foot-pounds (<NUM>,<NUM> N-m) and <NUM>,<NUM> foot-pounds (<NUM>,<NUM> N-m) at a hydraulic pressure of between <NUM>,<NUM> psi (<NUM> bar) and <NUM>,<NUM> psi (<NUM> bar). The rotary actuator may have a total angular displacement of between about <NUM>° and about <NUM>°.

The illustrated rotary hydraulic actuator <NUM> includes a plurality of spaced mounting feet or flanges <NUM> for securing to the axle <NUM> or other part of the chassis <NUM> and a cylindrical housing <NUM> with opposing ends that mount to, and rotate, the lower and upper chassis attachment members <NUM>, <NUM>. In the illustrated embodiment, the mounting feet <NUM> are configured to attach to a plurality of attachment points arranged in a planar configuration, such as on a single planar surface. Thus, the rotary actuator <NUM> may function both to mount the chassis attachment component <NUM> to the axle <NUM> and to rotate the assembly <NUM> relative to the axle <NUM> and, therefore, may simplify the design, manufacture, maintenance, and repair of the assembly <NUM> and related components. The housing <NUM> may have a diameter of between about <NUM> inches (<NUM>) and <NUM> inches (<NUM>) and a length of between about <NUM> inches (<NUM>) and about <NUM> inches (<NUM>). It will be appreciated by those skilled in the art that the rotary actuator <NUM> and the connections between the rotary actuator <NUM> and the assembly <NUM> and the axle <NUM> must be sufficiently strong to sustain the shock and rigors of routine use.

Rather than including a rotary actuator, the assembly <NUM> may include, or may be coupled with, another type of actuator such as a linear hydraulic actuator for driving pivoting motion. Alternatively, the assembly <NUM> may be configured to rigidly attach to the vehicle chassis <NUM> and not pivot relative to the chassis, wherein the chassis attachment component <NUM> is rigidly attached to the inner axle <NUM> or other portion of the chassis <NUM>. This may be desirable, for example, when the assembly <NUM> supports a ground-engaging element that is not intended to steer the applicator <NUM>. The chassis attachment component <NUM> may be rigidly attached to the axle <NUM> by replacing the pivot element <NUM> with a casting of the same size and shape as the pivot element <NUM> to rigidly connect to the chassis attachment component <NUM> and to the axle <NUM>. The assembly <NUM> may be configured to facilitate interchanging a rotary actuator configured to pivot the assembly and a static component configured to secure the assembly in a fixed position. Bolts or other easily removable attachment elements may be used to secure the rotary actuator <NUM> to the axle <NUM> and to the assembly <NUM> and may be positioned to facilitate access thereto. Thus, an actuator and a fixed element may both be provided with each of the assemblies <NUM> such that a user may interchange the actuator and the fixed element as desired.

In operation, the assemblies <NUM> raise and lower the chassis of the applicator <NUM>. More specifically, an operator may remotely control operation of the assemblies <NUM> to raise and lower the chassis <NUM> using, for example, one of the user interface elements forming part of the control environment <NUM> illustrated in <FIG>. Thus, the operator may raise and lower the chassis <NUM> while seated in the cabin <NUM>.

In one exemplary scenario, the operator fills the holding tank <NUM> at a central location, such as a local cooperative facility, and drives the applicator <NUM> to a field in a lowered operating position. Once at the field, the operator controls the assemblies <NUM> to raise the chassis <NUM> to a desired height to apply the product. The operator raises the chassis <NUM> while seated in the cabin <NUM>. When the application is complete or before the applicator <NUM> returns to the cooperative for additional product, the operator lowers the chassis <NUM> and drives the applicator <NUM> to the cooperative or to another field. Adjusting the height of the chassis <NUM> allows for safer travel to and from the field by lowering the applicator's center of gravity and overall height.

In another exemplary scenario, the applicator <NUM> and a tender vehicle are taken to an area of application, such as a field or group of fields. The applicator <NUM> is placed in a lowered chassis position and prepared by filling it with liquid chemical or other product to be applied to a crop. The tender vehicle may be configured to interface with the applicator <NUM> only when the applicator <NUM> is in a lowered chassis position. When the applicator <NUM> is prepared, the operator may drive the applicator <NUM> to a starting position, raise the chassis <NUM> to a desired height using one or more interface elements within the cabin <NUM>, and begin the application process. The operator refills the applicator <NUM> by returning to the tender vehicle, lowering the applicator chassis <NUM> to interface with the tender vehicle, and then raising the chassis <NUM> after the applicator <NUM> has been refilled to resume the application operation. When application for a first crop is complete, the applicator <NUM> may be used to apply a chemical to a second crop of a different height than the first crop. The operator may adjust the chassis height of the applicator <NUM> for application on the second crop, wherein a selected height for application on the second crop may be different than a selected height for application on the first crop.

