The present invention generally relates to earth moving equipment, and more particularly to a grading system for use on a vehicle.
Earth moving equipment is available in different forms and for different purposes. Once excavation and concrete contractors have completed major work, which may include excavating and/or pouring a foundation for a structure, such as a commercial building or house, a dirt contractor works to build up or cut down the dirt pad or ground on the site, which may include the area around and inside of a structure. The dirt contractor is tasked with bringing the site to within 1/10 of a foot of the specifications on a grading site plan. Following the work by a dirt contractor, a fine grading contractor is brought in to move dirt and/or gravel with a goal in fine grading to achieve the highest quality slab and to keep the waste factor as little as possible. With known grading systems, this effort often results in finishing within ⅜″ or ½″ of the grading site plan.
It would be particularly advantageous to be able to use an automated grade control system on a fine grader, but typical skid steer vehicles and grading blade assemblies used for fine grading are not equipped to sufficiently control a blade to permit accurate automated control. There are some specialized grading systems that are capable of employing automation, but the structures unfortunately have undesirable bounce or instability of the grading system and little downward pressure, which results in very limited ground cutting ability and ultimately limits the ability to achieve the intended goal in fine grading. The limitations can be due to the extent to which a grading system extends forward from the vehicle, the use of forward support wheels and/or the mounting and controls, which typically include vertically movable arms on the vehicle and hydraulic actuators to control the pitch of a quick attach mounting plate.
It is common for a blade of a grading system to sit level with the tracks of a vehicle on a ground surface when the vertically movable arms of the vehicle are moved to a lowermost position against stops. However, in fine grading, it may be necessary to cut into the ground with a blade, such as when attempting to reduce the elevation of a surface, or to otherwise lower a blade when moving a pile of soil. To do so, the known vehicles that have a level blade with the vertically movable arms of a vehicle against a lower stop must use a pitch control on the vehicle to tilt the quick attach mounting plate forward so as to extend the lower edge of the grading blade below the height of the vehicle tracks, however, this causes the pivot axis of the grading blade to be significantly tilted, interfering with the ability to use a grading control system. There have been developments that include adding a stop bracket that is engaged by use of the hydraulic actuators that control the pitch of the quick attach mounting plate, but this only goes so far in trying to control the bounce introduced in a grading blade assembly where the blade is located well forward of the vehicle, the vehicle arms are still vertically movable, the quick attach mounting introduces undesirable movement, and the hydraulic actuators that control the pitch of the quick attach mounting plate can still bounce against the stop bracket.
In addition, there are times when a fine grading contractor may encounter areas of hard or solid ground, which may include highly compacted soil, frozen portions, concrete or asphalt debris, rocks or other matter. Such areas often require digging and removal by use of heavy duty digging equipment, followed by delivery of new soil to fill as needed because known grading systems are not capable of dealing with such solid ground variations or large chunks of hard dirt that may have been left by a dirt contractor. To date, fine grading systems are not equipped to deal with cutting such hard ground environments. Thus, existing fine grading systems include disadvantages that limit grading performance and that do not enable a fine grading assembly to work through hard ground without extensive intervention from other equipment.
The present disclosure provides a grading system that permits a track vehicle to overcome major shortcomings in the prior art, in two ways. First, the grading system disclosed herein is able to utilize automated control, such as a 2 dimensional or 3 dimensional grading control system, while achieving far better performance including finishing within as little as ⅛″ of the grading site plan. This is accomplished by having significantly less bounce as a result of improved stiffness. There are a few different contributing factors, including a grading blade assembly that extends a much shorter distance from the vehicle, elimination of the quick attach assembly, elimination of the pitch control actuators for the quick attach assembly, and a blade mounting configuration that permits the blade to be moved upward or downward while maintaining a substantially vertical pivot for the blade. The mounting configuration provides for connecting the grading blade assembly to a vehicle that does not include a quick attach assembly or pitch control actuators, while the blade is level and the blade and tracks of the vehicle are on level ground, and while the vertically movable arms of the vehicle are in a first raised position. The first raised position of the vertically movable arms of the vehicle may be, for example, a position that is a few inches, such as 5 inches, above the lower most stop position for the vertically movable arms. With the mounting configuration provided, this enables the grading system to maintain a substantially vertical pivot for the blade, thus keeping the blade level, when the blade is moved upward or downward by controlling only the vertically movable arms of the vehicle. The ability to maintain a substantially vertical pivot also enables the blade to remain level when introducing yaw movements, such as when turning the blade left or right, allowing for consistent machine control.
