Patent Publication Number: US-2021172149-A1

Title: Work machines including automatic grading features and functions

Description:
CROSS-REFERENCE 
     This is a continuation-in-part of U.S. application Ser. No. 16/686,639 filed Nov. 18, 2019, which is a continuation of U.S. application Ser. No. 16/378,814 filed Apr. 9, 2019 and now issued as U.S. Pat. No. 10,487,475, which is a divisional of U.S. application Ser. No. 15/943,070 filed Apr. 2, 2018 and now issued as U.S. Pat. No. 10,287,745, which is a continuation-in-part of U.S. application Ser. No. 15/484,695 filed Apr. 11, 2017 and now issued as U.S. Pat. No. 10,287,744, which claims the benefit of and priority to U.S. Application No. 62/322,030 filed Apr. 13, 2016, the disclosures of which are hereby incorporated by reference. 
    
    
     BACKGROUND 
     The present application relates generally to work machines including automatic or automated grading features and functions. Grading of earth or substrate is a necessary part of landscaping, grounds keeping, building and construction projects. Systems which automatically control the depth or position of a grading tool without requiring selection by an operator have been proposed. Heretofore, such systems have suffered from a number of drawbacks and disadvantages. There remains a significant need for the unique apparatuses, systems and methods disclosed herein. 
     DISCLOSURE OF ILLUSTRATIVE EMBODIMENTS 
     For the purposes of clearly, concisely, and exactly describing example embodiments of the disclosure, the manner and process of making and using the same, and to enable the practice, making and use of the same, reference will now be made to certain example embodiments, including those illustrated in the figures, and specific language will be used to describe the same. It shall nevertheless be understood that no limitation of the scope of the invention is thereby created, and that the invention includes and protects such alterations, modifications, and further applications of the example embodiments as would occur to one skilled in the art. 
     SUMMARY OF THE DISCLOSURE 
     One example embodiment is a work machine including a chassis, ground contacting members rotatably coupled with the chassis and one or more actuators coupled with the chassis. A receiver is coupled with the chassis and is structured to detect a wireless signal. An electronic controller is in operative communication with the receiver and the one or more actuators. The electronic controller is structured to adjust the one or more actuators in response to a wireless signal detected by the receiver. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating certain aspects of an example work machine including an automatic grading system. 
         FIGS. 2-6  are perspective views illustrating certain components of the automatic grading system of  FIG. 1  from alternate perspectives. 
         FIG. 7  is a perspective view of a grading position indication system in a first operational state. 
         FIG. 8  is a perspective view of the grading position indication system of  FIG. 7  in a second operational state. 
         FIG. 9  is a side sectional view of a portion of the grading position indication system of  FIG. 7 . 
         FIG. 10  is a side sectional view of a portion of a grading position indication system of  FIG. 7 . 
         FIG. 11  is a side view illustrating certain aspects of an example work machine including an automatic grading system. 
         FIGS. 12-14  are perspective views illustrating certain aspects of the work machine and the automatic grading system of  FIG. 11 . 
         FIGS. 15A-15E  are schematic illustrations of certain aspects of the automatic grading system of  FIG. 11  in different states of adjustment. 
         FIGS. 16A-16E  are side views of certain aspects the automatic grading system of  FIG. 11  in different states of adjustment. 
         FIG. 17  is a perspective view illustrating certain aspects of an example work machine including an automatic grading system in a first state of adjustment. 
         FIG. 18  is a perspective view illustrating certain aspects of the example work machine of  FIG. 17  in a second state of adjustment. 
         FIG. 19  is a front view of the example work machine of  FIG. 17  in the first state of adjustment. 
         FIG. 20  is a front view of the example work machine of  FIG. 17  in the second state of adjustment. 
         FIG. 21  is a top view of a portion of the example work machine of  FIG. 17  in the first state of adjustment. 
         FIG. 22  is a top view of a portion of the example work machine of  FIG. 17  in the second state of adjustment. 
         FIG. 21  is a top view of a portion of the example work machine of  FIG. 17  in the first state of adjustment. 
         FIG. 22  is a top view of a portion of the example work machine of  FIG. 17  in the second state of adjustment. 
         FIG. 23  is a perspective view of a portion of another form of the example work machine of  FIG. 17 . 
         FIG. 24  is a perspective view of a portion of the example work machine of  FIG. 17  in the second state of adjustment. 
         FIGS. 25A, 25B, and 25C  are partially schematic front views of one form of a portion of the example work machine of  FIG. 17  in several states of adjustment. 
         FIGS. 26A, 26B, and 26C  are partially schematic front views of another form of a portion of the example work machine of  FIG. 17  in several states of adjustment. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     With reference to  FIG. 1 , there is illustrated a perspective view of an example work machine  100  operatively coupled with an automatic grading system. In the illustrated embodiments, work machine  100  is a light-duty work machine with a substantially zero turning radius. It shall be appreciated, however, that other types of work machines may also be utilized in connection with the automatic grading systems and components disclosed herein. 
     Machine  100  is one example of a self-propelled light-duty work machine. In a preferred embodiment work machine  100  has a weight of about  1100  pounds and a propulsion system comprising a rated power of 18 hp or less. Additional embodiments comprise self-propelled light-duty work machines including a propulsion system comprising a rated power of 25 hp or less, weighing 1500 pounds or less, or comprising both of said attributes. Further embodiments comprise self-propelled light-duty work machines including a propulsion system comprising a rated power of 30 hp or less, weighing 2000 pounds or less, or comprising both of said attributes. 
     Work machine  100  includes a chassis supported by front wheels  104  and rear wheels  106  which contact a ground surface and support the chassis. As will be understood by a person of skill in the art the front wheels  104  and the rear wheels  106  are examples of ground contacting members rotatably coupled with the chassis of work machine  100 . In the illustrated embodiments the chassis is configured to provide an example frame structure with which various work machine elements and tool elements are coupled. It shall be appreciated that the chassis of work machines according to other embodiments may comprise a variety of structures including frame-based chassis, unibody chassis, or other types of chassis or support structures that are configured to be supported by ground contacting wheels or other ground contacting members and coupled with one or more soil working tools. 
     In the illustrated embodiment the front wheels  104  of work machine  100  are configured as caster type wheels which preferably are rotatable 360 degrees relative to the chassis. It shall be appreciated that a variety of differently configured front wheels  104  may be utilized including, for example, front wheels provided on an axle, rack, and pinion assembly, or other types of front end steering assembly and/or front end drive assembly. It shall be further appreciated that additional embodiments may include only a single front wheel, a greater number of front wheels, or may include ground surface contacting elements other than wheels, such as treads or tracks. While the front wheels  104  are non-driven wheels in the illustrated embodiments, it shall be appreciated that other embodiments comprise one or more driven front wheels configured to provide at least part of the propulsion to the work machine. 
     In the illustrated embodiments the rear wheels  106  of work machine  100  are coupled with a machine prime mover. In a preferred embodiment, the prime mover comprises an internal combustion engine configured to drive a hydraulic pump that is flow coupled with a hydraulic drive system configured to provide torque to the rear wheels  106 . Example hydraulic drive systems may include elements such as high-pressure accumulators, low-pressure reservoirs, secondary pumps, gearboxes, collectors, and/or differentials. In other embodiments, the prime mover is configured as an internal combustion engine configured to provide driving torque through an output shaft. In other embodiments, the prime mover comprises an internal combustion engine and/or an electric motor configured to provide output torque. The electric motor may be powered by a battery or other power storage source, by a generator driven by an internal combustion engine, or a combination thereof. 
     In the illustrated embodiments each of the rear wheels  106  is independently controllable and drivable in a forward or reverse direction, though other embodiments may comprise different drive wheel arrangements, including front-wheel drive arrangements, all-wheel drive and four-wheel drive arrangements, to name several non-limiting examples. Certain embodiments may comprise only a single rear-wheel or a greater number of rear wheels  106  or other ground contacting members. Certain embodiments may include additional driven ground contacting wheels, for example, two ground contacting wheels may be provided on truck structures provided on either side of and pivotally coupled with the work machine in a tandem walking arrangement, and each of the four overall ground contacting wheels may be independently driven by a hydraulic motor or an electric motor. 
     The chassis supports an operator station  112  which includes a standing platform and a guard rail positioned at the aft end of work machine  100  adjacent the standing platform. Operator controls  150  are positioned to be manipulatable by an operator occupying the operator station  112  in order to control movement or propulsion of the work machine  100  as well as the positioning of one or more tools carried by the work machine as further described herein. It shall be appreciated that operator controls  150  may include one or more levers or other operator manipulatable controls that are operatively coupled with valves and hydraulic fluid lines to control one or more hydraulic actuators of the work machine. For clarity of illustration these features have not been depicted in the illustrated embodiments. Furthermore, in certain embodiments, the operator station  112  may comprise an operator seat instead of or in addition to a standing platform. In certain embodiments the operator station  112  may be omitted and the machine may be controlled remotely using a separate operator control station in wireless communication with a controller provided on the machine  100  and configured to control movement or propulsion of the machine  100  as well as the positioning of one or more tools carried by the work machine. 
     With reference to  FIGS. 1-6 , there are illustrated several views of various components of the example automatic grading system which is operatively coupled with work machine  100  in the view of  FIG. 1  and separately from various components of work machine  100  in the views of  FIGS. 2-6 . The automatic grading system includes a tool mount  120  which is operatively coupled with a grading tool assembly including finishing box  170  and scarifying shanks  190 . In the illustrated embodiments, scarifying shanks  190  are attached to tool mount  120  and finishing box  170  is attached to finishing comb  138  which is in turn attached to tool mount  120  as is further described below. In this form, finishing comb  138  may be considered as both a tool component and a tool mount component. Other embodiments contemplate different configurations for tool mount  120  and the tool components coupled therewith, for example, finishing box  170  may be coupled directly with tool mount  120  or intermediately coupled to tool mount  120  by various other intermediate structures. Similarly, scarifying shanks  190  may be coupled with tool mount  120  in other locations or directly coupled with other components which are, in turn, coupled with tool mount  120 . Furthermore, tool mount  120  may be provided with different dimensions and shapes as the illustrated form. 