With reference to <FIG> a method <NUM> of controlling the height adjustment mechanisms <NUM> may improve the ergonomic experience of the operator by reducing the occurrence of non-uniform chassis height adjustment. The method <NUM> involves monitoring the height signals and stopping any adjustment of a first support assembly if a differential in height signal of that assembly compared to any one of the other three support assemblies exceeds a predetermined tolerance value. In one embodiment, the method <NUM> is implemented by controller <NUM>. The description that follows is given in relation to only one of the wheels <NUM> and associated support assembly <NUM> but it should be understood that the method <NUM> may be executed simultaneously for each wheel <NUM> and associated support assembly <NUM> with height adjustment cylinder <NUM>. Reference is invited also to <FIG>, which illustrates most of the components involved in implementing the method <NUM> as described hereinafter.

In a first step <NUM>, the height signals from each of the height position sensors <NUM> are monitored to determine whether any adjustment of the height of that support assembly <NUM> is necessary. A target height position ht for each support assembly <NUM> may be received by the controller <NUM> from an operator via one of the user interface panels <NUM>, <NUM>. Alternatively, the controller <NUM> may determine a target height position ht for each support assembly <NUM> using a control algorithm having input parameters such as crop canopy height, vehicle speed, and/or topographical data. It should be understood that the target height position ht for each support assembly may differ from that of the other support assemblies.

The height signal for each support assembly <NUM> is representative of an actual height position ha. It should also be understood that the target height position ht and the actual height position ha as described herein is in relation to the relative positions between the wheel <NUM> of a given support assembly <NUM> and the chassis <NUM> as defined by the associated height adjustment actuator <NUM>, between the wheel attachment component <NUM> and the chassis attachment component <NUM> of the associated support assembly <NUM> described above.

If the actual height position ha-a for the first support assembly 22a is at, or within a predetermined range of, the target height position ht-a then no height adjustment of the first support assembly 22a is necessary and, as indicated at step <NUM>, the position of height adjustment cylinder 93a is maintained.

If, however, the actual height position ha-a for the first support assembly 22a is not at, or within a predetermined range of, the target height position ht-a then the controller <NUM> addresses the condition shown at step <NUM> in which the actual height position ha-a (as represented by the first height signal) is compared to the height signals corresponding to the other height adjustment cylinders 93b, 93c, 93d. If the actual height position ha-a of the first height adjustment cylinder 93a is within a height tolerance range hx then the first height adjustment cylinder 93a will be, or continue to be adjusted as per steps <NUM>-<NUM>.

If, however, the actual height position ha-a of the first height adjustment cylinder 93a is outside the height tolerance range hx, then movement of the first height adjustment cylinder 93a is stopped or prevented and the position is maintained. To represent algebraically, if <MAT> wherein ha-b,c,d is the average of the actual height positions of the other height adjustment cylinders 93b, 93c, 93d, then movement of the first height adjustment cylinder 93a is stopped or prevented and the position is maintained.

The tolerance range hx may be predetermined and stored by the controller <NUM>, and may be a constant value or proportional to the actual height position ha.

As set out at steps <NUM>-<NUM>, the direction of adjustment of the height adjustment cylinder 93a is determined by whether the actual height position ha-a is above or below the target height position ht-a.

The method <NUM> is executed continuously or periodically to prevent any substantial non-uniformity in chassis height adjustment. When a chassis height adjustment is executed, all height adjustment control valves <NUM> may be opened simultaneously to cause a flow of hydraulic fluid to or from the height adjustment cylinders <NUM> and raise all four corners of the chassis <NUM> together. However, hydraulic flow will inherently go to the path of least resistance. If less or no hydraulic flow passes one or more of the valves <NUM>, then a differential in height adjustment may occur between the height adjustment cylinders <NUM> and result in non-uniform adjustment. In operation, the method <NUM> advantageously intervenes to close the height adjustment control valve <NUM> associated with the fastest hydraulic flow (and thus the fastest adjustment as sensed by the sensors <NUM>) to force more flow through the other valves <NUM> and allow them to catch up.