A second significant improvement over prior art grading systems is that the grading system disclosed may further include a cutting element assembly that is connected to the grading blade assembly. The combined grading blade assembly and cutting element assembly disclosed enable a fine grading system on a track vehicle, such as a skid steer, to avoid and/or consolidate significant steps that otherwise would follow the work of a dirt contractor. Rather than having to use heavy duty equipment to dig out and remove hard ground, debris or other such matter, back fill with new soil, the new grading system disclosed herein utilizes the cutting element assembly to cut and mulch the ground just forward of the blade in a manner sufficient to enable the soil to be fine graded by the very same vehicle. The lift actuator of the cutting element assembly is used to lift a cutting rotor to a raised position when not needed and to lower the rotor to a lowered position that together with the blade can extend below the track of the vehicle, if needed, so as to cut and mulch areas that present such hard ground or debris.
The new grading system presents a relatively mass efficient, compact structure that is mounted to the vertically movable arms at the front of a vehicle. The system facilitates articulation of the grading blade in yaw and roll, without the introduction of pitch movements from a quick attach assembly or the pitch control actuators that typically control the pitch of a quick attach assembly. In fact, the hydraulics for the pitch actuators that would have controlled the tilting of a bucket, for example, can instead be repurposed and connected to the roll actuator for roll control. The vehicle lift actuators for the vertically movable arms may be used to lift or lower the entire grading system, as necessary, while maintaining a substantially vertical pivot for the blade. The efficient, compact structure of the grading system has a relatively short distance between the front of the vehicle and the blade, and can be used with the optional cutting element assembly. Forward support wheels are not needed, permitting greater mobility and use of the new grading system closer to walls or other obstacles. The compact structure optionally also can be utilized in an adjustable system that mounts directly to the vertically moveable arms of the vehicle, or that mounts to a mounting interface that mounts to the vertically movable arms of the vehicle and provides greater vertical adjustment and some pre-selected pitch adjustment. The grading system provides tighter connections and an overall stiffer grading system that reduces the tendency of the blade to bounce or be jostled and stray from its intended path, as is critical for precise machine controlled grading. This enables the grading system to not only be used more effectively with automated control, but with the optional cutting element assembly, the grading system also can cut and mulch or pulverize hard ground and debris. Ultimately, this permits the grading system to more quickly and easily achieve the goal of providing a high quality slab, finishing the fine grading well within the required site plan specifications, while reducing the waste factor.
In a first aspect, the disclosure provides a grading system for connection to a vehicle having vertically movable arms. The grading system includes a grading blade assembly having a frame and a blade. The frame includes a first pivot extending upward between an upper member and a lower member, a second pivot extending forward between the upper member and the lower member, and a rearward facing mounting plate connected to the upper member and to the lower member. The blade includes a forward facing blade body having a lower edge, an upper edge and opposed ends, wherein the blade is connected to the frame via the first pivot and the second pivot. The grading blade assembly also includes a blade yaw actuator connected to the frame and to the blade, wherein the blade yaw actuator adjusts yaw movement of the blade relative to the first pivot, and a blade roll actuator connected to the frame and to the blade, wherein the blade roll actuator adjusts roll movement of the blade relative to the second pivot. The frame of the grading blade assembly is configured to have the first pivot extend substantially vertically and the second pivot extend substantially longitudinally when the grading blade assembly is connected to the vehicle and the blade and vehicle are in a level position on a ground surface and the vertically movable arms of the vehicle are in a first raised position above a lowest most position.
In a second aspect, the grading system of the disclosure optionally has the grading blade assembly include opposed end walls that are connected to and extend forward from the respective opposed ends of the blade, and further includes a cutting element assembly having a rotor including opposed ends, and cutting teeth connected to the rotor and having respective cutting edges at an angle relative to an outer surface of the rotor so as to provide cutting in one rotational direction. The cutting element assembly also includes first and second arms with each arm having a distal end rotatably connected to one of the respective opposed ends of the rotor and a proximal end pivotally connected to one of the respective end walls that extend forward from the opposed ends of the blade. The cutting element assembly further includes at least one lift actuator having a first end pivotally connected to at least one of the arms at a location spaced from the pivotal connection of the arm to the respective end wall and having a second end pivotally connected to the grading blade assembly, wherein the arms of the cutting element assembly have at least one lowered position and at least one raised position, and a drive motor is rotatably coupled to the rotor.