     Finishing box  170  includes rear wall member  174  extending a distance along the width of the work machine  100  in the X-axis direction and side wall members  172  extending a distance along the length of the work machine  100  to a location forward from the rear wall in the Y-axis direction. Rear wall member  174  includes a lower toothed edge in the illustrated embodiments but may also be provided with a straight edge. Member  176  extends a distance along the width of the work machine  100  in the X-axis direction and is coupled with rear wall member  174 . Members  178  are attached to member  174  and are positioned at a distance from one another and structured with angled portions to provide a surface over which the wheels or other ground contacting members of work machine  100  can travel to facilitate work machine  100  driving over finishing box  170  during connection or disconnection of the grading tool assembly. Members  180  are attached to member  176  and side wall members  172 . The bottom surface of members  180  is configured to rest against finishing comb  138 . Attachment members  182  include a portion structured and positioned to pass through a gap intermediate teeth of finishing comb  138  and an attachment mechanism  182  structured to selectably clamp members  180  to finishing comb  138 . In the illustrated embodiments, attachment mechanism  182  is structured to include nut with handles to facilitate attachment of the finishing box  170  to the comb  138  without specialized tools, or with minimal use of tools such as a pipe extension for applying additional torque to the attachment mechanism. 
     Scarifying shanks  190  are coupled with tool mount  120  and positioned forward from the rear wall member in the Y-axis direction and between the side wall members in the X-axis direction. Scarifying shanks  190  are one example of ground penetrating members which may be provided in a grading tool assembly. During operation of the grading tool assembly, scarifying shanks penetrate the ground surface ahead of rear wall member  174  and disrupt and loosen the earth through which they path. Rear wall member  174  and side wall members  172  form a container structured that collects and moves the loosened earth. 
     By varying the height of the grading tool assembly in the Z-axis direction, finishing box  170  and scarifying shanks  190  can be utilized to grade the underlying ground surface to a selectably height. By varying the pitch of the grading tool assembly relative to the X-Y plane, the amount of earth collected and released by finishing box  170  can be varied. By adjusting the pitch so that end wall member  174  rotates toward the earth being graded, finishing box  170  can be adjusted to increase earth collection and transport. By adjusting the pitch so that end wall member  174  rotates away from the earth being graded, finishing box  170  can be adjusted to decrease earth collection and transport. It shall be appreciated that pitch adjustment can occur while maintaining a given height adjustment or concurrently with a height adjustment as further described herein. 
     During pitch adjustment of the grading tool assembly the depth of penetration into the earth of scarifying shanks  190  will also vary. By adjusting the pitch so that end wall member  174  rotates toward the earth being graded, scarifying shanks  190  rotate so that they penetrate the earth to a lesser depth (or are extracted entirely). The coordinated rotation of finishing box  170  and scarifying shanks  190  in this direction reduces earth loosening and increases earth transport. This permits increases in earth transport while also reducing propulsion opposing force attributable to the scarifying shanks  190 . By adjusting the pitch so that end wall member  174  rotates away from the earth being graded, scarifying shanks  190  rotate so that they penetrate the earth to a greater depth. The coordinated rotation of finishing box  170  and scarifying shanks  190  in this direction increases earth loosening and decreases earth transport. This permits increases in earth disruption while also reducing propulsion opposing force attributable to the finishing box  170 . 
     Tool mount  120  and the grading tool assembly coupled therewith including finishing box  170  and scarifying shanks  190  are moveable relative to the chassis of work machine  100  in several manners including translational movement generally in the direction of the Y-axis, translational movement generally in the direction of the Z-axis, and rotational movement about an axis generally parallel with the X-axis direction. Tool mount  120  is coupled with an actuator  142  at a pivotable coupling. Actuator  142  is also coupled with the chassis of work machine  100  at a pivotable coupling. In the illustrated embodiments actuator  142  is configured as a hydraulic cylinder which is laterally expandable and contractible generally in the Y-axis direction. The operator controls  150  may be configured to control the supply of pressurized hydraulic fluid to actuator  142  to control its position. 
     Tool mount  120  is connected to rocker  124  by a chain  121  or another flexible rigging member. Rocker  124  is coupled with actuator  140  at a pivotable coupling. Actuator  140  is also coupled with the chassis of the work machine  100  at a further pivotable coupling. In the illustrated embodiments actuator  140  is configured as a hydraulic cylinder which may be controlled in the same or similar fashion as actuator  142 . It shall be appreciated that either or both of actuators  140  and  142  may be provided in different configurations, for example, as ratchets, top links or other actuators configured to provide appropriate displacement and force. It shall further be appreciated that either or both of actuators  140  and  142  may be omitted in certain embodiments. In such embodiments vertical adjustment of a tool mount is preferably, though not necessarily, provided by actuators configured to adjust other structural elements of a machine, for example, adjustable wheel suspension elements configured to raise or lower a chassis or other structure supporting, directly or indirectly a tool mount, or via a variety of other actuators. 
     In the illustrated embodiments actuator  140  is selectably controllable to expand and contract in the Y-axis direction effective to cause rocker  124  to rotate relative to the chassis about an axis parallel with the X-axis direction. Rotation of the rocker  124  is effective to raise and lower the tool mount  120  with the chain  121  over a first predetermined range from a maximum height to the point at which the support wheels  104 ,  106  contacts the ground surface underlying the machine  100 . Support wheels  104 ,  106  are structured to ride along the underlying ground surface and limit further downward motion of the tool mount  120  and structured coupled thereto while concurrently allowing further rotation of the rocker  124  to compress or decompress the springs  126  or other elements of suspension  125 . Thus, rotation of the rocker  124  is effective to vary the amount of spring action force applied to the tool mount  120  by varying the compression of springs  126  without substantially changing the Z-axis position of the tool mount  120 . The suspension  125  accommodates movement of the tool mount in response to external force applied thereto, for example, if the tool mount contacts an obstruction such as a rock or other structure located in a soil medium being worked. 
     It shall be appreciated that chain  121  is one example of a weight lifting structure that may be utilized to raise and lower a soil working tool or tool mount. Structures such as cables, jointed linkages and other structures that limit relative displacement of a tool relative to a support structure to allow lifting through actuation in one direction, and deform, bend, flex, move or otherwise accommodate movement. It shall be further appreciated that chain  121  (or other lifting member(s)) may be to provide different and variable preloading of the springs or compressible members of suspension  125 . 
     Actuator  142  is selectably controllable to expand and contract generally in the Y-axis direction effective to cause tool mount  120  to rotate relative to the work machine about an axis generally parallel with the X-axis direction as indicated by arrow RM. In this manner the pitch of the tool mount X-Y plane may be varied. This rotation can be utilized to rotate the grading tool assembly (raising one end and lowering the other) relative to the underlying ground surface and to control the force it applies to the underlying ground surface in the Z-axis direction. 
     Tool mount  120  is further coupled with a suspension  125  by a pivotable coupling. The suspension  125  is in turn connected to rocker  124  at a pivotable coupling. Rocker  124  is further coupled with the chassis at a pivotable coupling. In the illustrated embodiments the suspension  125  is configured as a pair of telescoping cylinders in combination with springs  126  which are compressible between spring mounts through relative motion of the telescoping cylinders. It shall be appreciated that a variety of other suspensions may be utilized in various embodiments in addition to or instead of the illustrated configuration including shock absorbers, elastomeric suspension elements, compressible members, pneumatic suspension elements, hydraulic suspension elements, other spring arrangements and combinations of the foregoing and/or other suspension elements. It shall be further appreciated that a variety of springs and spring mounts may be utilized. In the illustrated embodiments springs  126  are helical and the spring mounts are crimped or compressed in place relative to respective shafts or cylinders of a telescoping assembly. In certain embodiments the spring mounts may alternatively or additionally be welded, bonded, bolted or otherwise fixedly coupled with respective suspension elements. Certain embodiments comprise spring mounts adjustably coupled with respective suspension elements, for example, through an axial threaded connection which may utilize one or more lock nuts or other locking members, or by a set screw, pin or bolt. 
     The tool mount  120  is further coupled with a pulling linkage  130  at a pivotable coupling which rotates generally about an axis in parallel with the X-axis direction. Pulling linkage  130  is coupled with the chassis of the work machine at a pivotable coupling which rotates about an axis in parallel with the X-axis direction. Pulling linkage is configured to provide a force vector component to the tool assembly in the forward or reverse Y-axis direction as the machine is propelled forward or backward. A force vector component generally in the Y-axis direction may also be provided, for example, during turning of the machine. Regardless of the particular direction, the pulling linkage provides one or more force vector components providing working force to the tool assembly. Furthermore, the rotation permitted by pivotable couplings between pulling linkage and the chassis of the work machine accommodates both adjustment of the height and pitch of the tool assembly relative to the X-Y plane. 
     The above-described motion of tool mount  120  and the grading tool assembly can be controlled in an automated manner by an electronic control system. In the illustrated embodiments, the electronic control system includes a receiver  192  coupled with suspension element  125  by a positioning pole  194  and an electronic controller  195  in operative communication with receiver  192 , actuator  140 , and optionally with actuator  142 . Receiver  192  is moveable relative to and can be fixed in place in a plurality of positions along pole  194  in the Z-axis direction. This adjustability allows the receiver to be positioned relative to a reference signal source such as a rotating laser. Accordingly, in some forms receiver  192  may be structured as a laser receiver adapted to receive a laser beam output by a laser level apparatus, for example, a rotary laser, a single plane laser, a dual plane laser, a conical laser or a GPS laser. In other forms receiver  192  may be provide as or in combination with other types of wireless signal sources and signal detectors or receivers. 
     Electronic controller  195  may be structured as a microprocessor-based or microcontroller-based electronic control unit and may include wired input circuitry for receiving input from receiver  192  and/or wireless communication circuitry for receiving input from receiver  192 . Electronic controller  195  may be configured to evaluate a reference signal, such as a laser beam received by receiver  192 , and to determine actuator position adjustment commands based upon the received reference signal(s) and one or more operator-specified grading commands input to the electronic controller  195 . The operator-specified grading commands input to the electronic controller may include a Z-axis grade elevation and a grade angle and direction which may be defined relative to the X-Y plane or another reference plane. Electronic controller may further include output circuitry adapted to provide commands to one or more actuators for adjustment of a working tool in accordance with the determined actuator position adjustment commands, for example, commands to operate a hydraulic actuator or a proportion valve of a hydraulic actuator or an electric actuator. 