With reference now to <FIG>, the track width of the applicator <NUM> is illustrated as the distance between the wheels 14a, 14b on a first side of the applicator <NUM> and the wheels 14c, 14d on a second side of the applicator <NUM>. As explained above, the applicator <NUM> includes a track-width adjustment system including telescoping axles <NUM>, <NUM> and actuators <NUM> (<FIG>) moving the inner axles <NUM> between extended and retracted positions. The track width may be infinitely adjustable between, for example, about <NUM> inches (<NUM>) and about <NUM> inches (<NUM>).

The applicator <NUM> may be configured such that the support assemblies <NUM> are not parallel with the direction of vertical movement of the chassis <NUM> when the support assemblies <NUM> are used to adjust the height of the chassis <NUM>. As illustrated in <FIG>, each support assembly <NUM> connects to the chassis <NUM> at a chassis connection point <NUM> and connects to one of the wheels <NUM> at a wheel connection point <NUM>. A straight line <NUM> interconnecting the chassis connection point <NUM> and the wheel connection point <NUM> is angled relative to vertical movement of the chassis <NUM> and is also angled relative to a vertical longitudinal axis of the wheel <NUM>. Line <NUM> represents the direction of vertical movement of the chassis <NUM> and the direction of the vertical longitudinal axis of the wheel <NUM>. This angled position of the assemblies <NUM> may be desirable for several reasons, including providing sufficient separation between the support assembly <NUM> and the wheel <NUM> and providing an optimal steering configuration.

As illustrated in <FIG>, the angled position of the assemblies <NUM> relative to the vehicle's frame presents certain challenges to use of the support assembly <NUM> to raise and lower the vehicle's chassis <NUM>. As the support assemblies <NUM> are actuated to raise the chassis <NUM>, for example, the wheels <NUM> are also pushed laterally outward away from the vehicle's chassis <NUM>. This may present a problem because some surfaces may prevent the wheels <NUM> from sliding relative to the chassis <NUM>, particularly if the applicator <NUM> is loaded with product. In these situations, the operator may be required to raise and lower the applicator <NUM> while the applicator <NUM> is travelling forward or backwards. Furthermore, it may be undesirable to operate the applicator <NUM> at a new track width such that the operator must re-adjust the track width to the desired amount each time he or she adjusts the height of the chassis <NUM>. As explained above, re-adjusting may conventionally be performed while the applicator <NUM> is moving.

To address the problems associated with lateral movement of the wheels <NUM> that occurs when the applicator height is adjusted, the control system <NUM> may be configured to automatically adjust the track width as the height of the applicator <NUM> is adjusted such that the wheels <NUM> do not move laterally relative to the ground surface as the applicator <NUM> is raised and lowered. With particular reference to <FIG>, if the support assembly <NUM> is positioned at an angle of inclination θ relative to the direction of travel of the chassis <NUM>, the change in lateral position of the wheel ΔW is defined as ΔW = sin(θ)×ΔH, where ΔH is the change in the distance between the chassis point of connection <NUM> and the wheel point of connection <NUM> along the line <NUM>. In this equation, ΔW represents the change in lateral position of one of the wheels <NUM> or, in other words, the wheels <NUM> on one side of the applicator <NUM>. The total change in track width is defined as twice that amount, or <NUM>×ΔW.

The control system <NUM> may be configured such that as the operator adjusts the height of the applicator <NUM> using, for example, a button or dial located in the cabin <NUM>, the control system <NUM> detects the height adjustment and automatically adjusts the track width accordingly to preserve the track width of the applicator <NUM>. Alternatively, the control system <NUM> may be configured to actuate both the chassis-height adjustment system and the track-width adjustment system. In this implementation, the user may adjust the chassis height via a user interface element, wherein the control system <NUM> actuates the height adjustment system to adjust the chassis height to the desired height and also adjusts the track-width system to preserve the track-width of the applicator. In either implementation, the control system <NUM> adjusts the track width according to the equation ΔW = sin(θ)×ΔH, explained above. Continuously or periodically, the controller <NUM> may determine a target track width wt based on this equation.

With reference to <FIG>, the height adjustment cylinders <NUM> and the track-width adjustment cylinders <NUM> share a common hydraulic circuit and pressure source <NUM>. When the height adjustment cylinders <NUM> and the track-width adjustment cylinders <NUM> are operated or commanded simultaneously as described above, hydraulic flow will inherently go to the path of least resistance. If less or no hydraulic flow passes one or more of the valves <NUM>, <NUM> then a differential in height and/or track width adjustment may occur and result in non-uniform adjustment. For example, the height of one or more support assemblies <NUM> may adjust faster than the track width, causing lateral scrubbing of the wheels across the ground as the chassis is raised or lowered.