In a third aspect, the disclosure provides a method of connecting a grading system to a vehicle having vertically movable arms including providing a grading system having a grading blade assembly, wherein the grading blade assembly has a frame including a first pivot extending upward between an upper member and a lower member, a second pivot extending forward between the upper member and the lower member, and a rearward facing mounting plate connected to the upper member and to the lower member, with a blade including a forward facing blade body having a lower edge, an upper edge and opposed ends, wherein the blade is connected to the frame via the first pivot and the second pivot. The grading blade assembly further includes a blade yaw actuator connected to the frame and to the blade, wherein the blade yaw actuator adjusts yaw movement of the blade relative to the first pivot, and a blade roll actuator connected to the frame and to the blade, wherein the blade roll actuator adjusts roll movement of the blade relative to the second pivot. The method also includes placing the vehicle and grading blade assembly on level ground, raising the vertically movable arms of the vehicle to a first raised position, connecting the rearward facing mounting plate of the grading blade assembly to the vertically movable arms of the vehicle in the first raised position, wherein the first pivot extends substantially vertically and the second pivot extends substantially longitudinally when the grading blade assembly is connected to the vehicle and the blade and vehicle are in a level position on a ground surface.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and provided for purposes of explanation only, and are not restrictive of the subject matter claimed. Further features and objects of the present disclosure will become more fully apparent in the following description of the preferred embodiments and from the appended claims.
In describing the preferred embodiments, reference is made to the accompanying drawing figures wherein like parts have like reference numerals, and wherein:
It should be understood that the drawings are not to scale. While some mechanical details of the example grading system, including details of fastening means and other plan and section views of the particular components, have not been shown, such details are considered to be within the comprehension of those of ordinary skill in the art in light of the present disclosure. It also should be understood that the present disclosure and claims are not limited to the preferred embodiments illustrated.
Referring generally to
The grading system 10 shown in
The grading blade assembly 20 of the grading system 10 further includes at least one blade yaw actuator 48 connected to the frame 22 and to the blade 34. The blade yaw actuator 48 adjusts yaw movement of the blade 34 relative to the first pivot 24. The grading blade assembly 20 also includes a blade roll actuator 50 connected to the frame 22 and to the blade 34. The blade roll actuator 50 adjusts roll movement of the blade 34 relative to the second pivot 30. The frame 22 of the grading blade assembly 20 is configured to have the first pivot 24 extend substantially vertically and the second pivot 30 extend substantially longitudinally, relative to a longitudinal axis of the vehicle, when the grading blade assembly 20 is connected to the vehicle 12 and the blade 34 and vehicle 12 are in a level position on a ground surface and the vertically movable arms 14 of the vehicle 12 are in a first raised position above a lowest most position. It will be understood that the longitudinal extension of the second pivot 30 is relative to the orientation of the vehicle 12. With the mounting configuration provided, this enables the grading system to maintain a substantially vertical first pivot 24 for the blade 34, thus keeping the blade 34 level, when the blade 34 is moved upward or downward by controlling the vertically movable arms 14 of the vehicle 12. The ability to maintain a substantially vertical first pivot 24 also enables the blade 34 to remain level when introducing yaw movements, such as when turning the blade 34 left to right.
It will be appreciated that the blade yaw actuator 48 and blade roll actuator 50 may be hydraulic actuators. The blade yaw actuator 48 is connected at a first end 48a to the blade 34 at a location spaced laterally from the first pivot 24 toward one of the ends 42, 44 of the blade 34 and connected at a second end 48b to the frame 22 at a location rearward of the first pivot 24. The blade yaw actuator 48 provides for yaw movements or turning of the blade 34, such as may be seen with respect to a partial turn to the right in
In turn, as may be best seen in
The example grading system 10 does not include a pitch actuator, which normally would be connected to a quick attach assembly that may be used to tilt a bucket accessory that would be attached to the quick attach assembly. Without the typical quick attach assembly and pitch actuator associated therewith, the rearward facing mounting plate 32 of the grading system 10 has a pre-selected pitch position that remains substantially the same within the normal range of movement of the vertically movable arms 14 of the vehicle 12 during grading. Also, the frame 22 further includes an upper extension member 54 and a lower extension member 56 that extend forward from the rearward facing mounting plate 32, and that are connected to the upper member 26 and lower member 28 via the first pivot 24.