     Electronic controller  195  may be structured to output control commands to adjust actuator  140  which is effective to simultaneously adjust the position of the receiver in the Z-axis direction and one or both of the position of the grading tool assembly in the Z-axis direction and the force applied to suspension  125  in the Z-axis direction. The degree to which the Z-axis position of the grading tool and/or the Z-axis force applied to suspension  125  are varied depends upon whether and the degree to which the grading tool assembly encounters resistance force in response to the automated control of actuator  140  by electronic controller  195 . The force applied to suspension  125  in the Z-axis direction is effective to apply force to the grading tool assembly in the Z-axis direction thereby providing working force on the underlying ground surface toward the operator-specified grading commands. Additionally, it shall be appreciated that receiver  192  and pole  194  are fixedly coupled to a structure of suspension  125 , such as suspension member  128 , which continues to move in response to adjustment of actuator  140  as springs  126  is compressed and that motion of the grading tool assembly and suspension elements fixedly coupled thereto, such as suspension member  127 , can de-couple from and vary relative to the motion of receiver  192  and pole  194  due to compression of springs  126 . 
     In a system rigidly or fixedly interconnecting a grading tool and a receiver, the aforementioned motion and force application would result in motion of the grading tool assembly of a magnitude and direction equivalent to the motion of receiver  192 . In contrast, in the illustrated embodiment the suspension  125  is compressible to vary the distance between the receiver  192  and the grading tool assembly depending upon the working force encountered by the grading tool assembly. Surprisingly, allowing the depth or position of the grading tool to vary from the position that would normally be selected using the electronic grading system has been determined to provide unique benefits and operability for light duty work machines notwithstanding the fact that it would appear contrary to the goal of automated grading depth positioning. By selecting the compression characteristics of suspension  125  relative to the weight and power of the work machine, the compression may be effective to avoid exceeding the propulsion system power output and stopping the work machine. This additional degree of freedom provides a synergistic functionality allowing automatic adjustment of the position of the grading tool assembly while also permitting variation from the automatic depth to avoid undesired stoppage of the work machine. 
     An additional degree of freedom is provided by actuator  142  which may be controlled to vary grading tool assembly pitch concurrently with the automatic height adjustment of the actuator  140 . This allows the operator to manipulate operator controls  150  to vary the pitch of the grading tool assembly effective to vary the relative earth disrupting and earth moving functions of the grading tool assembly while simultaneously providing automatic adjustment of the overall grading depth as described above. It shall be appreciated that operator pitch adjustment may be performed concurrently with automatic height/depth adjustment by the electronic control system thus providing the operator with the ability to adjust the earth disruption and transport characteristics of the finishing box  170  while concurrently automatically controlling toward a uniform grading height. Such automated adjustment may be in response to an operator-input grade angle or elevation provided to electronic controller  195 . 
     With reference to  FIGS. 7-10  there are illustrated further details of sighting gauge system  202  and its interconnection with suspension  125 . Sighting gauge system  202  includes an outer member  204  and an inner member  206  which is moveable relative to inner member  206  in the direction generally illustrated by arrow  229 . Outer member  204  is structured to be adjustably coupled with suspension member  128  at one end and to slidably receive inner member  206 . Outer member  204  is adjustably coupled with suspension member  128  by a set screw  231  which passes through an opening  233  defined in outer member  204  and engages a threaded opening provided in suspension member  128 . Set screw  231  may be tightened to retain outer member  204  in a fixed position relative to suspension member  128  and loosened to permit adjustment of outer member  204  relative to suspension member  128  in the direction generally indicated by arrow  229 . It shall be appreciated that sighting gauge system  202  is one example of a grading position indication system which is structured to provide a visually perceptible qualitative and quantitative indication of a difference between an automatic or automated commanded grading position for a grading tool and an actual position for the grading tool. In certain applications, sighting gauge system  202  is visible not only by a tool operator but also by bystanders up to 100 feet or greater distant from the vehicle. 
     The range of adjustability of outer member  204  relative to suspension member  128  may be defined by the upper and lower surfaces of opening  233  which come into contact with set screw  231  at respective maximum and minimum vertical adjustment positions. In some forms a gap may remain between outer member  204  and suspension member  128  in the downward most position. In some forms the stepped inner surface of outer member  204  may come into contact with suspension member  128  in the downward most position. It shall be appreciated that the extent and position of opening  233  and the portion of outer member  204  in which it is provided may vary from the illustrated embodiment, for example, the opening  233  may extend downward in a greater distance to allow increased range of adjustment. The adjustable mating and coupling between outer member  204  and suspension member  128  may also comprise additional or alternate coupling and fixation structures such as additional or alternate threaded connections, detent connections, and removable pin connections to name several examples. For example, in the embodiment illustrated in  FIG. 10 , set screw  331  is threaded into collar  338  which extends from outer member  304 . In this embodiment set screw  331  may be tightened to provide contact force against the outer surface of suspension member  328  to fix outer member  304  in place relative to suspension member  328  and loosened to permit outer member  304  to move relative to suspension member  328 . It shall be appreciated that outer set screw  331 , outer member  304  and suspension member  328  correspond generally to set screw  231 , outer member  204  and suspension member  128  in regards to their functionality and relationship to other structures of the overall apparatus and system. It shall be further appreciated that the embodiment illustrated in  FIG. 10  may be provided in connection with the other features of work machine illustrated in  FIGS. 1-9  as an alternate form of sighting gauge system  202 . 
     Inner member  206  is structured to abut suspension member  127  at one end and to slide relative to outer member  204 . Inner member  206  may be maintained in abutment with suspension element by its own weight and/or by a mechanical coupling structure. In some forms inner member  206  may be fixed to or integrally formed with suspension member  127  to provide a unitary structure. Inner member  206  is structured to move with suspension member  127  effective to vary the relative position between inner member  206  and outer member  204 . This variation in relative position provides a visually perceptible indication of a measurement of the extent to which a desired or commanded grading result needs or remains to be accomplished. In the illustrated embodiment, inner member is configured to move between a lower position which is illustrated in  FIG. 8  and is also denoted by dashed line  206 A in  FIG. 7 , and an extended upper position which is illustrated in  FIGS. 7 and 9 . With respect to the embodiment illustrated in  FIG. 10 , inner member  306  corresponds to inner member  206  and is moveable between the position illustrated in  FIG. 10  and the position generally indicated by dashed line  306 A which corresponds to dashed line  206 A. 
     As discussed above in connection with  FIGS. 1-6 , springs  126  of suspension  125  may be compressed during operation of work machine  100  when electronic controller  195  automatically adjusts actuator  140  downward. During such adjustment, the relative positions of suspension member  128  and suspension member  127  may vary. Since suspension member  128  is fixedly (through rotatably) coupled with actuator  140  by rocker  124 , its position varies in a generally fixed relationship to the motion of actuator  140 . On the other hand, suspension member  127  is non-fixedly coupled with actuator  140  and may travel upward relative to suspension member  128  in response to compression of springs  126 . The relative position between suspension member  127  and suspension element  128  is correlated to and may be substantially equal to a measurement of the extent to which the grading position that is commanded by controller  195  has actually been accomplished. The indication of a measurement of the extent to which a desired or commanded grading result needs or remains to be accomplished is thereby visible through the relative position of outer member  204  and inner member  206  or outer member  304  and inner member  306 . 
     As illustrated in  FIG. 7 , a suspension lockout feature is provided and may be selected by inserting retaining pin  221  into an opening  223  formed in suspension member  128  and an opening formed in suspension element  127  disposed within suspension member  128 . The opening formed in suspension element  127  may be selected and sized such that the alignment with opening  223  formed in suspension member  128  occurs when the suspension  125  is substantially uncompressed. At the same time, the position of outer member  204  may be adjusted to be substantially even with the upper extremity of inner member  206 . In this configuration the upper end surface of inner member  206  will extend upward from the upper end surface of outer member  204  when the suspension  125  is compressed and will lie substantially even with the upper end surface of the outer member  204  when the suspension is relaxed or fully extended. This configuration provides a visual indication of the extent of compression of the suspension  125  which is visually perceptible by the operator of work machine  100  as well as operators of other work machines in the vicinity thereof. In some forms, the lockout feature may be structured such that retaining pin  221  passes entirely through outer member  204  and inner member  206 . Preferably the lockout feature is employed when the desired grade is nearly completed, for example, within about ¼ inch, to avoid the possibility that premature lockout may cause the tool to lose traction. In some forms retaining pin  221  may be configured to outer member  204  and inner member  206  at an angle relative to the vertical surfaces of outer member  204  and inner member  206 . An external holder may be provided to store retaining pin  221  when the lockout mode is not engaged. Clips or retention rings may also be engaged with retaining pin  221  to maintain retaining pin  221  in the installed position and prevent inadvertent removal. It shall be appreciated that retaining pin is one example of a suspension lockout member adapted to maintain suspension  125  in a fixed position. Additional examples of suspension lockout members include screws, detent mechanisms, clips, collars bolts and other structures adapted to engage suspension member  128  and suspension member  127  and maintain them fixed relative to one another. 
     Sighting gauge system  202  may be calibrated or adjusted by an operator in conjunction with the set-up of work machine  100  and the provision of operator-specified grading commands input to the electronic controller  195 . The calibration may be performed such that the suspension  125  assumes its relaxed or extended position when the position corresponding to the operator-specified grading commands has been achieved. In such a calibration state, the position of inner member  206  or  306  relative to outer member  204  or  304 , respectively, provides an indication of the distance between the current grading state of the underlying ground surface and the desired grading state of the underlying ground surface as defined by the operator-specified grading commands. It shall be further appreciated that this indication is both qualitative and quantitative in that the distance that inner member  206  or  306  extends above outer member  204  or  304  corresponds to and may be calibrated to be substantially identical to the depth of grading that must still be performed to provide the desired grading state of the underlying ground surface as defined by the operator-specified grading commands. Thus the relative position of inner member  206  or  306  relative to outer member  204  or  304  provides a visually perceptible indication of the progress toward an operator-specified grading state of the underlying grounds surface and this indicia is perceptible to the operator of the work machine as well as in a line of sight path in all directions, for example, by a bystander within 100 feet or more. 
     Outer member  204  includes a sighting gauge notch  205  which permits the relative position of inner member  206  and outer member  204  to be visually perceived by an operator or worksite observer even when inner member  206  is positioned below outer member  204 . While outer member  204  is illustrated as having one U-shaped sighting gauge notch, it shall be appreciated that additional sighting gauge notches may be provided at other locations about outer member  204  to provide visibility from additional viewing positions. Furthermore, the size and shape of the sighting gauge notch may vary from the illustrated embodiments and may be, for example, a V-shaped notch, a rectangular notch, or a series of holes or apertures provided along a length of outer member  204 . It shall be further appreciated that shading or color contrast between inner member  206  and outer member  204  may be provided to enhance the visual perceptibility of their relative positioning and changes thereof. 