In accordance with another embodiment shown in <FIG>, a method <NUM>' of operating the control system <NUM> advantageously intervenes to close or restrict the height adjustment control valve or valves <NUM> associated with the fastest hydraulic flow (and thus the fastest adjustment as sensed by the sensors <NUM>) to force more flow through the other valves <NUM>, <NUM> and allow them to catch up, thus improving the synchronization between all adjustment cylinders <NUM>, <NUM>.

The method <NUM>' is the same as the method <NUM> described above except that an additional condition is met before adjustment of the height adjustment actuators <NUM> is permitted. If the controller <NUM> determines at step <NUM> that the actual height position ha-a of the first height adjustment cylinder 93a is within a height tolerance range hx, then the controller <NUM> determines, at step <NUM>, whether the actual track width wa is within a track width tolerance range wx compared to the target track width wt.

The actual track width wa is calculated from the track-width signals generated by the track-width adjustment sensors <NUM>. As explained above, the target track width wt at any stage may be calculated based upon the actual height position ha using the relationship ΔW = sin(θ)×ΔH.

If the actual track width wa is within the track width tolerance range wx then the first height adjustment cylinder 93a will be, or continue to be adjusted as per steps <NUM>-<NUM>.

If, however, the actual track width wa is outside the track width tolerance range wx then movement of the first height adjustment cylinder 93a will be stopped or prevented and the position will be maintained. To represent algebraically, if <MAT> then movement of the first height adjustment cylinder 93a is stopped or prevented and the position is maintained.

In another embodiment, step <NUM> can be omitted from method <NUM>', and the chassis height adjustment of a given support assembly <NUM> is synchronized with the track width adjustment but not necessarily with the adjustment positions of the other support assemblies.

In summary a chassis-height adjustment system is configured for selectively raising and lowering a chassis relative to a ground surface. The system includes a plurality of support assemblies supporting a chassis on respective ground-engaging elements. Each support assembly has a height adjustment actuator. Height position sensors are provided to sense an adjustment position of a respective one of the height adjustment actuators and generate a height signal. Each of the support assemblies may be mounted to the chassis by a respective track-width adjustment mechanism having a track-width adjustment actuator which is configured to shift the position of the associated ground-engaging element laterally relative to the chassis. The height adjustment system is controlled in a manner to synchronize each height adjustment actuator with the other actuators. Adjustment of one or more height adjustment actuators is slowed or stopped in the event that other actuators need to catch up.

Claim 1:
A method of controlling a chassis-height adjustment system for selectively raising and lowering a chassis relative to a ground surface, the system comprising:
a chassis (<NUM>);
a plurality of ground-engaging elements (<NUM>) supporting the chassis above a ground surface;
a plurality of track-width adjustment mechanisms mounted to the chassis, each track-width adjustment mechanism comprising a telescoping axle (<NUM>, <NUM>) coupled with a respective one of the ground-engaging elements and a track-width adjustment actuator (<NUM>) configured to move each axle between a retracted position and an extended position;
a plurality of support assemblies (<NUM>) supporting the chassis on the ground-engaging elements and comprising a height adjustment actuator (<NUM>), wherein each support assembly defines a line of connection between a ground-engaging element attachment point (<NUM>) and a chassis attachment point (<NUM>), each line of connection defining a non-zero angle θ corresponding to an angle of deviation from a direction of vertical travel of the chassis;
a plurality of height position sensors (<NUM>) each disposed to sense an adjustment position of a respective one of the height adjustment actuators and generate a height signal representative of that adjustment position; and
a plurality of track-width position sensors (<NUM>), each disposed to sense an adjustment position of a respective one of the track-width adjustment actuators and generate a track width signal representative of that adjustment position;
the method comprising:
receiving a chassis-height adjustment command;
monitoring the height signal for each of the plurality of height adjustment actuators (<NUM>);
and characterized by:
comparing a first height signal corresponding to a first height adjustment actuator (<NUM>) to height signals corresponding to the other height adjustment actuators (<NUM>);
adjusting the first height adjustment actuator (<NUM>) only if the first height signal is within a height tolerance range with respect to the height signals that correspond to the other height adjustment actuators (<NUM>); and
adjusting the track-width adjustment actuators (<NUM>) to shift the corresponding ground-engaging element (<NUM>) a distance proportional to a change in the distance between the ground-engaging element attachment point (<NUM>) and the chassis attachment point (<NUM>).