The grading system 10 preferably includes a mast 60 that is connected to and extends upward from the grading blade assembly 20. The grading system 10 may be used with a laser guided or three dimensional grading control system. Thus, as shown in this example, an electronic component 62 of an automated grade control system, such as a laser receiver or a prism, may be connected to the mast 60. In the present example, a mast receiver 64 is connected to the grading blade assembly 20 and configured to removably receive the mast 60. For example, the mast receiver 64 includes an open tube that is connected to the upper edge 40 of the blade 34, such as be welding or fasteners, and it has an opening 66 to receive the mast 60. If desired, at least one set screw along the side wall of the mast receiver may be used to removably connect the mast 60 to the mast receiver 64, such as by applying a clamping load to the mast 60. Although, it will be appreciated that the mast 60 could be secured to the grading blade assembly 20 by other means of attachment.
The mast 60 also presents a convenient place to mount hydraulic components because it is well above the ground and in an area that is less susceptible to damage. However, because the mast 60 rotates during yaw adjustments relative to a longitudinal axis of the vehicle, hydraulic hoses may tend to be subjected to undesirable flexing events. To combat this in the example shown, as best seen in
The blade 34 of the grading blade assembly 20 may include opposed end walls 80, 82 that are connected to and extend forward from the respective opposed ends 42, 44 of the blade 34. As may be appreciated in
When using the grading system 10, it is possible to operate the one or more blade yaw actuators 48, 52 to impart a yaw adjustment to the blade 34. This may permit an angular adjustment of the blade 34 of up to around 30 degrees, although this may differ as desired. When the blade 34 is positioned at an angle, if it did not include the end walls 80, 82, the material being moved by the blade 34 would tend to be discarded from the rearward raked edge of the blade 34. Accordingly, the end walls 80, 82 of the blade 34 may assist in keeping the graded material in front of the blade, which in turn may assist in filling low spots or otherwise redistributing the graded material. To help control the extent to which the blade 34 is able to capture the graded material, one or both of the end walls 80, 82 may be installed and may include a forward extension 84 and/or downward extension 86.
The grading system 10 is of a particularly efficient compact design that reduces the extent to which the system extends forward of the vehicle 12. This is facilitated, in part, by the frame 22 having a rearward facing mounting plate 32 that is fairly close to the blade 34. The rearward facing mounting plate 32 is connected to the upper member 26 and to the lower member 28. As noted above, these connections may further include upper extension member 54 and lower extension member 56 extending forward from the rearward facing mounting plate 32 and being connected to the upper member 26 and lower member 28 via the first pivot 24. Furthermore, the grading system 10 is connected to the vehicle 12 via the rearward facing mounting plate 32, in conjunction with a mounting assembly. In the first example, a mounting assembly 90 includes a mounting interface 92 that connects to the vehicle 12 and includes a forward facing mounting plate 94.
The mounting interface 92 is constructed with a particular configuration, so as to be able to be mounted to the particular type of vehicle shown. The mounting interface 92 shown in this example is best seen in
The mounting interface 92 may have other structural members that lend further stiffness and/or support to the rearward extending upper and lower brackets 102, 96, and it will be appreciated that alternative configurations and structures may be used to form a suitable mounting interface 92 to provide for secure mounting of the grading system 10 to the vehicle 12. Indeed, the actual configuration likely will differ depending on the particular structure of the vehicle to which the grading system is to be mounted
In addition, the grading system 10 of the first example is height adjustable to a preselected degree relative to the vehicle 12 when resting on a ground surface, as well as by use of the vertically movable arms 14 of the vehicle 12. A pattern of vertically spaced apart holes 32a through the rearward facing mounting plate 32 of the frame 22, and a pattern of vertically spaced apart holes 94a in the forward facing mounting plate 94 of the mounting interface 92 make the frame 22 height adjustable relative to the forward facing mounting plate 94 of the mounting interface 92 that is connected to the front arms 14 of the vehicle 12. For instance, the holes through the respective mounting plates 32, 94 and use of suitable fasteners, such as bolts and nuts, may permit a range of height adjustment from for example 4 inches below the grade to 4 inches above the grade, without repositioning the vertically movable arms 14 of the vehicle 12. It will be appreciated that the range and intervals of adjustment may be constructed as desired and will be limited by the vertical extent of the respective mounting plates and the hole patterns.