     It shall be appreciated that the visually perceptible indicia discussed above provides unique synergistic benefits in combination with the aforementioned automated or automatic height or depth adjustment capabilities. Such features allow the operator of a first work machine, such as work machine  100 , to judge the extent to which a desired depth or height position commanded by the automatic or automated depth or height adjustment is being reached and a corresponding extent to which the suspension assembly is being compressed thereby providing an ability to determine and judge progress toward an operator defined grading state of the underlying ground surface. The visually perceptible indicia are further available to and perceivable by operators of additional work machines in the vicinity. Operators of these additional work machines my thereby take advantage of the automated grading depth control features of the first work machine without requiring those features and the apparatuses and systems provided on them to be provided on the additional work machines. Furthermore, coordinated operation of the first work machines and additional work machines of different types is enabled by this combination of features and can improve the speed and efficiency with which a grading operation may be completed. 
     In one example process, an athletic field or arena, such as a baseball diamond or equine arena, may be constructed or refurbished by grading with a first work machine such as work machine  100  configured to provide automated operator specified grade characteristics and by one or more additional heavier duty work machines such as a front loader, bucket vehicle or other earth moving equipment. The operators of the additional heavier duty work machines may observe the visually perceptible indicia and may qualitatively and quantitatively judge and determine progress toward the operator defined final grading state. The operators of the additional heavier duty work machines may therefore determine and judge areas of the underlying ground surface where additional grading is needed and may selectively and strategically utilize the greater earth moving capabilities afforded by heavier duty machines to target those areas where ground surface moving or removal is needed to achieve the desired grading result. Once a certain amount of progress is made, e.g., the target grade has been established to about ¼ inch, the lockout feature of the first grading tool may be engaged and the first grading tool may be utilized to complete a final finish grading operation to achieve the desired grading result. 
     With reference to  FIGS. 11-14, 15A-15E and 16A-16E , there are illustrated several views of certain aspects of an example work machine  101  operatively coupled with an example automatic grading system. Work machine  101  and its example automatic grading system include a number of features that are the same as or similar to the features described above in connection with work machine  100  and its example automatic grading system, and a number of such features are indicated with like reference numerals in both work machine  100  and work machine  101 . While certain such common features are illustrated in the drawings and described below, it shall be appreciated that all aspects, alternatives and variations described or illustrated in connection with work machine  100  also apply to and may be embodied in work machine  101  unless described to the contrary. Work machine  101  and its example automatic grading system also include certain aspects which differ or vary from those of work machine  100  a number of which are illustrated in connection with  FIGS. 11-14, 15A-15E and 16A-16E  and described below. 
     Like the automatic grading system of work machine  100 , the automatic grading system of work machine  101  includes a tool mount  120  which is connected to rocker  124  by a chain  121 . Rocker  124  is coupled with actuator  140  at a pivotable coupling  408  which is visible in the figures illustrating work machine  101  and described above although not visible in the figures illustrating work machine  100 . Actuator  140  is also coupled with the chassis of the respective work machine  100  or  101  at a further pivotable coupling and is selectably controllable to expand and contract in the Y-axis direction effective to cause rocker  124  to rotate relative to the chassis about an axis parallel with the X-axis direction. Rocker  124  includes outer members  402  which are coupled with suspension  125 . Rocker  124  also includes a shaft member  404  which extends between and is coupled with the outer members and is coupled with pivotable coupling  408 . Rocker  124  further includes an actuator connector  406  which is pivotally coupled with shaft member  404  and actuator  140 . Rocker  124  further includes a lifting connector  358  which is pivotally coupled with shaft member  404  and chain  121 . 
     As described above, rotation of the rocker  124  is effective to raise and lower the tool mount  120  with the chain  121  over a first predetermined range from a maximum height to the point at which the support wheels  104 ,  106  contacts an underlying ground surface and are structured to ride along the underlying ground surface and limit further downward motion of the tool mount  120  and structured coupled thereto while concurrently allowing further rotation of the rocker  124  to compress or decompress the springs  126  or other elements of suspension  125 . Thus, rotation of the rocker  124  is effective to vary the amount of shock absorption force applied to the tool mount  120  by varying the compression of springs  126  without substantially changing the Z-axis position of the tool mount  120 . The suspension  125  accommodates movement of the tool mount in response to external force applied thereto, for example, if the tool mount contacts an obstruction such as a rock or other structure located in a soil medium being worked. 
     Actuator  142  is selectably controllable to expand and contract generally in the Y-axis direction effective to cause tool mount  120  to rotate relative to the work machine about an axis generally parallel with the X-axis direction as indicated by arrow RM. In this manner the pitch of the tool mount X-Y plane may be varied. This rotation can be utilized to rotate the grading tool assembly (raising one end and lowering the other) relative to the underlying ground surface and to control the force it applies to the underlying ground surface in the Z-axis direction. Tool mount  120  is further coupled with a suspension  125  by a pivotable coupling. The suspension  125  is in turn connected to rocker  124  at a pivotable coupling. Rocker  124  is further coupled with the chassis at a pivotable coupling. Tool mount  120  is further coupled with a pulling linkage  130  at a pivotable coupling which rotates generally about an axis in parallel with the X-axis direction. Pulling linkage  130  is coupled with the chassis of the work machine at a pivotable coupling which rotates about an axis in parallel with the X-axis direction. Pulling linkage is configured to provide a force vector component to the tool assembly in the forward or reverse Y-axis direction as the machine is propelled forward or backward. A force vector component generally in the Y-axis direction may also be provided, for example, during turning of the machine. Regardless of the particular direction, the pulling linkage provides one or more force vector components providing working force to the tool assembly. Furthermore, the rotation permitted by pivotable couplings between pulling linkage and the chassis of the work machine accommodates both adjustment of the height and pitch of the tool assembly relative to the X-Y plane. 
     The automatic grading system of work machine  101  includes a pole assembly  350  which includes an upper pole member  364 , a middle pole member  363  and a lower pole member  354 . Upper pole member  364  receives and is adjustably coupled with middle pole member  363  by set screws  367  permitting operator adjustment of the Z-axis position of upper pole member  364  relative to middle pole member  363 . Lower pole member  354  receives and is selectably coupled with middle pole member  363  by set screws  368  permitting removal when desired. Lower pole member  354  is also slidably coupled with base member  352  and base member  352  is fixedly coupled with the chassis of work machine  101 . 
     In the illustrated form, the slidable coupling of lower pole member  354  and base member  352  is provided by lower pole member  354  being partially inserted into a central aperture of base member  352 . In other forms other types of slidable coupling between lower pole member  354  and base member  352  may be provided including, for example, base member  352  being partially inserted into a central aperture of lower pole member  354 , one or more portions of lower pole member  354  being provided in or configured to engage a groove or track provided in base member  352 , one or more portions of base member  352  being provided in or configured to engage a groove or track provided in lower pole member  354 , or one or more wheel or roller and corresponding one or more track members being provided in, to name several examples. The slidable coupling of lower pole member  354  with base member  352  permits lower pole member  354  to move up and down in the vertical or Z-axis direction while lower pole member  354  is at the same time fixed relative to the base member in the horizontal or X-axis and Y-axis directions. Thus, lower pole member  354  is permitted to move up and down relative to the base member  352  and the chassis in the vertical or Z-axis direction in response to force applied to lower pole member  354  by arm  356 , but is maintained at a fixed angle relative to the base member  352  and the chassis. 
     Receiver  192  is coupled with upper pole member  364  and is moveable relative to and can be fixed in place in a plurality of positions in the Z-axis direction along upper pole member  364 . The relative adjustability between various ones of upper pole member  364 , middle pole member  363 , lower pole member  354  and receiver  192  allows the receiver  192  to be positioned relative to a reference signal source such as a rotating laser. Preferably the receiver  192  can be adjusted to synch with a laser beam by loosening set screws  367 , adjusting upper pole member  364  relative to middle pole member  636 , and tightening set screws  367  once the desired synch has been achieved. As described in further detail above, receiver  192  and electronic controller  195  are configured to receive and to evaluate one or more reference signals, such as signals indicating a Z-axis elevation and an angle of a rotating laser beam detected by receiver  192 , and to determine actuator position adjustment commands based upon the received reference signal(s) and one or more operator-specified grading commands input to the electronic controller  195 . 
     In the automatic grading system of work machine  101 , base member  352 , pole assembly  350  and receiver  192  are positioned centrally in the X-axis direction along the chassis width or wheel track of work machine  101 . This central positioning reduces unintended variation in the operation of the automatic grading system that can arise under some operating conditions. For example, as work machine  101  travels back in forth in one direction laterally across a grade and then in the opposite direction laterally across the grade, the central positioning of base member  352 , pole assembly  350  and receiver  192  will reduce variation in Z-axis positioning of the receiver  192  that could otherwise occur. Preferably, the central positioning is in the center 40% of the chassis width or wheel track in the X-axis direction, i.e., within +/−20% of the chassis width or wheel track relative to a chassis centerline extending in the Y-axis direction which for many applications and operations provides acceptably similar operation and error mitigation as exact center positioning. More preferably, the central positioning is in the center 10% of the chassis width or wheel track in the X-axis direction, i.e., within +/−5% of the chassis width or wheel track relative to a chassis centerline extending in the Y-axis direction which for even more applications and operations provides substantially the same or acceptably similar operation and error mitigation as exact center positioning. Even more preferably still, the central positioning is in the center 10% of the chassis width or wheel track in the X-axis direction, i.e., within +/−5% of the chassis width or wheel track relative to a chassis centerline extending in the Y-axis direction which for most if not all applications and operations provides substantially the same operation and error mitigation as exact center positioning. 
     The automatic grading system of work machine  101  includes a sighting gauge  390  which is coupled with arm  356 . Sighting gauge  390  can be selectably positioned by an operator along the length of arm  356  by loosening set screw  392  and positioning sighting gauge  390  relative to arm  356 . After an operator achieves the desired positioning of sighting gauge  390 , set screw  392  can be tightened to fix the position of sighting gauge  390  relative to arm  356 . Sighting gauge  390  is provided with a scale providing an operator perceptible indication of relative positioning to a reference indicator  393  which is provided in a fixed relationship to the chassis of work machine  101 . Preferably the scale is structured to indicate a measurement of cut in a direction along the scale above the middle set point of the scale and a measurement of fill in a direction along the scale below the middle set point which may be differentiated by using contrasting colors such as red and green. Such a fixed relationship may be provided, for example, by providing reference indicator  393  on base member  352  as illustrated, or by providing a reference indicator another structure in a fixed relationship with the chassis of work machine and proximate to arm  356 . In some forms the reference indicator may be a surface  395  of the chassis and sighting gauge  390  may be positioned so that it is partially or completely below the surface  395 . The scale includes a center position indicator  390   c  which a center point of the scale. As rocker  124 , rotates, the Z-axis position of arm  356  and sighting gauge are varied thereby providing an operator perceptible indication of a grading set point. As illustrated in the view of  FIG. 12 , sighting gauge  390  may be provided in combination with sighting gauge system  202  which is described above. In other forms, only one of sighting gauge  390  and sighting gauge system  202  may be provided. 