In
Relative to prior art grading systems, the more rigid connection and shorter extension of the grading system 10 from the front of the vehicle, while maintaining the blade 34 in a level position throughout its use at varied heights, permit one to more easily achieve the aforementioned goal in fine grading of finishing within ⅜″ or ½″ of the site plan, with as little waste as possible. In fact, by eliminating the shortcomings of the prior art systems, the present grading system 10 is able to achieve substantially better performance and to finish within ⅛″ to ⅜″ of a site plan.
The second example grading system 210 shown in
It will be appreciated that alternative configurations and structures may be used to form a suitable mounting assembly to provide for secure mounting of the grading system 210 directly to a vehicle 12 and the actual configuration likely will differ depending on the particular structure of the vehicle to which the grading system is to be mounted. Also, as with the first example, the mounting assembly 212 of the second example is adjustable with respect to the angle of the rearward facing mounting plate 220, such as by use of shims when connecting the rearward extending upper brackets 218 to the front arms of a vehicle, which may, for example, be in the same way as was shown for the first example, or the connection may be made in an alternative suitable manner.
Given the disclosure herein, it will be understood that the grading system 10 of the first example, and the grading system 210 of the second example, also may include an optional cutting element assembly 110. The cutting element assembly 110 is ideally suited for use with the grading blade assembly 20, but it will be understood that the cutting element assembly 110 alternatively could be used on other grading blade assemblies to overcome the aforementioned issues relating to hard or solid ground and debris.
The cutting element assembly 110 of the grading system 10 includes a rotor 112 having opposed ends 112a, 112b, and cutting teeth 118 connected to the rotor 112. The cutting teeth 118 preferably have respective cutting edges 120 at an angle relative to an outer surface 122 of the rotor 112, so as to provide cutting in one rotational direction. The cutting element assembly 110 additionally has first and second arms 124, 126, respectively, with each having a distal end 124a, 126a, respectively, rotatably connected to one of the respective opposed ends 112a, 112b of the rotor 112, and a proximal end 124b, 126b, respectively, pivotally connected to one of the respective end walls 80, 82 that extends forward from the opposed ends 42, 44 of the blade 34. At least one lift actuator 130 has a first end 130a pivotally connected to at least one of the first and second arms 124, 126 at a location spaced from the pivotal connection of the arm 124, 126 to the respective end wall 80, 82, and having a second end 130b pivotally connected to the grading blade assembly 20. In this example, one lift actuator 130 is connected to the arm 124 and to the end wall 80. The at least one lift actuator 130 enables the arms 124, 126 of the cutting element assembly 110 to have at least one lowered position and at least one raised position. In the example shown, the at least one lowered position may, for example, be identified as when the arms 124, 126 lower the rotor 112 to engage the ground surface, and at least one raised position may, for example, be identified as when the arms 124, 126 raise the rotor 112 and are pivoted to the furthest extent rearward, so as not to require lifting force from the lift actuator 130. It will be appreciated that the arms 124, 126 may have numerous raised positions within the pivotal range from a lowermost position that may extend below the ground surface, depending on the height of the grading blade assembly 20, to the extreme highest position noted as when the rotor 112 is pivoted to the furthest extent rearward. The cutting element assembly 110 also includes a drive motor 132 rotatably coupled to the rotor 112.
The example grading system 10 is shown with a stabilizing member 134 extending between and fixedly connected to the respective arms 124, 126. It will be appreciated that the stabilizing member 134 may be of tubular or solid construction, but is intended to provide additional structure to assist in keeping the arms 124 and 126 in registration with each other, so as to stay parallel with respect to the distance between the points along the arms, as well as with respect to their pivotal position. One other aspect of the present example that is used to keep the arms 124, 126 in registration with each other is that the pivotal connection of the proximal ends 124b, 126b of the arms 124, 126 to the respective end walls 80, 82 includes a drive shaft 136 fixedly connected to the proximal ends 124b, 126b of the arms 124, 126 and rotatably connected to the end walls 80, 82, respectively. As with the stabilizing member 134 it will be appreciated that the drive shaft 136 may be of tubular or solid construction. The drive shaft 136 being fixedly connected to the proximal ends 124b, 126b of the arms 124, 126 ensures that an input for rotational movement by the lift actuator 130 to the arm 124 will be transmitted to and cause a similar rotational movement of the other arm 126. As an alternative to use of the drive shaft 136, each arm 124, 126 could be separately connected to a lift actuator for independent but coordinated simultaneous movement.