     With reference to  FIGS. 15A-15E  there are illustrated schematic depictions of certain aspects of the automatic grading system of work machine  101  at a plurality of adjustment points over a range of adjustment. In the schematic depiction of  FIGS. 15A-15E , lifting connector  358  of rocker  124  is rotatably coupled with the chassis illustrated in  FIGS. 10-14  by pivotable coupling  408  at a point of rotation  359 , it being appreciated that certain elements have been omitted from the schematic depictions of  FIGS. 15A-15E  for clarity of illustration and that the geometry of lifting connector  358  has been simplified in the schematic views for clarity of illustration. Additionally, in the schematic depictions of  FIGS. 15A-15E , portions of pole assembly  350  extending above lower pole member  354  have been omitted for simplification and clarity of illustration. It shall nevertheless be appreciated that the elements of pole assembly  350  illustrated and described in connection with  FIGS. 10-14 and 16A-16E  are adjustably fixedly coupled with an extend above lower pole member  354  and move in a vertical or Z-axis direction in a substantially fixed relationship with lower pole member  354  over its range of motion in the vertical or Z-axis direction. 
     With continuing reference to  FIGS. 15A-15E  lifting connector  358  is rotatable relative to the chassis about a pivotable coupling at a point of rotation  359 . Lifting connector  358  is also rotatably coupled with arm  356  by pivotable coupling  355  and rocker  385  and arm  356  are rotatable relative to one another about a pivotable coupling at a point of rotation  355 . Arm  356  is also rotatably coupled with lower pole member  354  by pivotable coupling that is rotatable relative to lower pole member  354  about a third point of rotation  357 . Considering  FIGS. 15A-15E  in sequence, it can be seen that the first point of rotation provided by rotatably member  359  remains substantially fixed relative to the chassis as lifting connector  358  rotates while the second point of rotation provided by rotatably member  355  travels along a curved path. As a result of such rotation, a vertical or Z-axis direction force component is applied by arm  356  to lower pole member  354 . Through this mechanism, rotational motion of lifting connector  358  is translated into linear motion of lower pole member  354  in a vertical or Z-axis direction. Such translation may result in some amount of lost motion between the lifting connector  358  and the lower pole member  354 . The amount of lost motion at a minimum in the position illustrated in  FIG. 15B  when the arm is substantially aligned with the moveable member. 
     With reference to  FIG. 16A-16E  there are illustrated schematic depictions of certain aspects of work machine  101  and its example automatic grading system at a plurality of adjustment points over a range of adjustment. It shall be appreciated that the adjustment positions illustrated in  FIGS. 16A-16E  correspond generally to the adjustment positions in  FIGS. 15A-15E , respectively, although minor variations are present between the two sets of figures due to the schematic nature of  FIGS. 15A-15E . 
     In the adjustment position of  FIG. 16A , finishing box  170  and finishing comb  138  of the grading tool assembly coupled with tool mount  120  are in contact with and penetrate into the underlying ground surface  499 . Furthermore, the rotation of rocker  124  is such that the suspension  125  is compressed to a substantially maximum amount. In the adjustment position of  FIG. 16B , finishing box  170  and finishing comb  138  of the grading tool assembly coupled with tool mount  120  are also in contact with and penetrate into the underlying ground surface  499 . In this adjustment position however, the rotation of rocker  124  is such that the suspension  125  is compressed to a less than substantially maximum amount. 
     Considering adjustment positions of  FIGS. 16A and 16B  as example positions over a range of rotation of rocker  124 , it can be seen that rotation of the rocker  124  over such a range of rotation is effective to de-couple adjustment of the receiver  192  and the grading tool assembly and to vary the predetermined spacing relationship of the receiver  192  and the grading tool assembly due to compression of the suspension  125  with the grading tool assembly in contact with the underlying ground surface  499 . It shall be appreciated that such a range of rotation may include adjustment positions within bounds of the position of  FIGS. 16A and 16B  as well as positions outside these bounds up to positions at which compression of the suspension  125  occurs due to adjustment of the rocker  125 . 
     In the adjustment position of  FIG. 16C , the rotation of rocker  124  is such that finishing box  170  and finishing comb  138  of the grading tool assembly coupled with tool mount  120  are raised above the underlying ground surface  499  by a height HC in the Z-axis direction. In the adjustment position of  FIG. 16D , the rotation of rocker  124  is such that finishing box  170  and finishing comb  138  of the grading tool assembly coupled with tool mount  120  are raised above the underlying ground surface  499  by a height HD in the Z-axis direction. In the adjustment position of  FIG. 16E , the rotation of rocker  124  is such that finishing box  170  and finishing comb  138  of the grading tool assembly coupled with tool mount  120  are raised above the underlying ground surface  499  by a height HE in the Z-axis direction. In the adjustment positions of  FIGS. 16C-16E , the rotation of rocker  124  is such that the suspension  125  is compressed to a substantially minimum amount, which may be substantially zero compression or a non-zero preload of compression. Furthermore, in these adjustment positions the rotation of rocker  124  is such that chain  121  exerts a lifting force effective to maintain the grading tool assembly raised above the underlying ground surface  399 . 
     Considering the adjustment positions illustrated in  FIGS. 16C, 16D and 16E  as example positions over another range of rotation of rocker  124 , it can be seen that rotation of rocker  124  over a first range of rotation is effective to adjust the Z-axis position of the pole assembly  350  including receiver  192  and tool mount  120  including the grading tool assembly as a coupled pair with a predetermined spacing relationship of the receiver  192  and the grading tool assembly with the grading tool assembly spaced apart from an underlying ground surface  499 . It shall be appreciated that such a range of rotation may include intermediate adjustment positions within bounds of the position of  FIGS. 16C and 16E  in addition to the intermediate position  16 D and may also include positions outside these bounds up to positions at the suspension  125  is minimally compressed due to adjustment of the rocker  125 . 
     Work machines  100  and  101  and their respective automatic grading systems may be utilized in performing surveying operations to assess the amount of grade material that needs to be added or removed from various locations about a work site. In certain surveying operations, an operator may adjust the components of the automated grading system such that the grading tool assembly is raised above the underlying ground surface when the receiver is in a target grade position (e.g., a desired elevation and/or angle) and the grading tool assembly remains raised above the underlying ground surface over a range of motion in the Z-axis direction corresponding to the range of adjustment of the receiver in the Z-axis detection by electronic controller. This positioning may be selected to account for estimated variation in the underlying ground surface for a given worksite. An operator may further position one or more sighting gauge components to provide an operator perceptible indication of movement above and below the target grade position, for example, by setting the relationship between center position indicator  390   c  and reference indicator  393 . 
     By way of example, an operator may conduct a survey operation by configuring and operating work machine  100  or work machine  101  as follows. The operator may manipulate the Z-axis position of the grading tool assembly such that it is raised above the underlying ground surface to an expected neutral point. For example, a neutral point may be selected by positioning the work machine at a position believed to be close to a target grade and adjusting the Z-axis position to be at a predetermined position between the underlying ground surface and its maximum upper Z-axis position. 
     If the work site is estimated to have fill and cut regions with generally the same magnitude of variation from a target grade, the predetermined position may be selected at a midpoint position between the underlying ground surface and the maximum upper Z-axis position of the grading tool assembly. The predetermined position may also be selected to be higher or lower than the midpoint position if a worksite is estimated to have cut regions with a greater magnitude of variation from a target grade than its fill regions or to have fill regions with a greater magnitude of variation from a target grade than its cut regions. 
     In the grading system of work machine  101 , the expected neutral point may additionally or alternatively be selected such that the arm  356  is substantially parallel to the Z-axis direction or substantially aligned with base member  352 . Such positioning may be selected to minimize a Z-axis lost motion effect exhibited by arm  356  at the neutral point due to the translation of rotational motion of rocker  124  to Z-linear motion of pole assembly  350 . 
     With the Z-axis position of the grading tool assembly established, the operator may then adjust the Z-axis position of receiver  192  to be substantially at the midpoint of its detection range in the Z-axis direction relative to a wireless reference signal such as a laser beam. This adjustment may be performed by adjusting the position of the receiver  192  relative to positioning pole  194  or pole assembly  350 , by adjusting the relative positioning between one or more of the upper pole member  364 , middle pole member  363  and a lower pole member  354  to vary the length of the pole assembly  350  or by various combinations of such adjustments. 
     With the Z-axis position of the grading tool assembly and the Z-axis position of the receiver  192  established, the operator may adjust position of a sighting gauge component to provide an operator perceptible indication that the receiver is at the target grade. Sighting gauge  390  may be adjusted relative to arm  356  such that scale providing an operator perceptible indication of target grade positing relative to reference indicator  393  for example, by aligning center position indicator  390   c  with reference indicator  393 . Sighting gauge system  202  may be adjusted to indicate a degree of compression of the suspension spring by aligning the top of inner member  206  or  306  with the top of outer member  204  or  304  to indicate a zero compression state of the suspension spring and indicating an amount of cut to achieve a desired grade through the extension of inner member  206  or  306  with the top of outer member  204  or  304  corresponding to the degree of compression of the suspension spring. 
     With the Z-axis position of the grading tool assembly, the Z-axis position of the receiver  192  and the sighting gauge position established, the operator may pilot the work machine around the work area and observe and notate the grade information indicated by the sighting gauge. For example, the volume of a fill region may be estimated by observing the fill depth indicated by the sighting gauge over a known or determined area of travel. Similarly, the volume of a cut region may be estimated by observing the cut depth indicated by the sighting gauge over a known or determined area of travel. Furthermore, the filling and grading regions for a given area can be substantially fully determined or mapped by piloting the work machine over the work area and observing and notating the cut or fill depths of the sighting gauge. Through use of such techniques an operator can rapidly survey a work area and estimate a volume of fill needed for the worksite and/or a volume of cut available for use at the worksite or which may require transport away from the worksite. 