The cutting teeth 118 may be fixedly connected to the rotor 112 by welding, or by use of individual holding devices for removable mounting of the teeth. Such individual holding devices also may be adjustable, to compensate with wear of the teeth over time. It is preferable that the cutting teeth 118 be very durable, so as to avoid constant replacement or adjustment, and as such, the cutting teeth 118 may be constructed of foundation welding bar cutting teeth. Thus, it is preferable that the cutting teeth 118 may be suitable for use on a cold planar to strip asphalt or concrete pavement, because this would provide for more aggressive cutting and greater durability. However, it will be appreciated that alternative teeth constructions may be used. It also will be appreciated that the rotor 112 may be driven in only one rotational direction, but alternatively could be configured to rotate in both forward and rearward directions. The particular cutting teeth 118 shown in the first example would provide for more aggressive cutting in one direction, and if configured to rotate in the opposite direction, would provide more of a raking effect.
The cutting teeth 118 also preferably are connected to the rotor 112 in a non-linear pattern. This may be seen in the example grading system 10 where the cutting teeth 118 may be said to be in a curve linear pattern across the outer surface 122 of the rotor 112. This configuration provides a further advantage of the example cutting element assembly 110 because it helps to reduce the torque required to rotate the rotor 112 when cutting into the hard ground surface by permitting only a few cutting teeth 118 to be in the same ground engaging position relative to each other across the length of the rotor 112. This is beneficial relative to cutting teeth being placed in linear rows arranged to extend longitudinally along the rotor 112. The non-linear pattern helps to maintain a more consistent number of teeth in engagement with the ground, and therefore, a more consistent level of torque required during cutting and mulching of the varied material encountered.
While the rotor 112 is driven by the drive motor 132, it will be appreciated that there are alternative ways of achieving this. For instance, as best seen in
As noted previously, it may be desirable to have the rotor 112 driven by the drive motor 132 in one rotational direction. If this is desired and a hydraulic motor is used as the drive motor 132, then the connection of the drive motor 132 to a hydraulic circuit optionally may include a one-way bypass valve 146 between a fluid input 148 and a fluid outlet 150, as best seen in
It will be appreciated that, as described above, the grading system 10 may include a mast 60 that is connected to and extends upward from the grading blade assembly 20, and may include an electronic component 62 of an automated grade control system connected to the mast 60. The grading system 10 permits positions of the grading blade assembly 20 and positions of the cutting element assembly 110 each to be subject to an automated grade control system.
To control the potential depth of the cutting achieved with the cutting element assembly 110 in a fully lowered position, the end walls 80, 82 of the grading blade assembly 20 may include pivot limiters 152 for the arms 124, 126. Thus, the use of pivot limiters 152 can be very beneficial in that the lift actuator 130 may move the arms 124, 126 to a lowered position and does not have to apply a continuous lifting force, but rather can set the arms 124, 126 on the pivot limiters 152. While the weight of the cutting element assembly 110 may be sufficient to keep the arms 124, 126 engaged with the respective pivot limiters 152, to the extent necessary, the lift actuator 130 may apply a downward force to hold the arms 124, 126 against the pivot limiters 152. In addition, in order to account for the wear of the cutting teeth 118 or to make a fine adjustment in positioning, it is preferable that the pivot limiters 152 include adjustable stackable stops 154. As shown partially exploded in
From the above disclosure, it will be apparent that a grading system constructed in accordance with this disclosure may include a number of structural aspects that provide advantages over prior art grading systems for use on vehicles, depending upon the specific design chosen.
It will be appreciated that a grading system may have a grading blade assembly, a cutting element assembly, or both a grading blade assembly and a cutting element assembly consistent with this disclosure, and each assembly may be embodied in various configurations. Any variety of suitable materials of construction, configurations, shapes and sizes for the components and methods of connecting the components may be utilized to meet the particular needs and requirements of an end user. It will be apparent to those skilled in the art that various modifications can be made in the design and construction of such a grading system without departing from the scope or spirit of the claimed subject matter, and that the claims are not limited to the preferred embodiment illustrated herein.
Filing Document | Filing Date | Country | Kind |
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PCT/US2018/023515 | 3/21/2018 | WO | 00 |