     With reference to  FIGS. 17-24 , there are illustrated several views depicting certain aspects of an example work machine  101 ′ operatively coupled with an example automatic grading system. Work machine  101 ′ and its example automatic grading system include a number of features that are the same as or similar to the features described above in connection with work machine  101 , work machine  100 , and their respective automatic grading systems. A number of such features are indicated with like reference numerals and the description of such features in connection with work machine  101  or work machine  100  shall be understood to apply, mutatis mutandis, to the work machine  101 ′. While some such features are labeled with like reference numerals or otherwise illustrated in the drawings, it shall be appreciated that other aspects, alternatives, and variations described or illustrated in connection with work machine  101 , work machine  100 , and their respective automatic grading systems, is also applicable to at least some forms and embodiments of work machine  101 ′ unless expressly or impliedly indicated to the contrary. 
     Work machine  101 ′ and its example automatic grading system also include certain aspects which differ or vary from those of work machine  101 , work machine  100 , and their respective automatic grading systems, a number of which are illustrated in connection with  FIGS. 17-24 . In one such aspect, the automatic grading system of work machine  101 ′ comprises multiple actuators which are operatively coupled to respective suspension elements, are configured and operable to be automatically controlled, independently or in combination, in response to control signals from electronic controller  495 , and are configured and operable to be manually controlled, independently or in combination, in response to control signals from operator controls  150 ′. 
     In the illustrated embodiment, the electronic controller  495  is in operative communication with a first actuator  440   a , a second actuator  440   b , and a receiver  492 . The receiver  492  is operable to receive a wireless signal including positional information, also referred to as a positional information signal, and to provide the positional information signal or positional information thereof to electronic controller  495 . The positional information signal may be provided in a number of forms interpretable by the electronic controller to determine or judge a position of the work machine. The positional information signal may comprise a global navigation satellite system (GNSS) signal, for example, a global positioning system (GPS) signal, a Galileo system signal, or other signals from other global or regional satellite systems or sources. The positional information signal may additionally or alternatively comprise a local positioning system (LPS) signal. A number of LPS may be utilized to provide such signals including indoor or in-structure systems and worksite systems. In some embodiments, an LPS signal may be provided by a total station (TS) or total station theodolite (TST) system. Such TS or TST systems comprising electronic and/or optical instrumentation which may comprise an electronic transit theodolite integrated with electronic distance measurement (EDM) to measure both vertical and horizontal angles and the slope distance from the instrument to a particular point, and an on-board computer to collect data and perform triangulation calculations. 
     In response to the positional information signal, the electronic controller  495  is configured and operable to automatically control the first actuator  440   a  and the second actuator  440   b , independently or in combination or coordination with one another. The operator controls  150 ′ are also in operative communication with the first actuator  440   a  and the second actuator  440   b  and can provide control signals in response to operator input to manually control the first actuator  440   a  and the second actuator  440   b , independently or in combination or coordination with one another. 
     The first actuator  440   a  is operatively coupled with a first rocker  424   a  at a pivotable coupling  506   a . The first rocker  424   a  is further operatively coupled with the chassis at a pivotable coupling  508   a . The first actuator  440   a  is also coupled with the chassis of the work machine  101 ′ at a pivotable coupling and is controllable by the electronic controller  495  and by the operator controls  150 ′ to selectably expand and contract generally in the Y-axis direction effective to cause the first rocker  424   a  to rotate relative to the chassis at the pivotal coupling  508   a  about an axis generally parallel with the X-axis direction. The first rocker  424   a  includes a first outer arm member  502   a  which is coupled with a first suspension element  125   a . The first rocker  424   a  also includes a first shaft member  504   a  which extends between and is coupled with the first outer arm member  502   a  and the first pivotable coupling  508   a . The first rocker  424   a  further includes a first inner arm member  503   a  which is coupled with and extends between the pivotable coupling  506   a  and the pivotable coupling  508   a . The first rocker  424   a  includes a first lifting arm member which is coupled with the first shaft member  504   a  and a first portion of the flexible rigging  421  which comprises a chain in the illustrated embodiment and may comprise a cable or other flexible rigging members in other embodiments. 
     Rotation of the first rocker  424   a  over a first range of motion is effective to raise or lower at least a first portion of the tool mount  120  in the Z-axis direction. In some forms, the first portion of the tool mount  120  comprises at least the first side (e.g., X-axis direction end or extremity) of the tool mount  120 . In some forms, the first portion of the tool mount  120  comprises at least a first widthwise portion of the tool mount  120  extending intermediate the first side of the tool mount  120  and position at which the tool mount  120  is coupled with the flexible rigging  421 . In some forms, the first portion of the tool mount  120  comprises at least a second widthwise portion of the tool mount  120  extending intermediate the first side of the tool mount  120  and position at which the tool mount  120  is coupled with the second suspension element  125   b . The raising and lowering can be effectuated or provided by a lifting connection provided between the first lifting arm member, a first portion of the flexible rigging  421 , and the tool mount  120 , and can occur over a first predetermined range between a maximum height and a ground-contacting point at which the tool mount  120  or a tool coupled therewith contacts an underlying ground surface in a manner which limit further lowering or downward or Z-axis motion of the tool mount  120  and a tool coupled thereto. 
     From the ground contacting point, further rotation of the first rocker  424   a  may be performed over a second range of motion to compress or decompress the first spring  126   a  or other compressible suspension component(s) of the first suspension element  125   a  from the ground contacting point to a maximum compression point. Thus, rotation of the first rocker  424   a  may be performed to vary the amount of shock absorption force applied to the tool mount  120  by varying the compression of the first spring  126   a  without substantially changing the Z-axis position of at least the first portion of the tool mount  120 . Depending on the degree of compression of the first spring  126   a , the first suspension element  125   a  can also accommodate movement of the tool mount  120  in response to external force applied thereto, for example, if the tool mount  120  contacts an obstruction such as a rock or other structure located in a soil medium being worked. 
     The second actuator  440   b  is operatively coupled with a second rocker  424   b  at a pivotable coupling  506   b . The second rocker  424   b  is further operatively coupled with the chassis at the pivotable coupling  508   b . The second actuator  440   b  is also coupled with the chassis of the work machine  101 ′ at a pivotable coupling and is by the electronic controller  495  ant the operator controls  150 ′ to selectably expand and contract generally in the Y-axis direction effective to cause the second rocker  424   b  to rotate relative to the chassis at the pivotal coupling  508   b  about an axis generally parallel with the X-axis direction. The second rocker  424   b  includes a second outer arm member  502   b  which is coupled with a second suspension element  125   b . The second rocker  424   b  also includes a second shaft member  504   b  which extends between and is coupled with the second outer arm member  502   b  and the second pivotable coupling  508   b . The second rocker  424   b  further includes a second inner arm member  503   b  which is coupled with and extends between the pivotable coupling  506   b  and the pivotable coupling  508   b . The second rocker  424   b  includes a second lifting arm member which is coupled with the second shaft member  504   b  and a second distal portion of the flexible rigging  421 . 
     Rotation of the second rocker  424   b  over a first range of motion is effective to raise or lower at least a second portion of the tool mount  120  in the Z-axis direction. In some forms, the second portion of the tool mount  120  comprises at least the second side (e.g., X-axis direction end or extremity) of the tool mount  120 . In some forms, the second portion of the tool mount  120  comprises at least a first widthwise portion of the tool mount  120  extending intermediate the second side of the tool mount  120  and position at which the tool mount  120  is coupled with the flexible rigging  421 . In some forms, the second portion of the tool mount  120  comprises at least a second widthwise portion of the tool mount  120  extending intermediate the second side of the tool mount  120  and position at which the tool mount  120  is coupled with the first suspension element  125   a . The raising and lowering can be effectuated or provided by a lifting connection provided between the second lifting arm member, a second portion of the flexible rigging  421 , and the tool mount  120 , and can occur over a second predetermined range between a maximum height and a ground-contacting point at which the tool mount  120  or a tool coupled therewith contacts an underlying ground surface in a manner which limit further lowering or downward or Z-axis motion of the tool mount  120  and a tool coupled thereto. 
     From the ground contacting point, further rotation of the second rocker  424   b  may be performed over a second range of motion to compress or decompress the second spring  126   b  or other compressible suspension component(s) of the second suspension element  125   b  from the ground contacting point to a maximum compression point. Thus, rotation of the second rocker  424   b  may be performed to vary the amount of shock absorption force applied to the tool mount  120  by varying the compression of the second spring  126   b  without substantially changing the Z-axis position of at least the first portion of the tool mount  120 . Depending on the degree of compression of the second spring  126   b , the second suspension element  125   b  can also accommodate movement of the tool mount  120  in response to external force applied thereto, for example, if the tool mount  120  contacts an obstruction such as a rock or other structure located in a soil medium being worked. 
     The first actuator  404   a  and the second actuator  440   b  may be controlled concurrently or sequentially to equivalent adjustment positions to emulate the operation of a single actuator such as actuator  140  of work machine  100  or work machine  101 .  FIGS. 17, 19 , and  21  illustrate such a state of adjustment wherein the tool mount  120  is flat or biased toward the same Z-axis position over its width extending in the X-axis direction and any tools coupled with the tool mount  120  are similarly biased or positioned. In other such states of adjustment, the tool mount  120  may be flat or biased toward other common Z-axis positions with the tool mount  120  and one or more tools as may be coupled therewith provided at or biased toward a different Z-axis position above or below the position illustrated in  FIGS. 17, 19, and 21 . 
     The first actuator  404   a  and the second actuator  440   b  may be controlled concurrently or sequentially to different adjustment positions to provide lateral tilting (also referred to as side-to-side or widthwise tilting) of the tool mount  120  and one or more tools as may be coupled therewith.  FIGS. 18, 20, 22, 23, and 24  illustrate such as state of adjustment wherein the tool mount  120  is provided at or biased toward different Z-axis position along its width and any tools coupled with the tool mount  120  are similarly biased or positioned. Furthermore, in such states of adjustment, the first spring  126   a  and the second spring  126   b  are compressible either separately and independently or in combination but to different degrees to vary the side-to-side or widthwise tilt of the tool mount  120  without adjustment of the first actuator and without adjustment of the second actuator. 
     In other such states of adjustment, the tool mount  120  may be laterally tilted or biased toward different Z-axis positions which are respectively above or below the position illustrated in  FIGS. 18, 20, 22, 23, and 24 , and may be laterally tilted at different angles greater or lesser than the illustrated lateral tilt angles ranging from a first maximum tilt position wherein a first lateral end of the tool mount is at a maximum Z-axis position and a second lateral end of the tool mount is at a minimum Z-axis position to a second maximum tilt position wherein the first lateral end of the tool mount is at a minimum Z-axis position and a second lateral end of the tool mount is at a maximum Z-axis position. Furthermore, in such states of adjustment, the first spring  126   a  and the second spring  126   b  are compressible either separately and independently or in combination but to different degrees to vary the side-to-side or widthwise tilt of the tool mount  120  without adjustment of the first actuator and without adjustment of the second actuator. 
     In the illustrated embodiment, the flexible rigging  421  is coupled with the tool mount  120  at a single connection point and can slide or otherwise move along its length relative to the single connection point in response to adjustment of the first rocker  424   a  and the second rocker  424   b . For example, if the first rocker  424   a  is raised and the second rocker  424   b  is lowered, the flexible rigging  421  can slide relative to its coupling location with the tool mount  120  to increase the length of the portion of flexible rigging  421  coupled with the first rocker  424   a , decrease the length of the portion of flexible rigging  421  coupled with the second rocker  424   b , and depending on the net effect of the adjustments, maintain, increase, or decrease the Z-axis positioning of the tool mount  120 . The flexible rigging  421  can thereby provide a net effective length or Z-axis positioning of the tool mount  120  which is an average or weighted and/or offset average of the length or Z-axis positioning that would otherwise be provided by the respective adjustment positions of the first rocker  424   a  and the second rocker  424   b.    
     In other embodiment, the flexible rigging  421  may be coupled with the tool mount  120  at two connection points spaced apart laterally along the width of the tool mount  120  in the X-axis direction such that the flexible rigging  421  can slide or otherwise move along its length relative to the two connection points in response to adjustment of the first rocker  424   a  and the second rocker  424   b . For example, if the first rocker  424   a  is raised and the second rocker  424   b  is lowered, the flexible rigging  421  can slide relative to its coupling locations with the tool mount to increase the length of the portion of flexible rigging  421  coupled with the first rocker  424   a , decrease the length of the portion of flexible rigging  421  coupled with the second rocker  424   b , and depending on the net effect of the adjustments, maintain, increase, or decrease the Z-axis positioning of the tool mount  120 . The flexible rigging  421  can thereby provide a net effective length or Z-axis positioning of the tool mount  120  which is an average or weighted and/or offset average of the length or Z-axis positioning that would otherwise be provided by the respective adjustment positions of the first rocker  424   a  and the second rocker  424   b.    
     In other embodiments, the flexible rigging  421  may be coupled with the tool mount  120  at a single connection point such that the flexible rigging  421  is fixed and does not slide or move along its effective length in response to adjustment of the first rocker  424   a  and the second rocker  424   b . The flexible rigging  421  can thereby provide a net effective length or Z-axis positioning of the tool mount  120  which is the lesser of the length or Z-axis positioning provided by the respective adjustment positions of the first rocker  424   a  and the second rocker  424   b.    
     In other embodiment, the flexible rigging  421  may be coupled with the tool mount  120  at two connection points spaced apart along the width of the tool mount  120  in the X-axis direction such that the flexible rigging  421  is fixed and does not slide or move along its effective length in response to adjustment of the first rocker  424   a  and the second rocker  424   b . The flexible rigging member can thereby provide a net effective length or Z-axis positioning of the tool mount  120  which is the lesser of the length or Z-axis positioning provided by the respective adjustment positions of the first rocker  424   a  and the second rocker  424   b.    
     In other embodiment, the flexible rigging  421  may comprise two separate portions respectively coupled with the tool mount  120  at a common connection point or at two connection points spaced apart along the width of the tool mount  120  in the X-axis direction such that two separate portions of flexible rigging  421  are fixed and do not slide in response to adjustment of the first rocker  424   a  and the second rocker  424   b  to provide a net effective length or Z-axis positioning of the tool mount  120  which is the lesser of the length or Z-axis positioning provided by the respective adjustment positions of the first rocker  424   a  and the second rocker  424   b.    
     Actuator  142  is selectably controllable to expand and contract generally in the Y-axis direction effective to cause tool mount  120  to rotate relative to the work machine about an axis generally parallel with the X-axis direction. In this manner, the pitch of the tool mount X-Y plane may be varied. This rotation can be utilized to rotate the grading tool assembly  120  (raising one of the forward edge and the rearward edge and lowering the other) relative to the underlying ground surface and to control the force it applies to the underlying ground surface in the Z-axis direction. Tool mount  120  is coupled with the first suspension element  125   a  by a first pivotable coupling and is coupled with the second suspension element  125   b  by a second pivotable coupling. The first suspension element  125   a  and the second suspension element  125   b  are respectively connected to the first rocker  424   a  and the second rocker  424   b  at respective pivotable couplings. Tool mount  120  is further coupled with a pulling linkage  130  at a pivotable coupling which rotates generally about an axis in parallel with the X-axis direction. Pulling linkage  130  is coupled with the chassis of the work machine at a pivotable coupling which rotates about an axis in parallel with the X-axis direction. Pulling linkage is configured to provide a force vector component to the tool assembly in the forward or reverse Y-axis direction as the machine is propelled forward or backward. A force vector component generally in the Y-axis direction may also be provided, for example, during turning of the machine. Regardless of the particular direction, the pulling linkage provides one or more force vector components providing working force to the tool assembly. Furthermore, the rotation permitted by pivotable couplings between pulling linkage and the chassis of the work machine accommodates both adjustment of the height or Z-axis potion, front-to-back or lengthwise angle or pitch of the tool assembly relative to the X-Y plane, and side-to-side or widthwise angle or pitch of the tool assembly relative to the X-Y plane. 
     The automatic grading system of work machine  101 ′ includes a pole assembly  550  with which the receiver  492  is coupled. In other embodiments, the receiver  492  may be coupled with other components or provided at other locations of the work machine  101 ′. The pole assembly  550  includes an upper pole member  564 , a middle pole member  563 , and a lower pole member  554 . Upper pole member  564  receives and is adjustably coupled with middle pole member  563  by set screws or other fasteners permitting operator adjustment of the Z-axis position of upper pole member  564  relative to middle pole member  563 . Lower pole member  554  receives and is selectably coupled with middle pole member  563  by set screws or other fasteners permitting removal when desired. In some embodiments, the lower pole member  554  may be slidably coupled with a base member fixedly coupled with the chassis of work machine  101 ′. In some embodiments, the lower pole member  554  may be fixedly coupled with a base member fixedly coupled with the chassis of work machine  101 ′. 
     In some forms, the receiver  492  may comprise one or more global navigation satellite system (GNSS) receivers, for example, one or more global positioning system (GPS) receivers or other types of GNNS receivers, which may be configured and operable to receive a positional information signal from a satellite-based transmission source, a terrestrial-based repeater or relay source, or another positional signal generation source. The GNNS receiver may be of a number of types including, for example, as a dual-frequency GNNS receiver or another type of GNNS receiver. In some forms, the receiver  492  may additionally or alternatively comprise a local positioning system (LPS) receiver, for example, a total station (TS) or total station theodolite (TST) receiver or other types of LPS receivers, which may be configured and operable to receive a positional information signal from a transmission source provided at a worksite or other location of interest. The receiver  492  may detect, demodulate, decode, or otherwise process received positional information signals and provide the detected, demodulated, decoded, or otherwise processed positional information signals or positional information thereof to electronic controller  495 . The electronic controller  495  may adjust one or both of the first actuator  440   a  and the second actuator  440   b  in response to the positional information signals. 
     In some forms, the electronic controller  495  may be configured with a grading map, for example, a multi-dimensional array, matrix, other data structure comprising a plurality of map position and a corresponding or correlated plurality of adjustment commands or settings for the first actuator  440   a  and for the second actuator  440   b . The grading map may be stored in one or more non-transitory memory devices of the electronic controller  495  (e.g., provided in or operatively coupled with the electronic controller  495 ). The electronic controller  495  is configured and operable to process the positional information from the receiver  492  to identify a matching (or best or most closely matching) one of the plurality of map positions, determine or identify a corresponding adjustment command or setting of the first actuator  440   a  and a corresponding adjustment command or setting of the second actuator  440   b , and, in response thereto, generate and output control signals to control the first actuator  440   a  to a position or adjustment state according to its respective determined or identified adjustment command or setting, and to control the second actuator  440   b  to a position or adjustments according to its respective determined or identified adjustment command or setting. The plurality of adjustment commands or settings and/or the positions or adjustment states of the first actuator  440   a  and the second actuator  440   b  may be selected to bias the tool mount  120  to predetermined Z-axis positions and predetermined side-to-side, or widthwise tilting at each of a plurality of locations of the grading map. 
     In one example, the grading map comprises a plurality of map positions corresponding to locations in the area of a given worksite and preferably substantially covering an area of the worksite which is to be automatically graded. Each of the plurality of map positions corresponds to or is correlated with, directly or indirectly via one or more intermediate links, calculations, or other operations, an adjustment command or setting for the first actuator  440   a  and an adjustment command or setting for the second actuator  440   b . For example, the adjustment commands or settings for the first actuator  440   a  and the second actuator  440   b  may correspond to grading parameters including a Z-axis grade depth, X-axis pitches or angles relative to the X-Y plane, and Y-axis pitches or angles relative to the X-Y plane for each of the map positions. The controller  495  is further configured to automatically adjust the first actuator  440   a  and the second actuator  440   b  to bias the first suspension element  125   a , the second suspension element  125   b , and the tool mount  120  and any tools coupled thereto toward the corresponding grading parameters for each of the map positions. The controller  459  may also be configured to transition between map positions by averaging or interpolating between grading parameters for adjacent or contiguous map positions. 
     The work machine  101 ′ can be operated to travel over and automatically grade the area of the worksite covered by the grading map. During such operation, the tool mount  120  and any tools coupled thereto are biased toward a position providing the grading parameters defined by the grading map. The first suspension element  125   a  and the second suspension element  125   b  may compress in response to force generated by contact with the underlying ground surface causing the tool mount  120  and any tools attached thereto to move be displaced from their biased positions. The work machine  101 ′ may make repeated passes as needed to eliminate such displacement achieve the grading parameters defined by the grading map. 
     The receiver  492  may be provided in a number of forms, including those described above, and may also be provided in a number of positions relative to various structures of the work machine. For example, various forms of the receiver may comprise a GNNS receiver, an LPS, receiver a laser receiver, or a combination of two or more such receivers. 
     In some embodiments, the pole assembly  550  and the receiver  492  are maintained at a substantially fixed position relative to the chassis of the work machine  101 ′ and the receiver  492  may comprise a GNNS receiver or an LPS receiver. In other embodiments, the pole assembly  550  and the receiver  492  may be moveable or adjustable to a plurality of Z-axis positions relative to the chassis of the work machine  101 ′ in response to operation of the first actuator  440   a  or the second actuator  440   b  and the receiver  492  may comprise a combination of a GNNS receiver or an LPS receiver and a laser receiver such laser receiver  192 . In such forms, the pole assembly  550  be operatively coupled with one of the first rocker  424   a  and the second rocker  424   b  using a mechanism substantially similar to that illustrated and described in connection with the work machine  101 , including the features illustrated and described in connection with  FIGS. 15A-15E  and  FIGS. 16A-16E  but coupled with and moveable with only one of the first rocker  424   a  or its associated structures and the second rocker  424   b  or its associated structures. 
     Some embodiments may comprise one or more GNNS receivers or LPS receivers and one or more separate laser receiver. In some such embodiments, the receiver  492  may be a GNNS receiver or an LPS receiver provided on the assembly  550  which is maintained at a substantially fixed position relative to the chassis of the work machine  101 ′ and a second receiver  192 ′ may be provided on a separate pole coupled with one of the first suspension element  125   a  and the second suspension element  125   b  and which may be the same as or substantially similar to the receiver  192  and the pole  194  illustrated and described in connection with the work machine  101 . In some such embodiments, the receiver  492  may be a laser receiver provided on the pole assembly  550  which may be moveable to a plurality of Z-axis positions relative to the chassis of the work machine  101 ′ and a second, separate GNNS receiver or an LPS receiver may be separately provided, for example, on a separate location fixedly coupled with the chassis of the work machine  101  such as on a separate fixed position pole. 
     The work machine  101 ′ may include one or more of the sighting gauge features described in connection with work machine  101  and work machine  100 , including the sighting gauge system  202 , the sighting gauge  390 , or both the sighting gauge system  202  and the sighting gauge  390 . Furthermore, as illustrated in  FIG. 23 , multiple sighting gauges  202   a ,  202   b  may be provided in combination with the first suspension element  125   a  and the second suspension element  125   b , respectively to provide independent visual indicia of the position of each side of the tool mount  120  and one or more tools as may be coupled therewith. 
     Some forms of the automatic grading system of the work machine  101 ′ may comprise one or more additional receivers configured and operable to provide information indicative of a lateral tilt (also referred to as side-to-side or widthwise tilt) of one or more components of the automatic grading system and/or the work machine  101 ′. Several examples of such forms are illustrated and described in connection with  FIGS. 25A, 25B, and 25C , and  FIGS. 26A, 26B, and 26C . 
     With reference to  FIGS. 25A, 25B, and 25C , there are illustrated certain portions of the automatic grading system of work machine  101 ′ which are depicted in isolation from other portions for clarity of illustration. It shall be appreciated that the illustrated aspects of  FIGS. 25A, 25B, and 25C  may be provided in connection with any of the embodiment, forms, modifications, and variants of the work machine  101 ′ and the automatic grading system thereof disclosed herein. 
     The automatic grading system of work machine  101 ′ may comprise a tilt sensor system  570  including one or more provided on a linkage  574  which is operatively coupled with the first suspension element  125   a  at a first pivotable coupling  572   a  and is operatively coupled with the second suspension element  126   b  at a second pivotable coupling  572   b . In the embodiment or form of  FIGS. 25A, 25B, and 25C , the tilt sensor system  570  is coupled with the first suspension element  125   a  and the second suspension element  125   b  at respective locations positioned above or on a first side of the springs  126   a  and  126   b , respectively. Additionally or alternatively, one more sensors may be coupled with the first suspension element  125   a  and the second suspension element  125   b  at other locations above or on the first side of the springs  126   a  and  126   b . The one or more tilt sensors  579  are in operative communication with the electronic controller  495  and the one or more tilt sensors  579  and the electronic controller  495  are in combination configured to determine a lateral tilt (also referred to as side-to-side or widthwise tilt) of the tool mount  120  and one or more tools as may be coupled therewith. 
     As illustrated in  FIG. 25A , the first actuator  404   a  and the second actuator  440   b  may be adjusted to substantially the same position such that springs  126   a  and  126   b  have substantially the same degree of compression. In such states, the one or more tilt sensors  579  are positioned by linkage  572  to have substantially zero lateral tilt and will sense and provide to the electronic controller  495  a signal indicative of this tilt. In this state of adjustment, the signal indicative substantially zero lateral tilt also corresponds to the lateral tilt of the tool mount  120  and one or more tools as may be coupled therewith. 
     As illustrated in  FIG. 25B , the first actuator  404   a  and the second actuator  440   b  may be adjusted to different positions such that springs  126   a  and  126   b  have different degrees of compression, for example, due to greater compression of one of the springs  126   a  and  126   b  via contact with an underling ground surface GS. In such states, the one or more tilt sensors  579  are positioned by linkage  574  to have a non-zero lateral tilt and will sense and provide to the electronic controller  495  a signal indicative of this tilt. In this state of adjustment, the signal indicative lateral tilt does not correspond to the actual lateral tilt of the tool mount  120  and one or more tools as may be coupled therewith, but does correspond to the angle or degree of tilt to which the tool mount  120  and one or more tools as may be coupled therewith are biased and may ultimately achieve once the underlying ground surface GS is worked to accommodate such positioning. 
     Decoupling of the angle or degree of lateral tilt sensed by the one or more tilt sensors  579  and the actual to the angle or degree of tilt of the tool mount  120  and one or more tools as may be coupled therewith permits the automatic grading system to follow the adjustment commands determined by the electronic controller  495  in response to received positional information even when the corresponding grade cannot be immediately achieved. This capability amplifies the effectiveness of the work machine  101 ′ allowing grading to be achieved that would otherwise require heavier equipment or greater force. Thus, from the state of adjustment of  FIG. 25B , grading operation of the work machine  101 ′ may continue until the signal indicative lateral tilt corresponds to the actual lateral tilt of the tool mount  120  and one or more tools as may be coupled therewith and the desired grading of the underlying ground surface GS has been achieved. Such a state of adjustment is illustrated, for example, in  FIG. 25C . 
     With reference to  FIGS. 26A, 26B, and 26C , there are illustrated certain portions of the automatic grading system of work machine  101 ′ which are depicted in isolation from other portions for clarity of illustration. It shall be appreciated that the illustrated aspects of  FIGS. 25A, 25B, and 25C  may be provided in connection with any of the embodiment, forms, modifications, and variants of the work machine  101 ′ and the grading system thereof disclosed herein. 
     The automatic grading system of work machine  101 ′ may comprise a tilt sensor system  570 ′ including one or more tilt sensors  579 ′ provided on a linkage  574 ′ which is operatively coupled with the first suspension element  125   a  at a first pivotable coupling  572   a ′, and is operatively coupled with the second suspension element  126   b  b at a second pivotable coupling  572   b ′. In the embodiment or form of  FIGS. 26A, 26B, and 26C , the tilt sensor system  570 ′ is coupled with the first suspension element  125   a  and the second suspension element  125   b  at respective locations positioned below or on a second side of the springs  126   a  and  126   b , respectively. Additionally or alternatively, one more sensors may be provided at other locations below or on the second side of the springs  126   a  and  126   b , for example, on the tool mount  120  as one or more tilt sensors  579 ″. The one or more tilt sensors  579 ′ are in operative communication with the electronic controller  495  and the one or more tilt sensors  579 ′ and the electronic controller  495  are in combination configured to determine a lateral tilt (also referred to as side-to-side or widthwise tilt) of the tool mount  120  and one or more tools as may be coupled therewith. 
     As illustrated in  FIG. 26A , the first actuator  404   a  and the second actuator  440   b  may be adjusted to substantially the same position such that springs  126   a  and  126   b  have substantially the same degree of compression. In such states, the one or more tilt sensors  579 ′ are positioned by linkage  574 ′ to have substantially zero lateral tilt and will sense and provide to the electronic controller  495  a signal indicative of this tilt. In this state of adjustment, the signal indicative substantially zero lateral tilt also corresponds to the lateral tilt of the tool mount  120  and one or more tools as may be coupled therewith. 
     As illustrated in  FIG. 26B , the first actuator  404   a  and the second actuator  440   b  may be adjusted to different positions such that springs  126   a  and  126   b  have different degrees of compression, for example, due to greater compression of one of the springs  126   a  and  126   b  via contact with an underling ground surface GS. In such states, the one or more tilt sensors  579 ′ are positioned by linkage  572  to have substantially zero lateral tilt and would sense and provide to the electronic controller  495  a signal indicative of this tilt if the compression one or both of the springs  126   a  and  126   b  is not accounted for. 
     Additional sensors may be provided to account for or correct for differences in relative compression or deflection or compression of one or both of the springs  126   a  and  126   b . A sensor  177   a  may be operatively coupled with the first suspension element  125   a  and configured and operable to sense the degree or magnitude of compression or deflection of the spring  126   a . A sensor  177   b  may be operatively coupled with the second suspension element  125   b  and configured and operable to sense the degree or magnitude of compression or deflection of the spring  126   b . The sensor  177   a  and the sensor  177   b  may be in operative communication with the electronic controller  495  and in combination therewith may be utilized to adjust a signal otherwise indication substantially zero tilt to an adjusted signal indicating the angle or degree of tilt to which the tool mount  120  and one or more tools as may be coupled therewith are biased and may ultimately achieve once the underlying ground surface GS is worked to accommodate such positioning. 
     Decoupling of the adjusted angle or degree of lateral tilt (which is determined from the information sensed by the one or more tilt sensors  579  and the sensor  177   a  and the sensor  177   b ) and the actual to the angle or degree of tilt of the tool mount  120  and one or more tools as may be coupled therewith permits the automatic grading system to follow the adjustment commands determined by the electronic controller  495  in response to received positional information even when the corresponding grade cannot be immediately achieved. This capability amplifies the effectiveness of the work machine  101 ′ allowing grading to be achieved that would otherwise require heavier equipment or greater force. Thus, from the state of adjustment of  FIG. 26B , grading operation of the work machine  101 ′ may continue until the signal indicative lateral tilt corresponds to the actual lateral tilt of the tool mount  120  and one or more tools as may be coupled therewith and the desired grading of the underlying ground surface GS has been achieved. Such a state of adjustment is illustrated, for example, in  FIG. 26C . 
     While example embodiments have been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain example embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicates that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. Language indicating spatial or geometric relationships, directions or characteristic shall be understood to include and encompass relationships that are within a margin of variation which a person of skill in the art would deem acceptable for a given application.